/**
 * CUETools.Flake: pure managed FLAC audio encoder
 * Copyright (c) 2009 Grigory Chudov
 * Based on Flake encoder, http://flake-enc.sourceforge.net/
 * Copyright (c) 2006-2009 Justin Ruggles
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#define NOINTEROP

using System;
using System.ComponentModel;
using System.Text;
using System.IO;
using System.Collections.Generic;
using System.Security.Cryptography;
#if INTEROP
using System.Runtime.InteropServices;
#endif
using CUETools.Codecs;

namespace CUETools.Codecs.FLAKE
{
    public class FlakeWriterSettings : AudioEncoderSettings
    {
        public FlakeWriterSettings()
            : base()
        {
        }

        public override string GetSupportedModes(out string defaultMode)
        {
            defaultMode = "7";
            return this.AllowNonSubset || (this.PCM != null && this.PCM.SampleRate > 48000) ? "0 1 2 3 4 5 6 7 8 9 10 11" : "0 1 2 3 4 5 6 7 8";
        }

        public bool IsSubset()
        {
            return (BlockSize == 0 || (BlockSize <= 16384 && (PCM.SampleRate > 48000 || BlockSize <= 4608)))
                && (PCM.SampleRate > 48000 || MaxLPCOrder <= 12)
                && MaxPartitionOrder <= 8
                ;
            //The blocksize bits in the frame header must be 0001-1110. The blocksize must be <=16384; if the sample rate is <= 48000Hz, the blocksize must be <=4608.
            //The sample rate bits in the frame header must be 0001-1110.
            //The bits-per-sample bits in the frame header must be 001-111.
            //If the sample rate is <= 48000Hz, the filter order in LPC subframes must be less than or equal to 12, i.e. the subframe type bits in the subframe header may not be 101100-111111.
            //The Rice partition order in a Rice-coded residual section must be less than or equal to 8.
        }

        public void Validate()
        {
            if (EncoderModeIndex < 0)
                throw new Exception("unsupported encoder mode");
            var thisModeSettings = FlakeWriterSettings.modeSettings[EncoderModeIndex];
            if (MaxLPCOrder < 0)
                MaxLPCOrder = thisModeSettings.MaxLPCOrder;
            if (MinFixedOrder < 0)
                MinFixedOrder = thisModeSettings.MinFixedOrder;
            if (MaxFixedOrder < 0)
                MaxFixedOrder = thisModeSettings.MaxFixedOrder;
            if (MaxPartitionOrder < 0)
                MaxPartitionOrder = thisModeSettings.MaxPartitionOrder;
            if (Padding < 0)
                throw new Exception("unsupported padding value " + Padding.ToString());
            if (BlockSize != 0 && (BlockSize < 256 || BlockSize >= Flake.MAX_BLOCKSIZE))
                throw new Exception("unsupported block size " + BlockSize.ToString());
            if (MinLPCOrder > MaxLPCOrder || MaxLPCOrder > lpc.MAX_LPC_ORDER)
                throw new Exception("invalid MaxLPCOrder " + MaxLPCOrder.ToString());
            if (MinFixedOrder < 0 || MinFixedOrder > 4)
                throw new Exception("invalid MinFixedOrder " + MinFixedOrder.ToString());
            if (MaxFixedOrder < 0 || MaxFixedOrder > 4)
                throw new Exception("invalid MaxFixedOrder " + MaxFixedOrder.ToString());
            if (MinPartitionOrder < 0)
                throw new Exception("invalid MinPartitionOrder " + MinPartitionOrder.ToString());
            if (MinPartitionOrder > MaxPartitionOrder || MaxPartitionOrder > 8)
                throw new Exception("invalid MaxPartitionOrder " + MaxPartitionOrder.ToString());
            if (!AllowNonSubset && !IsSubset())
                throw new Exception("the encoding parameters specified do not conform to the FLAC Subset");
        }

        private static FlakeWriterSettings[] modeSettings =
        {
            new FlakeWriterSettings() {
                MinFixedOrder = 3, MaxFixedOrder = 2, MaxLPCOrder = 6, MaxPartitionOrder = 6,
            },
            new FlakeWriterSettings() {
                MinFixedOrder = 2, MaxFixedOrder = 2, MaxLPCOrder = 8, MaxPartitionOrder = 6,
            },
            new FlakeWriterSettings() {
                MinFixedOrder = 2, MaxFixedOrder = 2, MaxLPCOrder = 12, MaxPartitionOrder = 6,
            },
            new FlakeWriterSettings() {
                MinFixedOrder = 2, MaxFixedOrder = 2, MaxLPCOrder = 8, MaxPartitionOrder = 8,
            },
            new FlakeWriterSettings() {
                MinFixedOrder = 2, MaxFixedOrder = 2, MaxLPCOrder = 12, MaxPartitionOrder = 8,
            },
            new FlakeWriterSettings() {
                MinFixedOrder = 2, MaxFixedOrder = 2, MaxLPCOrder = 12, MaxPartitionOrder = 8,
            },
            new FlakeWriterSettings() {
                MinFixedOrder = 2, MaxFixedOrder = 2, MaxLPCOrder = 12, MaxPartitionOrder = 8,
            },
            new FlakeWriterSettings() {
                MinFixedOrder = 2, MaxFixedOrder = 2, MaxLPCOrder = 12, MaxPartitionOrder = 8,
            },
            new FlakeWriterSettings() {
                MinFixedOrder = 0, MaxFixedOrder = 2, MaxLPCOrder = 12, MaxPartitionOrder = 8,
            },
            new FlakeWriterSettings() {
                MinFixedOrder = 2, MaxFixedOrder = 2, MaxLPCOrder = 32, MaxPartitionOrder = 8,
            },
            new FlakeWriterSettings() {
                MinFixedOrder = 0, MaxFixedOrder = 4, MaxLPCOrder = 32, MaxPartitionOrder = 8,
            },
            new FlakeWriterSettings() {
                MinFixedOrder = 0, MaxFixedOrder = 4, MaxLPCOrder = 32, MaxPartitionOrder = 8,
            },
        };

        [DefaultValue(-1)]
        [Browsable(false)]
        [DisplayName("MinFixedOrder")]
        [SRDescription(typeof(Properties.Resources), "MinFixedOrderDescription")]
        public int MinFixedOrder { get; set; }

        [DefaultValue(-1)]
        [Browsable(false)]
        [DisplayName("MaxFixedOrder")]
        [SRDescription(typeof(Properties.Resources), "MaxFixedOrderDescription")]
        public int MaxFixedOrder { get; set; }

        [DefaultValue(1)]
        [Browsable(false)]
        [DisplayName("MinLPCOrder")]
        [SRDescription(typeof(Properties.Resources), "MinLPCOrderDescription")]
        public int MinLPCOrder { get; set; }

        [DefaultValue(-1)]
        [Browsable(false)]
        [DisplayName("MaxLPCOrder")]
        [SRDescription(typeof(Properties.Resources), "MaxLPCOrderDescription")]
        public int MaxLPCOrder { get; set; }

        [DefaultValue(0)]
        [DisplayName("MinPartitionOrder")]
        [Browsable(false)]
        [SRDescription(typeof(Properties.Resources), "MinPartitionOrderDescription")]
        public int MinPartitionOrder { get; set; }

        [DefaultValue(-1)]
        [DisplayName("MaxPartitionOrder")]
        [Browsable(false)]
        [SRDescription(typeof(Properties.Resources), "MaxPartitionOrderDescription")]
        public int MaxPartitionOrder { get; set; }

        [DefaultValue(false)]
        [DisplayName("Verify")]
        [SRDescription(typeof(Properties.Resources), "DoVerifyDescription")]
        public bool DoVerify { get; set; }

        [DefaultValue(true)]
        [DisplayName("MD5")]
        [SRDescription(typeof(Properties.Resources), "DoMD5Description")]
        public bool DoMD5 { get; set; }

        [DefaultValue(false)]
        [DisplayName("Allow Non-subset")]
        [SRDescription(typeof(Properties.Resources), "AllowNonSubsetDescription")]
        public bool AllowNonSubset { get; set; }
    }

	[AudioEncoderClass("cuetools", "flac", true, 4, typeof(FlakeWriterSettings))]
	//[AudioEncoderClass("libFlake nonsub", "flac", true, "9 10 11", "9", 3, typeof(FlakeWriterSettings))]
	public class FlakeWriter : IAudioDest
	{
		Stream _IO = null;
		string _path;
		long _position;

		// number of audio channels
		// set by user prior to calling flake_encode_init
		// valid values are 1 to 8
		int channels, ch_code;

		// audio sample rate in Hz
		// set by user prior to calling flake_encode_init
		int sr_code0, sr_code1;

		// sample size in bits
		// set by user prior to calling flake_encode_init
		// only 16-bit is currently supported
		int bps_code;

		// total stream samples
		// set by user prior to calling flake_encode_init
		// if 0, stream length is unknown
		int sample_count = -1;

		FlakeEncodeParams eparams;

		// maximum frame size in bytes
		// set by flake_encode_init
		// this can be used to allocate memory for output
		int max_frame_size;

		byte[] frame_buffer = null;

		int frame_count = 0;

		long first_frame_offset = 0;

#if INTEROP
		TimeSpan _userProcessorTime;
#endif

		// header bytes
		// allocated by flake_encode_init and freed by flake_encode_close
		byte[] header;

		int[] samplesBuffer;
		int[] verifyBuffer;
		int[] residualBuffer;
		float[] windowBuffer;
		double[] windowScale;
		int samplesInBuffer = 0;

		int m_blockSize = 0;
		int _totalSize = 0;
		int _windowsize = 0, _windowcount = 0;

		Crc8 crc8;
		MD5 md5;

		FlacFrame frame;
		FlakeReader verify;

		SeekPoint[] seek_table;
		int seek_table_offset = -1;

		bool inited = false;

		public FlakeWriter(string path, Stream IO, FlakeWriterSettings settings)
		{
            m_settings = settings.Clone() as FlakeWriterSettings;
            m_settings.Validate();

			//if (Settings.PCM.BitsPerSample != 16)
			//    throw new Exception("Bits per sample must be 16.");
            //if (Settings.PCM.ChannelCount != 2)
            //    throw new Exception("ChannelCount must be 2.");

            channels = Settings.PCM.ChannelCount;

			// flake_validate_params

			_path = path;
			_IO = IO;

			samplesBuffer = new int[Flake.MAX_BLOCKSIZE * (channels == 2 ? 4 : channels)];
			residualBuffer = new int[Flake.MAX_BLOCKSIZE * (channels == 2 ? 10 : channels + 1)];
			windowBuffer = new float[Flake.MAX_BLOCKSIZE * 2 * lpc.MAX_LPC_WINDOWS];
			windowScale = new double[lpc.MAX_LPC_WINDOWS];

            eparams.flake_set_defaults(m_settings);

			crc8 = new Crc8();
			frame = new FlacFrame(channels * 2);
		}

        public FlakeWriter(string path, FlakeWriterSettings settings)
            : this(path, null, settings)
		{
		}

		public int TotalSize
		{
			get
			{
				return _totalSize;
			}
		}

		FlakeWriterSettings m_settings;

        public AudioEncoderSettings Settings
		{
			get
			{
				return m_settings;
			}
		}

#if INTEROP
		[DllImport("kernel32.dll")]
		static extern bool GetThreadTimes(IntPtr hThread, out long lpCreationTime, out long lpExitTime, out long lpKernelTime, out long lpUserTime);
		[DllImport("kernel32.dll")]
		static extern IntPtr GetCurrentThread();
#endif

		void DoClose()
		{
			if (inited)
			{
				while (samplesInBuffer > 0)
				{
                    m_blockSize = samplesInBuffer;
					output_frame();
				}

				if (_IO.CanSeek)
				{
					if (sample_count <= 0 && _position != 0)
					{
						BitWriter bitwriter = new BitWriter(header, 0, 4);
						bitwriter.writebits(32, (int)_position);
						bitwriter.flush();
						_IO.Position = 22;
						_IO.Write(header, 0, 4);
					}

					if (md5 != null)
					{
						md5.TransformFinalBlock(frame_buffer, 0, 0);
						_IO.Position = 26;
						_IO.Write(md5.Hash, 0, md5.Hash.Length);
					}

					if (seek_table != null)
					{
						_IO.Position = seek_table_offset;
						int len = write_seekpoints(header, 0, 0);
						_IO.Write(header, 4, len - 4);
					}
				}
				_IO.Close();
				inited = false;
            }

#if INTEROP
			long fake, KernelStart, UserStart;
			GetThreadTimes(GetCurrentThread(), out fake, out fake, out KernelStart, out UserStart);
			_userProcessorTime = new TimeSpan(UserStart);
#endif
		}

		public void Close()
		{
			DoClose();
			if (sample_count > 0 && _position != sample_count)
				throw new Exception(Properties.Resources.ExceptionSampleCount);
		}

		public void Delete()
		{
			if (inited)
			{
				_IO.Close();
				inited = false;
			}

			if (_path != "")
				File.Delete(_path);
		}

		public long Position
		{
			get
			{
				return _position;
			}
		}

		public long FinalSampleCount
		{
			set { sample_count = (int)value; }
		}

		public OrderMethod OrderMethod
		{
			get { return eparams.order_method; }
			set { eparams.order_method = value; }
		}

		public PredictionType PredictionType
		{
			get { return eparams.prediction_type; }
			set { eparams.prediction_type = value; }
		}

		public StereoMethod StereoMethod
		{
			get { return eparams.stereo_method; }
			set { eparams.stereo_method = value; }
		}

		public WindowMethod WindowMethod
		{
			get { return eparams.window_method; }
			set { eparams.window_method = value; }
		}

        public int DevelopmentMode
        {
            get { return eparams.development_mode; }
            set { eparams.development_mode = value; }
        }

        public int MinPrecisionSearch
		{
			get { return eparams.lpc_min_precision_search; }
			set
			{
				if (value < 0 || value > eparams.lpc_max_precision_search)
					throw new Exception("unsupported MinPrecisionSearch value");
				eparams.lpc_min_precision_search = value;
			}
		}

		public int MaxPrecisionSearch
		{
			get { return eparams.lpc_max_precision_search; }
			set
			{
				if (value < eparams.lpc_min_precision_search || value >= lpc.MAX_LPC_PRECISIONS)
					throw new Exception("unsupported MaxPrecisionSearch value");
				eparams.lpc_max_precision_search = value;
			}
		}

		public WindowFunction WindowFunction
		{
			get { return eparams.window_function; }
			set { eparams.window_function = value; }
		}

		public bool DoSeekTable
		{
			get { return eparams.do_seektable; }
			set { eparams.do_seektable = value; }
		}

		public int VBRMode
		{
			get { return eparams.variable_block_size; }
			set { eparams.variable_block_size = value; }
		}

		public int EstimationDepth
		{
			get
			{
				return eparams.estimation_depth;
			}
			set
			{
				if (value > 32 || value < 1)
					throw new Exception("invalid estimation_depth " + value.ToString());
				eparams.estimation_depth = value;
			}
		}

		public TimeSpan UserProcessorTime
		{
			get 
			{
#if INTEROP 
				return _userProcessorTime; 
#else
				return new TimeSpan(0);
#endif
			}
		}

		unsafe int get_wasted_bits(int* signal, int samples)
		{
			int i, shift;
			int x = 0;

			for (i = 0; i < samples && 0 == (x & 1); i++)
				x |= signal[i];

			if (x == 0)
			{
				shift = 0;
			}
			else
			{
				for (shift = 0; 0 == (x & 1); shift++)
					x >>= 1;
			}

			if (shift > 0)
			{
				for (i = 0; i < samples; i++)
					signal[i] >>= shift;
			}

			return shift;
		}

		/// <summary>
		/// Copy channel-interleaved input samples into separate subframes
		/// </summary>
		/// <param name="samples"></param>
		/// <param name="pos"></param>
		/// <param name="block"></param>
 		unsafe void copy_samples(int[,] samples, int pos, int block)
		{
			fixed (int* fsamples = samplesBuffer, src = &samples[pos, 0])
			{
				if (channels == 2)
				{
					if (eparams.stereo_method == StereoMethod.Independent)
						AudioSamples.Deinterlace(fsamples + samplesInBuffer, fsamples + Flake.MAX_BLOCKSIZE + samplesInBuffer, src, block);
					else
					{
						int* left = fsamples + samplesInBuffer;
						int* right = left + Flake.MAX_BLOCKSIZE;
						int* leftM = right + Flake.MAX_BLOCKSIZE;
						int* rightM = leftM + Flake.MAX_BLOCKSIZE;
						for (int i = 0; i < block; i++)
						{
							int l = src[2 * i];
							int r = src[2 * i + 1];
							left[i] = l;
							right[i] = r;
							leftM[i] = (l + r) >> 1;
							rightM[i] = l - r;
						}
					}
				}
				else
					for (int ch = 0; ch < channels; ch++)
					{
						int* psamples = fsamples + ch * Flake.MAX_BLOCKSIZE + samplesInBuffer;
						for (int i = 0; i < block; i++)
							psamples[i] = src[i * channels + ch];
					}
			}
			samplesInBuffer += block;
		}

		//unsafe static void channel_decorrelation(int* leftS, int* rightS, int *leftM, int *rightM, int blocksize)
		//{
		//    for (int i = 0; i < blocksize; i++)
		//    {
		//        leftM[i] = (leftS[i] + rightS[i]) >> 1;
		//        rightM[i] = leftS[i] - rightS[i];
		//    }
		//}

		unsafe void encode_residual_verbatim(int* res, int* smp, uint n)
		{
			AudioSamples.MemCpy(res, smp, (int) n);
		}

		unsafe static void encode_residual_fixed(int* res, int* smp, int n, int order)
		{
			int i;
			int s0, s1, s2;
			switch (order)
			{
				case 0:
					AudioSamples.MemCpy(res, smp, n);
					return;
				case 1:
					*(res++) = s1 = *(smp++);
					for (i = n - 1; i > 0; i--)
					{
						s0 = *(smp++);
						*(res++) = s0 - s1;
						s1 = s0;
					}
					return;
				case 2:
					*(res++) = s2 = *(smp++);
					*(res++) = s1 = *(smp++);
					for (i = n - 2; i > 0; i--)
					{
						s0 = *(smp++);
						*(res++) = s0 - 2 * s1 + s2;
						s2 = s1;
						s1 = s0;
					}
					return;
				case 3:
					res[0] = smp[0];
					res[1] = smp[1];
					res[2] = smp[2];
					for (i = 3; i < n; i++)
					{
						res[i] = smp[i] - 3 * smp[i - 1] + 3 * smp[i - 2] - smp[i - 3];
					}
					return;
				case 4:
					res[0] = smp[0];
					res[1] = smp[1];
					res[2] = smp[2];
					res[3] = smp[3];
					for (i = 4; i < n; i++)
					{
						res[i] = smp[i] - 4 * smp[i - 1] + 6 * smp[i - 2] - 4 * smp[i - 3] + smp[i - 4];
					}
					return;
				default:
					return;
			}
		}

		static unsafe uint calc_optimal_rice_params(int porder, int* parm, ulong* sums, uint n, uint pred_order, ref int method)
		{
			uint part = (1U << porder);
			uint cnt = (n >> porder) - pred_order;
			int maxK = method > 0 ? 30 : Flake.MAX_RICE_PARAM;
			int k = cnt > 0 ? Math.Min(maxK, BitReader.log2i(sums[0] / cnt)) : 0;
			int realMaxK0 = k;
			ulong all_bits = cnt * ((uint)k + 1U) + (sums[0] >> k);
			parm[0] = k;
			cnt = (n >> porder);
			for (uint i = 1; i < part; i++)
			{
				k = Math.Min(maxK, BitReader.log2i(sums[i] / cnt));
				realMaxK0 = Math.Max(realMaxK0, k);
				all_bits += cnt * ((uint)k + 1U) + (sums[i] >> k);
				parm[i] = k;
			}
			method = realMaxK0 > Flake.MAX_RICE_PARAM ? 1 : 0;
			return (uint)all_bits + ((4U + (uint)method) * part);
		}

		static unsafe void calc_lower_sums(int pmin, int pmax, ulong* sums)
		{
			for (int i = pmax - 1; i >= pmin; i--)
			{
				for (int j = 0; j < (1 << i); j++)
				{
					sums[i * Flake.MAX_PARTITIONS + j] =
						sums[(i + 1) * Flake.MAX_PARTITIONS + 2 * j] +
						sums[(i + 1) * Flake.MAX_PARTITIONS + 2 * j + 1];
				}
			}
		}

		static unsafe void calc_sums(int pmin, int pmax, uint* data, uint n, uint pred_order, ulong* sums)
		{
			int parts = (1 << pmax);
			uint* res = data + pred_order;
			uint cnt = (n >> pmax) - pred_order;
			ulong sum = 0;
			for (uint j = cnt; j > 0; j--)
				sum += *(res++);
			sums[0] = sum;
			cnt = (n >> pmax);
			for (int i = 1; i < parts; i++)
			{
				sum = 0;
				for (uint j = cnt; j > 0; j--)
					sum += *(res++);
				sums[i] = sum;
			}
		}

		/// <summary>
		/// Special case when (n >> pmax) == 18
		/// </summary>
		/// <param name="pmin"></param>
		/// <param name="pmax"></param>
		/// <param name="data"></param>
		/// <param name="n"></param>
		/// <param name="pred_order"></param>
		/// <param name="sums"></param>
		static unsafe void calc_sums18(int pmin, int pmax, uint* data, uint n, uint pred_order, ulong* sums)
		{
			int parts = (1 << pmax);
			uint* res = data + pred_order;
			uint cnt = 18 - pred_order;
			ulong sum = 0;
			for (uint j = cnt; j > 0; j--)
				sum += *(res++);
			sums[0] = sum;
			for (int i = 1; i < parts; i++)
			{
				sums[i] = 0UL +
					*(res++) + *(res++) + *(res++) + *(res++) +
					*(res++) + *(res++) + *(res++) + *(res++) +
					*(res++) + *(res++) + *(res++) + *(res++) +
					*(res++) + *(res++) + *(res++) + *(res++) +
					*(res++) + *(res++);
			}
		}

		/// <summary>
		/// Special case when (n >> pmax) == 18
		/// </summary>
		/// <param name="pmin"></param>
		/// <param name="pmax"></param>
		/// <param name="data"></param>
		/// <param name="n"></param>
		/// <param name="pred_order"></param>
		/// <param name="sums"></param>
		static unsafe void calc_sums16(int pmin, int pmax, uint* data, uint n, uint pred_order, ulong* sums)
		{
			int parts = (1 << pmax);
			uint* res = data + pred_order;
			uint cnt = 16 - pred_order;
			ulong sum = 0;
			for (uint j = cnt; j > 0; j--)
				sum += *(res++);
			sums[0] = sum;
			for (int i = 1; i < parts; i++)
			{
				sums[i] = 0UL +
					*(res++) + *(res++) + *(res++) + *(res++) +
					*(res++) + *(res++) + *(res++) + *(res++) +
					*(res++) + *(res++) + *(res++) + *(res++) +
					*(res++) + *(res++) + *(res++) + *(res++);
			}
		}

        static unsafe uint calc_rice_params_sums(RiceContext rc, int pmin, int pmax, ulong* sums, uint n, uint pred_order, int bps)
        {
            int* parm = stackalloc int[(pmax + 1) * Flake.MAX_PARTITIONS];
            //uint* bits = stackalloc uint[Flake.MAX_PARTITION_ORDER];

            //assert(pmin >= 0 && pmin <= Flake.MAX_PARTITION_ORDER);
            //assert(pmax >= 0 && pmax <= Flake.MAX_PARTITION_ORDER);
            //assert(pmin <= pmax);

            // sums for lower levels
            calc_lower_sums(pmin, pmax, sums);

            uint opt_bits = AudioSamples.UINT32_MAX;
            int opt_porder = pmin;
            int opt_method = 0;
            for (int i = pmin; i <= pmax; i++)
            {
                int method = bps > 16 ? 1 : 0;
                uint bits = calc_optimal_rice_params(i, parm + i * Flake.MAX_PARTITIONS, sums + i * Flake.MAX_PARTITIONS, n, pred_order, ref method);
                if (bits <= opt_bits)
                {
                    opt_bits = bits;
                    opt_porder = i;
                    opt_method = method;
                }
            }

            rc.porder = opt_porder;
            rc.coding_method = opt_method;
            fixed (int* rparms = rc.rparams)
                AudioSamples.MemCpy(rparms, parm + opt_porder * Flake.MAX_PARTITIONS, (1 << opt_porder));

            return opt_bits;
        }

		static unsafe uint calc_rice_params(RiceContext rc, int pmin, int pmax, int* data, uint n, uint pred_order, int bps)
		{
			uint* udata = stackalloc uint[(int)n];
			ulong* sums = stackalloc ulong[(pmax + 1) * Flake.MAX_PARTITIONS];

			//assert(pmin >= 0 && pmin <= Flake.MAX_PARTITION_ORDER);
			//assert(pmax >= 0 && pmax <= Flake.MAX_PARTITION_ORDER);
			//assert(pmin <= pmax);

			for (uint i = 0; i < n; i++)
				udata[i] = (uint) ((data[i] << 1) ^ (data[i] >> 31));

			// sums for highest level
			if ((n >> pmax) == 18)
				calc_sums18(pmin, pmax, udata, n, pred_order, sums + pmax * Flake.MAX_PARTITIONS);
			else if ((n >> pmax) == 16)
				calc_sums16(pmin, pmax, udata, n, pred_order, sums + pmax * Flake.MAX_PARTITIONS);
			else
				calc_sums(pmin, pmax, udata, n, pred_order, sums + pmax * Flake.MAX_PARTITIONS);

            return calc_rice_params_sums(rc, pmin, pmax, sums, n, pred_order, bps);
		}

		static int get_max_p_order(int max_porder, int n, int order)
		{
			int porder = Math.Min(max_porder, BitReader.log2i(n ^ (n - 1)));
			if (order > 0)
				porder = Math.Min(porder, BitReader.log2i(n / order));
			return porder;
		}

//        private static int[,] best_x = new int[14,8193];
        private static int[][] good_x = new int[][] {
new int[] {}, // 0
new int[] { // 1
0x03,0x01,0x00,0x02
}, 
new int[] {// 2
0x01,0x07,0x06,0x02, 0x03,0x04,0x00,0x05
},
new int[] { // 3
0x0b,0x0f,0x0e,0x0d, 0x03,0x01,0x05,0x02
}, 
new int[] { //4
0x17,0x09,0x03,0x0a, 0x06,0x1d,0x1f,0x05, 0x1c,0x0d,0x07,0x0c,
},
new int[] { // 5
0x2b,0x3d,0x37,0x07, 0x11,0x15,0x36,0x3f,
}, 
new int[] { // 6
0x6b,0x15,0x7e,0x31, 0x07,0x1a,0x29,0x26, 0x5d,0x23,0x6f,0x19, 0x56,0x75
},
new int[] { // 7
0xdb,0xef,0xb5,0x47, 0xee,0x63,0x0b,0xfd, 0x31,0xbe,0xed,0x33, 0xff,0xfb,0xd6,0xbb
},
new int[] { // 8
0x1bb,0x1c7,0x069,0x087, 0x1fd,0x16e,0x095,0x1de, 0x066,0x071,0x055,0x09a,
},
new int[] { // 9
0x36b,0x3bd,0x097,0x0c3, 0x0e3,0x0b1,0x107,0x2de, 0x3ef,0x2fb,0x3d5,0x139
},
new int[] { // 10
//0x0e3,0x199,0x383,0x307, 0x1e3,0x01f,0x269,0x0f1, 0x266,0x03f,0x2cd,0x1c3, 0x19a,0x387,0x339,0x259,
0x6eb,0x187,0x77d,0x271, 0x195,0x259,0x5ae,0x169,
},
new int[] { // 11
0xddb,0xf77,0xb6d,0x587, 0x2c3,0x03b,0xef5,0x1e3, 0xdbe,
},
new int[] { // 12
0x1aeb,0x0587,0x0a71,0x1dbd, 0x0559,0x0aa5,0x0a2e,0x0d43, 0x05aa,0x00f3,0x0696,0x03c6,
},
new int[] { // 13
0x35d7,0x2f6f,0x0aa3,0x1569, 0x150f,0x3d79,0x0dc3,0x309f/*?*/,
},
new int[] { // 14
0x75d7,0x5f7b,0x6a8f,0x29a3,
},
new int[] { // 15
0xddd7,0xaaaf,0x55c3,0xf77b,
},
new int[] { // 16
0x1baeb,0x1efaf,0x1d5bf,0x1cff3,
},
new int[] { // 17
0x36dd7,0x3bb7b,0x3df6f,0x2d547,
},
new int[] { // 18
0x75dd7,0x6f77b,0x7aaaf,0x5ddd3,
},
new int[] { // 19
0xdddd7,0xf777b,0xd5547,0xb6ddb,
},
new int[] { // 20
0x1baeeb,0x1efbaf,0x1aaabf,0x17bbeb,
},
new int[] { // 21
0x376dd7,0x3ddf7b,0x2d550f,0x0aaaa3,
},
new int[] { // 22
0x6eddd7,0x77777b,0x5dcd4f,0x5d76f9,
},
new int[] { // 23
0xdeddd7,0xb5b6eb,0x55552b,0x2aaac3,
},
new int[] { // 24
0x1dddbb7,0x1b76eeb,0x17bbf5f,0x1eeaa9f,
},
new int[] { // 25
},
new int[] { // 26
},
new int[] { // 27
},
new int[] { // 28
},
new int[] { // 29
},
new int[] { // 30
},
        };

        unsafe void postprocess_coefs(FlacFrame frame, FlacSubframe sf, int ch)
        {
            if (eparams.development_mode < 0)
                return;
            if (sf.type != SubframeType.LPC || sf.order > 30)
                return;
            int orig_window = sf.window;
            int orig_order = sf.order;
            int orig_shift = sf.shift;
            int orig_cbits = sf.cbits;
            uint orig_size = sf.size;
            var orig_coefs = stackalloc int[orig_order];
            for (int i = 0; i < orig_order; i++) orig_coefs[i] = sf.coefs[i];
            int orig_xx = -1;
            int orig_seq = 0;
            int maxxx = Math.Min(good_x[orig_order].Length, eparams.development_mode);
            var pmax = get_max_p_order(m_settings.MaxPartitionOrder, frame.blocksize, orig_order);
            var pmin = Math.Min(m_settings.MinPartitionOrder, pmax);
            ulong* sums = stackalloc ulong[(pmax + 1) * Flake.MAX_PARTITIONS];

            while (true)
            {
                var best_coefs = stackalloc int[orig_order];
                int best_shift = orig_shift;
                int best_cbits = orig_cbits;
                uint best_size = orig_size;
                int best_xx = -1;
                for (int xx = -1; xx < maxxx; xx++)
                {
                    int x = xx;
                    if (xx < 0)
                    {
                        if (orig_xx < 0 || maxxx < 1/*3*/)// || (orig_xx >> orig_order) != 0)
                            continue;
                        x = orig_xx;
                        orig_seq++;
                    }
                    else
                    {
                        orig_seq = 0;
                        if (orig_order < good_x.Length && good_x[orig_order] != null)
                            x = good_x[orig_order][xx];
                    }

                    frame.current.type = SubframeType.LPC;
                    frame.current.order = orig_order;
                    frame.current.window = orig_window;
                    frame.current.shift = orig_shift;
                    frame.current.cbits = orig_cbits;

                    if (((x >> orig_order) & 1) != 0)
                    {
                        frame.current.shift--;
                        frame.current.cbits--;
                        if (frame.current.shift < 0 || frame.current.cbits < 2)
                            continue;
                    }

                    ulong csum = 0;
                    int qmax = (1 << (frame.current.cbits - 1)) - 1;
                    for (int i = 0; i < frame.current.order; i++)
                    {
                        int shift = (x >> orig_order) & 1;
                        int increment = (x == 1 << orig_order) ? 0 : (((x >> i) & 1) << 1) - 1;
                        frame.current.coefs[i] = (orig_coefs[i] + (increment << orig_seq)) >> shift;
                        if (frame.current.coefs[i] < -(qmax + 1)) frame.current.coefs[i] = -(qmax + 1);
                        if (frame.current.coefs[i] > qmax) frame.current.coefs[i] = qmax;
                        csum += (ulong)Math.Abs(frame.current.coefs[i]);
                    }

                    fixed (int* coefs = frame.current.coefs)
                    {
                        if ((csum << frame.subframes[ch].obits) >= 1UL << 32)
                            lpc.encode_residual_long(frame.current.residual, frame.subframes[ch].samples, frame.blocksize, frame.current.order, coefs, frame.current.shift);
                        else
                            lpc.encode_residual(frame.current.residual, frame.subframes[ch].samples, frame.blocksize, frame.current.order, coefs, frame.current.shift);
                    }

                    var cur_size = calc_rice_params(frame.current.rc, pmin, pmax, frame.current.residual, (uint)frame.blocksize, (uint)frame.current.order, Settings.PCM.BitsPerSample);
                    frame.current.size = (uint)(frame.current.order * frame.subframes[ch].obits + 4 + 5 + frame.current.order * frame.current.cbits + 6 + (int)cur_size);

                    if (frame.current.size < best_size)
                    {
                        //var dif = best_size - frame.current.size;
                        for (int i = 0; i < frame.current.order; i++) best_coefs[i] = frame.current.coefs[i];
                        best_shift = frame.current.shift;
                        best_cbits = frame.current.cbits;
                        best_size = frame.current.size;
                        best_xx = x;
                        frame.ChooseBestSubframe(ch);
                        //if (dif > orig_order * 5)
                        //    break;
                    }

                    if (xx < 0 && best_size < orig_size)
                        break;
                }

                if (best_size < orig_size)
                {
                    //if (best_xx >= 0) best_x[order, best_xx]++;
                    //if (orig_size != 0x7FFFFFFF)
                    //    System.Console.Write(string.Format(" {0}[{1:x}]", orig_size - best_size, best_xx));
                    for (int i = 0; i < orig_order; i++) orig_coefs[i] = best_coefs[i];
                    orig_shift = best_shift;
                    orig_cbits = best_cbits;
                    orig_size = best_size;
                    orig_xx = best_xx;
                }
                else
                {
                    break;
                }
            }

            //if (orig_size != 0x7FFFFFFF)
            //    System.Console.WriteLine();

            //if (frame_count % 0x400 == 0)
            //{
            //    for (int o = 0; o < best_x.GetLength(0); o++)
            //    {
            //        //for (int x = 0; x <= (1 << o); x++)
            //        //    if (best_x[o, x] != 0)
            //        //        System.Console.WriteLine(string.Format("{0:x2}\t{1:x4}\t{2}", o, x, best_x[o, x]));
            //        var s = new List<KeyValuePair<int, int>>();
            //        for (int x = 0; x < (1 << o); x++)
            //            if (best_x[o, x] != 0)
            //                s.Add(new KeyValuePair<int, int>(x, best_x[o, x]));
            //        s.Sort((x, y) => y.Value.CompareTo(x.Value));
            //        foreach (var x in s)
            //            System.Console.WriteLine(string.Format("{0:x2}\t{1:x4}\t{2}", o, x.Key, x.Value));
            //        int i = 0;
            //        foreach (var x in s)
            //        {
            //            System.Console.Write(string.Format(o <= 8 ? "0x{0:x2}," : "0x{0:x3},", x.Key));
            //            if ((++i) % 16 == 0)
            //                System.Console.WriteLine();
            //        }
            //        System.Console.WriteLine();
            //    }
            //}
        }

        public static void SetCoefs(int order, int[] coefs)
        {
            good_x[order] = new int[coefs.Length];
            for (int i = 0; i < coefs.Length; i++)
                good_x[order][i] = coefs[i];
        }

        unsafe void encode_residual_lpc_sub(FlacFrame frame, float* lpcs, int iWindow, int order, int ch)
        {
            // select LPC precision based on block size
            uint lpc_precision;
            if (frame.blocksize <= 192) lpc_precision = 7U;
            else if (frame.blocksize <= 384) lpc_precision = 8U;
            else if (frame.blocksize <= 576) lpc_precision = 9U;
            else if (frame.blocksize <= 1152) lpc_precision = 10U;
            else if (frame.blocksize <= 2304) lpc_precision = 11U;
            else if (frame.blocksize <= 4608) lpc_precision = 12U;
            else if (frame.blocksize <= 8192) lpc_precision = 13U;
            else if (frame.blocksize <= 16384) lpc_precision = 14U;
            else lpc_precision = 15;

            for (int i_precision = eparams.lpc_min_precision_search; i_precision <= eparams.lpc_max_precision_search && lpc_precision + i_precision < 16; i_precision++)
                // check if we already calculated with this order, window and precision
                if ((frame.subframes[ch].lpc_ctx[iWindow].done_lpcs[i_precision] & (1U << (order - 1))) == 0)
                {
                    frame.subframes[ch].lpc_ctx[iWindow].done_lpcs[i_precision] |= (1U << (order - 1));

                    uint cbits = lpc_precision + (uint)i_precision;

                    frame.current.type = SubframeType.LPC;
                    frame.current.order = order;
                    frame.current.window = iWindow;
                    frame.current.cbits = (int)cbits;

                    fixed (int* coefs = frame.current.coefs)
                    {
                        lpc.quantize_lpc_coefs(lpcs + (frame.current.order - 1) * lpc.MAX_LPC_ORDER,
                            frame.current.order, cbits, coefs, out frame.current.shift, 15, 0);

                        if (frame.current.shift < 0 || frame.current.shift > 15)
                            throw new Exception("negative shift");

                        ulong csum = 0;
                        for (int i = frame.current.order; i > 0; i--)
                            csum += (ulong)Math.Abs(coefs[i - 1]);

                        if ((csum << frame.subframes[ch].obits) >= 1UL << 32)
                            lpc.encode_residual_long(frame.current.residual, frame.subframes[ch].samples, frame.blocksize, frame.current.order, coefs, frame.current.shift);
                        else
                            lpc.encode_residual(frame.current.residual, frame.subframes[ch].samples, frame.blocksize, frame.current.order, coefs, frame.current.shift);

                    }
                    int pmax = get_max_p_order(m_settings.MaxPartitionOrder, frame.blocksize, frame.current.order);
                    int pmin = Math.Min(m_settings.MinPartitionOrder, pmax);
                    uint best_size = calc_rice_params(frame.current.rc, pmin, pmax, frame.current.residual, (uint)frame.blocksize, (uint)frame.current.order, Settings.PCM.BitsPerSample);
                    // not working
                    //for (int o = 1; o <= frame.current.order; o++)
                    //{
                    //    if (frame.current.coefs[o - 1] > -(1 << frame.current.shift))
                    //    {
                    //        for (int i = o; i < frame.blocksize; i++)
                    //            frame.current.residual[i] += frame.subframes[ch].samples[i - o] >> frame.current.shift;
                    //        frame.current.coefs[o - 1]--;
                    //        uint new_size = calc_rice_params(ref frame.current.rc, pmin, pmax, frame.current.residual, (uint)frame.blocksize, (uint)frame.current.order);
                    //        if (new_size > best_size)
                    //        {
                    //            for (int i = o; i < frame.blocksize; i++)
                    //                frame.current.residual[i] -= frame.subframes[ch].samples[i - o] >> frame.current.shift;
                    //            frame.current.coefs[o - 1]++;
                    //        }
                    //    }
                    //}
                    frame.current.size = (uint)(frame.current.order * frame.subframes[ch].obits + 4 + 5 + frame.current.order * (int)cbits + 6 + (int)best_size);
                    frame.ChooseBestSubframe(ch);
                    //if (frame.current.size >= frame.subframes[ch].best.size)
                    //    postprocess_coefs(frame, frame.current, ch);
                    //else
                    //{
                    //    frame.ChooseBestSubframe(ch);
                    //    postprocess_coefs(frame, frame.subframes[ch].best, ch);
                    //}
                }
        }

		unsafe void encode_residual_fixed_sub(FlacFrame frame, int order, int ch)
		{
			if ((frame.subframes[ch].done_fixed & (1U << order)) != 0)
				return; // already calculated;

			frame.current.order = order;
			frame.current.type = SubframeType.Fixed;

			encode_residual_fixed(frame.current.residual, frame.subframes[ch].samples, frame.blocksize, frame.current.order);

            int pmax = get_max_p_order(m_settings.MaxPartitionOrder, frame.blocksize, frame.current.order);
            int pmin = Math.Min(m_settings.MinPartitionOrder, pmax);
			frame.current.size = (uint)(frame.current.order * frame.subframes[ch].obits) + 6
				+ calc_rice_params(frame.current.rc, pmin, pmax, frame.current.residual, (uint)frame.blocksize, (uint)frame.current.order, Settings.PCM.BitsPerSample);

			frame.subframes[ch].done_fixed |= (1U << order);

			frame.ChooseBestSubframe(ch);
		}

		unsafe void encode_residual(FlacFrame frame, int ch, PredictionType predict, OrderMethod omethod, int pass, int best_window)
		{
			int* smp = frame.subframes[ch].samples;
			int i, n = frame.blocksize;
			// save best.window, because we can overwrite it later with fixed frame

			// CONSTANT
			for (i = 1; i < n; i++)
			{
				if (smp[i] != smp[0]) break;
			}
			if (i == n)
			{
				frame.subframes[ch].best.type = SubframeType.Constant;
				frame.subframes[ch].best.residual[0] = smp[0];
				frame.subframes[ch].best.size = (uint)frame.subframes[ch].obits;
				return;
			}

			// VERBATIM
			frame.current.type = SubframeType.Verbatim;
			frame.current.size = (uint)(frame.subframes[ch].obits * frame.blocksize);
			frame.ChooseBestSubframe(ch);

			if (n < 5 || predict == PredictionType.None)
				return;

			// LPC
            if (n > m_settings.MaxLPCOrder &&
			   (predict == PredictionType.Levinson ||
				predict == PredictionType.Search)
				//predict == PredictionType.Search ||
				//(pass == 2 && frame.subframes[ch].best.type == SubframeType.LPC))
				)
			{
				float* lpcs = stackalloc float[lpc.MAX_LPC_ORDER * lpc.MAX_LPC_ORDER];
                int min_order = m_settings.MinLPCOrder;
                int max_order = m_settings.MaxLPCOrder;

				for (int iWindow = 0; iWindow < _windowcount; iWindow++)
				{
					if (best_window != -1 && iWindow != best_window)
						continue;

					LpcContext lpc_ctx = frame.subframes[ch].lpc_ctx[iWindow];

					lpc_ctx.GetReflection(max_order, smp, n, frame.window_buffer + iWindow * Flake.MAX_BLOCKSIZE * 2);
					lpc_ctx.ComputeLPC(lpcs);

					//int frameSize = n;
					//float* F = stackalloc float[frameSize];
					//float* B = stackalloc float[frameSize];
					//float* PE = stackalloc float[max_order + 1];
					//float* arp = stackalloc float[max_order];
					//float* rc = stackalloc float[max_order];

					//for (int j = 0; j < frameSize; j++)
					//    F[j] = B[j] = smp[j];

					//for (int K = 1; K <= max_order; K++)
					//{
					//    // BURG:
					//    float denominator = 0.0f;
					//    //float denominator = F[K - 1] * F[K - 1] + B[frameSize - K] * B[frameSize - K];
					//    for (int j = 0; j < frameSize - K; j++)
					//        denominator += F[j + K] * F[j + K] + B[j] * B[j];
					//    denominator /= 2;

					//    // Estimate error
					//    PE[K - 1] = denominator / (frameSize - K);

					//    float reflectionCoeff = 0.0f;
					//    for (int j = 0; j < frameSize - K; j++)
					//        reflectionCoeff += F[j + K] * B[j];
					//    reflectionCoeff /= denominator;
					//    rc[K - 1] = arp[K - 1] = reflectionCoeff;

					//    // Levinson-Durbin
					//    for (int j = 0; j < (K - 1) >> 1; j++)
					//    {
					//        float arptmp = arp[j];
					//        arp[j] -= reflectionCoeff * arp[K - 2 - j];
					//        arp[K - 2 - j] -= reflectionCoeff * arptmp;
					//    }
					//    if (((K - 1) & 1) != 0)
					//        arp[(K - 1) >> 1] -= reflectionCoeff * arp[(K - 1) >> 1];

					//    for (int j = 0; j < frameSize - K; j++)
					//    {
					//        float f = F[j + K];
					//        float b = B[j];
					//        F[j + K] = f - reflectionCoeff * b;
					//        B[j] = b - reflectionCoeff * f;
					//    }

					//    for (int j = 0; j < K; j++)
					//        lpcs[(K - 1) * lpc.MAX_LPC_ORDER + j] = (float)arp[j];
					//}

					switch (omethod)
					{
						case OrderMethod.Akaike:
							//lpc_ctx.SortOrdersAkaike(frame.blocksize, eparams.estimation_depth, max_order, 7.1, 0.0);
							lpc_ctx.SortOrdersAkaike(frame.blocksize, eparams.estimation_depth, min_order, max_order, 4.5, 0.0);
							break;
						default:
							throw new Exception("unknown order method");
					}

					for (i = 0; i < eparams.estimation_depth && i < max_order; i++)
						encode_residual_lpc_sub(frame, lpcs, iWindow, lpc_ctx.best_orders[i], ch);
                }

                postprocess_coefs(frame, frame.subframes[ch].best, ch);
            }
        
            // FIXED
            if (predict == PredictionType.Fixed ||
                (predict == PredictionType.Search && pass != 1) ||
                //predict == PredictionType.Search ||
                //(pass == 2 && frame.subframes[ch].best.type == SubframeType.Fixed) ||
                (n > m_settings.MaxFixedOrder && n <= m_settings.MaxLPCOrder))
            {
                int max_fixed_order = Math.Min(m_settings.MaxFixedOrder, 4);
                int min_fixed_order = Math.Min(m_settings.MinFixedOrder, max_fixed_order);

                for (i = min_fixed_order; i <= max_fixed_order; i++)
                    encode_residual_fixed_sub(frame, i, ch);
            }

        }

		unsafe void output_frame_header(FlacFrame frame, BitWriter bitwriter)
		{
			bitwriter.writebits(15, 0x7FFC);
			bitwriter.writebits(1, eparams.variable_block_size > 0 ? 1 : 0);
			bitwriter.writebits(4, frame.bs_code0);
			bitwriter.writebits(4, sr_code0);
			if (frame.ch_mode == ChannelMode.NotStereo)
				bitwriter.writebits(4, ch_code);
			else
				bitwriter.writebits(4, (int) frame.ch_mode);
			bitwriter.writebits(3, bps_code);
			bitwriter.writebits(1, 0);
			bitwriter.write_utf8(frame_count);

			// custom block size
			if (frame.bs_code1 >= 0)
			{
				if (frame.bs_code1 < 256)
					bitwriter.writebits(8, frame.bs_code1);
				else
					bitwriter.writebits(16, frame.bs_code1);
			}

			// custom sample rate
			if (sr_code1 > 0)
			{
				if (sr_code1 < 256)
					bitwriter.writebits(8, sr_code1);
				else
					bitwriter.writebits(16, sr_code1);
			}

			// CRC-8 of frame header
			bitwriter.flush();
			byte crc = crc8.ComputeChecksum(frame_buffer, 0, bitwriter.Length);
			bitwriter.writebits(8, crc);
		}

		unsafe void output_residual(FlacFrame frame, BitWriter bitwriter, FlacSubframeInfo sub)
		{
			// rice-encoded block
			bitwriter.writebits(2, sub.best.rc.coding_method);

			// partition order
			int porder = sub.best.rc.porder;
			int psize = frame.blocksize >> porder;
			//assert(porder >= 0);
			bitwriter.writebits(4, porder);
			int res_cnt = psize - sub.best.order;

			int rice_len = 4 + sub.best.rc.coding_method;
			// residual
			int j = sub.best.order;
			fixed (byte* fixbuf = &frame_buffer[0])
			for (int p = 0; p < (1 << porder); p++)
			{
				int k = sub.best.rc.rparams[p];
				bitwriter.writebits(rice_len, k);
				if (p == 1) res_cnt = psize;
				int cnt = Math.Min(res_cnt, frame.blocksize - j);
				bitwriter.write_rice_block_signed(fixbuf, k, sub.best.residual + j, cnt);
				j += cnt;
			}
		}

		unsafe void 
		output_subframe_constant(FlacFrame frame, BitWriter bitwriter, FlacSubframeInfo sub)
		{
			bitwriter.writebits_signed(sub.obits, sub.best.residual[0]);
		}

		unsafe void
		output_subframe_verbatim(FlacFrame frame, BitWriter bitwriter, FlacSubframeInfo sub)
		{
			int n = frame.blocksize;
			for (int i = 0; i < n; i++)
				bitwriter.writebits_signed(sub.obits, sub.samples[i]); 
			// Don't use residual here, because we don't copy samples to residual for verbatim frames.
		}

		unsafe void
		output_subframe_fixed(FlacFrame frame, BitWriter bitwriter, FlacSubframeInfo sub)
		{
			// warm-up samples
			for (int i = 0; i < sub.best.order; i++)
				bitwriter.writebits_signed(sub.obits, sub.best.residual[i]);

			// residual
			output_residual(frame, bitwriter, sub);
		}

		unsafe void
		output_subframe_lpc(FlacFrame frame, BitWriter bitwriter, FlacSubframeInfo sub)
		{
			// warm-up samples
			for (int i = 0; i < sub.best.order; i++)
				bitwriter.writebits_signed(sub.obits, sub.best.residual[i]);

			// LPC coefficients
			int cbits = 1;
			for (int i = 0; i < sub.best.order; i++)
				while (cbits < 16 && sub.best.coefs[i] != (sub.best.coefs[i] << (32 - cbits)) >> (32 - cbits))
					cbits++;
			bitwriter.writebits(4, cbits - 1);
			bitwriter.writebits_signed(5, sub.best.shift);
			for (int i = 0; i < sub.best.order; i++)
				bitwriter.writebits_signed(cbits, sub.best.coefs[i]);
			
			// residual
			output_residual(frame, bitwriter, sub);
		}

		unsafe void output_subframes(FlacFrame frame, BitWriter bitwriter)
		{
			for (int ch = 0; ch < channels; ch++)
			{
				FlacSubframeInfo sub = frame.subframes[ch];
				// subframe header
				int type_code = (int) sub.best.type;
				if (sub.best.type == SubframeType.Fixed)
					type_code |= sub.best.order;
				if (sub.best.type == SubframeType.LPC)
					type_code |= sub.best.order - 1;
				bitwriter.writebits(1, 0);
				bitwriter.writebits(6, type_code);
				bitwriter.writebits(1, sub.wbits != 0 ? 1 : 0);
				if (sub.wbits > 0)
					bitwriter.writebits((int)sub.wbits, 1);

				// subframe
				switch (sub.best.type)
				{
					case SubframeType.Constant:
						output_subframe_constant(frame, bitwriter, sub);
						break;
					case SubframeType.Verbatim:
						output_subframe_verbatim(frame, bitwriter, sub);
						break;
					case SubframeType.Fixed:
						output_subframe_fixed(frame, bitwriter, sub);
						break;
					case SubframeType.LPC:
						output_subframe_lpc(frame, bitwriter, sub);
						break;
				}
			}
		}

		void output_frame_footer(BitWriter bitwriter)
		{
			bitwriter.flush();
            ushort crc = bitwriter.get_crc16();
            bitwriter.writebits(16, crc);
			bitwriter.flush();
		}

		unsafe void encode_residual_pass1(FlacFrame frame, int ch, int best_window)
		{
            int max_prediction_order = m_settings.MaxLPCOrder;
            int max_fixed_order = m_settings.MaxFixedOrder;
            int min_fixed_order = m_settings.MinFixedOrder;
			int lpc_min_precision_search = eparams.lpc_min_precision_search;
			int lpc_max_precision_search = eparams.lpc_max_precision_search;
            int max_partition_order = m_settings.MaxPartitionOrder;
			int estimation_depth = eparams.estimation_depth;
            var development_mode = eparams.development_mode;
            m_settings.MinFixedOrder = 2;
            m_settings.MaxFixedOrder = 2;
			eparams.lpc_min_precision_search = eparams.lpc_max_precision_search;
            m_settings.MaxLPCOrder = Math.Min(m_settings.MaxLPCOrder, Math.Max(m_settings.MinLPCOrder, 8));
			eparams.estimation_depth = 1;
            eparams.development_mode = Math.Min(eparams.development_mode, -1);
            encode_residual(frame, ch, eparams.prediction_type, OrderMethod.Akaike, 1, best_window);
            m_settings.MinFixedOrder = min_fixed_order;
            m_settings.MaxFixedOrder = max_fixed_order;
            m_settings.MaxLPCOrder = max_prediction_order;
			eparams.lpc_min_precision_search = lpc_min_precision_search;
			eparams.lpc_max_precision_search = lpc_max_precision_search;
            m_settings.MaxPartitionOrder = max_partition_order;
			eparams.estimation_depth = estimation_depth;
            eparams.development_mode = development_mode;
		}

		unsafe void encode_residual_pass2(FlacFrame frame, int ch)
		{
			encode_residual(frame, ch, eparams.prediction_type, eparams.order_method, 2, estimate_best_window(frame, ch));
		}

		unsafe int estimate_best_window(FlacFrame frame, int ch)
		{
			if (_windowcount == 1) 
				return 0;
			switch (eparams.window_method)
			{
				case WindowMethod.Estimate:
					{
						int best_window = -1;
						double best_error = 0;
						int order = 2;
						for (int i = 0; i < _windowcount; i++)
						{
							frame.subframes[ch].lpc_ctx[i].GetReflection(order, frame.subframes[ch].samples, frame.blocksize, frame.window_buffer + i * Flake.MAX_BLOCKSIZE * 2);
							double err = frame.subframes[ch].lpc_ctx[i].prediction_error[order - 1] / frame.subframes[ch].lpc_ctx[i].autocorr_values[0];
							//double err = frame.subframes[ch].lpc_ctx[i].autocorr_values[0] / frame.subframes[ch].lpc_ctx[i].autocorr_values[2];
							if (best_window == -1 || best_error > err)
							{
								best_window = i;
								best_error = err;
							}
						}
						return best_window;
					}
				case WindowMethod.Evaluate:
					encode_residual_pass1(frame, ch, -1);
					return frame.subframes[ch].best.type == SubframeType.LPC ? frame.subframes[ch].best.window : -1;
				case WindowMethod.Search:
					return -1;
			}
			return -1;
		}

		unsafe void estimate_frame(FlacFrame frame, bool do_midside)
		{
			int subframes = do_midside ? channels * 2 : channels;

			switch (eparams.stereo_method)
			{
				case StereoMethod.Estimate:
					for (int ch = 0; ch < subframes; ch++)
					{
						LpcContext lpc_ctx = frame.subframes[ch].lpc_ctx[0];
						lpc_ctx.GetReflection(4, frame.subframes[ch].samples, frame.blocksize, frame.window_buffer);
						lpc_ctx.SortOrdersAkaike(frame.blocksize, 1, 1, 4, 4.5, 0.0);
                        frame.subframes[ch].best.size = (uint)Math.Max(0, lpc_ctx.Akaike(frame.blocksize, lpc_ctx.best_orders[0], 4.5, 0.0) + 7.1 * frame.subframes[ch].obits * m_settings.MaxLPCOrder);
					}
					break;
				case StereoMethod.Evaluate:
                    for (int ch = 0; ch < subframes; ch++)
                        encode_residual_pass1(frame, ch, 0);
					break;
				case StereoMethod.Search:
					for (int ch = 0; ch < subframes; ch++)
					    encode_residual_pass2(frame, ch);
					break;
			}
		}

		unsafe uint measure_frame_size(FlacFrame frame, bool do_midside)
		{
			// crude estimation of header/footer size
			uint total = (uint)(32 + ((BitReader.log2i(frame_count) + 4) / 5) * 8 + (eparams.variable_block_size != 0 ? 16 : 0) + 16);

			if (do_midside)
			{
				uint bitsBest = AudioSamples.UINT32_MAX;
				ChannelMode modeBest = ChannelMode.LeftRight;

				if (bitsBest > frame.subframes[2].best.size + frame.subframes[3].best.size)
				{
					bitsBest = frame.subframes[2].best.size + frame.subframes[3].best.size;
					modeBest = ChannelMode.MidSide;
				}
				if (bitsBest > frame.subframes[3].best.size + frame.subframes[1].best.size)
				{
					bitsBest = frame.subframes[3].best.size + frame.subframes[1].best.size;
					modeBest = ChannelMode.RightSide;
				}
				if (bitsBest > frame.subframes[3].best.size + frame.subframes[0].best.size)
				{
					bitsBest = frame.subframes[3].best.size + frame.subframes[0].best.size;
					modeBest = ChannelMode.LeftSide;
				}
				if (bitsBest > frame.subframes[0].best.size + frame.subframes[1].best.size)
				{
					bitsBest = frame.subframes[0].best.size + frame.subframes[1].best.size;
					modeBest = ChannelMode.LeftRight;
				}
				frame.ch_mode = modeBest;
				return total + bitsBest;
			}

			for (int ch = 0; ch < channels; ch++)
				total += frame.subframes[ch].best.size;
			return total;
		}

		unsafe void encode_estimated_frame(FlacFrame frame)
		{
			switch (eparams.stereo_method)
			{
				case StereoMethod.Estimate:
					for (int ch = 0; ch < channels; ch++)
					{
						frame.subframes[ch].best.size = AudioSamples.UINT32_MAX;
						encode_residual_pass2(frame, ch);
					}
					break;
				case StereoMethod.Evaluate:
					for (int ch = 0; ch < channels; ch++)
						encode_residual_pass2(frame, ch);
					break;
				case StereoMethod.Search:
					break;
			}
		}

		unsafe delegate void window_function(float* window, int size);

		unsafe void calculate_window(float* window, window_function func, WindowFunction flag)
		{
			if ((eparams.window_function & flag) == 0 || _windowcount == lpc.MAX_LPC_WINDOWS)
				return;
			int sz = _windowsize;
			float* pos1 = window + _windowcount * Flake.MAX_BLOCKSIZE * 2;
			float* pos = pos1;
			do
			{
				func(pos, sz);
				if ((sz & 1) != 0)
					break;
				pos += sz;
				sz >>= 1;
			} while (sz >= 32);
			double scale = 0.0;
			for (int i = 0; i < _windowsize; i++)
				scale += pos1[i] * pos1[i];
			windowScale[_windowcount] = scale;
			_windowcount++;
		}

		unsafe int encode_frame(out int size)
		{
			fixed (int* s = samplesBuffer, r = residualBuffer)
			fixed (float* window = windowBuffer)
			{
				frame.InitSize(m_blockSize, eparams.variable_block_size != 0);

				if (frame.blocksize != _windowsize && frame.blocksize > 4)
				{
					_windowsize = frame.blocksize;
					_windowcount = 0;
					calculate_window(window, lpc.window_welch, WindowFunction.Welch);
					calculate_window(window, lpc.window_tukey, WindowFunction.Tukey);
					calculate_window(window, lpc.window_flattop, WindowFunction.Flattop);
					calculate_window(window, lpc.window_hann, WindowFunction.Hann);
					calculate_window(window, lpc.window_bartlett, WindowFunction.Bartlett);
					if (_windowcount == 0)
						throw new Exception("invalid windowfunction");
				}

				if (channels != 2 || frame.blocksize <= 32 || eparams.stereo_method == StereoMethod.Independent)
				{
					frame.window_buffer = window;
					frame.current.residual = r + channels * Flake.MAX_BLOCKSIZE;
					frame.ch_mode = channels != 2 ? ChannelMode.NotStereo : ChannelMode.LeftRight;
					for (int ch = 0; ch < channels; ch++)
						frame.subframes[ch].Init(s + ch * Flake.MAX_BLOCKSIZE, r + ch * Flake.MAX_BLOCKSIZE,
                            Settings.PCM.BitsPerSample, get_wasted_bits(s + ch * Flake.MAX_BLOCKSIZE, frame.blocksize));

					for (int ch = 0; ch < channels; ch++)
						encode_residual_pass2(frame, ch);
				}
				else
				{
					//channel_decorrelation(s, s + Flake.MAX_BLOCKSIZE, s + 2 * Flake.MAX_BLOCKSIZE, s + 3 * Flake.MAX_BLOCKSIZE, frame.blocksize);
					frame.window_buffer = window;
					frame.current.residual = r + 4 * Flake.MAX_BLOCKSIZE;
					for (int ch = 0; ch < 4; ch++)
						frame.subframes[ch].Init(s + ch * Flake.MAX_BLOCKSIZE, r + ch * Flake.MAX_BLOCKSIZE,
                            Settings.PCM.BitsPerSample + (ch == 3 ? 1 : 0), get_wasted_bits(s + ch * Flake.MAX_BLOCKSIZE, frame.blocksize));

					//for (int ch = 0; ch < 4; ch++)
					//    for (int iWindow = 0; iWindow < _windowcount; iWindow++)
					//        frame.subframes[ch].lpc_ctx[iWindow].GetReflection(32, frame.subframes[ch].samples, frame.blocksize, frame.window_buffer + iWindow * Flake.MAX_BLOCKSIZE * 2);

					estimate_frame(frame, true);
					uint fs = measure_frame_size(frame, true);

					if (0 != eparams.variable_block_size)
					{
						FlacFrame frame2 = new FlacFrame(channels * 2);
						FlacFrame frame3 = new FlacFrame(channels * 2);
						int tumbler = 1;
						while ((frame.blocksize & 1) == 0 && frame.blocksize >= 1024)
						{
							frame2.InitSize(frame.blocksize / 2, true);
							frame2.window_buffer = frame.window_buffer + frame.blocksize;
							frame2.current.residual = r + tumbler * 5 * Flake.MAX_BLOCKSIZE;
							for (int ch = 0; ch < 4; ch++)
								frame2.subframes[ch].Init(frame.subframes[ch].samples, frame2.current.residual + (ch + 1) * frame2.blocksize,
									frame.subframes[ch].obits + frame.subframes[ch].wbits, frame.subframes[ch].wbits);
							estimate_frame(frame2, true);
							uint fs2 = measure_frame_size(frame2, true);
							uint fs3 = fs2;
							if (eparams.variable_block_size == 2 || eparams.variable_block_size == 4)
							{
								frame3.InitSize(frame2.blocksize, true);
								frame3.window_buffer = frame2.window_buffer;
								frame3.current.residual = frame2.current.residual + 5 * frame2.blocksize;
								for (int ch = 0; ch < 4; ch++)
									frame3.subframes[ch].Init(frame2.subframes[ch].samples + frame2.blocksize, frame3.current.residual + (ch + 1) * frame3.blocksize,
										frame.subframes[ch].obits + frame.subframes[ch].wbits, frame.subframes[ch].wbits);
								estimate_frame(frame3, true);
								fs3 = measure_frame_size(frame3, true);
							}
							if (fs2 + fs3 > fs)
								break;
							FlacFrame tmp = frame;
							frame = frame2;
							frame2 = tmp;
							fs = fs2;
							if (eparams.variable_block_size <= 2)
								break;
							tumbler = 1 - tumbler;
						}
					}

					frame.ChooseSubframes();
					encode_estimated_frame(frame);
				}

				BitWriter bitwriter = new BitWriter(frame_buffer, 0, max_frame_size);

				output_frame_header(frame, bitwriter);
				output_subframes(frame, bitwriter);
				output_frame_footer(bitwriter);

				if (bitwriter.Length >= max_frame_size)
					throw new Exception("buffer overflow");

				if (frame_buffer != null)
				{
					if (eparams.variable_block_size > 0)
						frame_count += frame.blocksize;
					else
						frame_count++;
				}
				size = frame.blocksize;
				return bitwriter.Length;
			}
		}

		unsafe int output_frame()
		{
			if (verify != null)
			{
				fixed (int* s = verifyBuffer, r = samplesBuffer)
					for (int ch = 0; ch < channels; ch++)
                        AudioSamples.MemCpy(s + ch * Flake.MAX_BLOCKSIZE, r + ch * Flake.MAX_BLOCKSIZE, m_blockSize);
			}

			int fs, bs;
            //if (0 != eparams.variable_block_size && 0 == (m_blockSize & 7) && m_blockSize >= 128)
			//    fs = encode_frame_vbs();
			//else
			fs = encode_frame(out bs);

			if (seek_table != null && _IO.CanSeek)
			{
				for (int sp = 0; sp < seek_table.Length; sp++)
				{
					if (seek_table[sp].framesize != 0)
						continue;
					if (seek_table[sp].number > _position + bs)
						break;
					if (seek_table[sp].number >= _position)
					{
						seek_table[sp].number = _position;
						seek_table[sp].offset = _IO.Position - first_frame_offset;
						seek_table[sp].framesize = bs;
					}
				}
			}

			_position += bs;
			_IO.Write(frame_buffer, 0, fs);
			_totalSize += fs;

			if (verify != null)
			{
				int decoded = verify.DecodeFrame(frame_buffer, 0, fs);
				if (decoded != fs || verify.Remaining != bs)
					throw new Exception(Properties.Resources.ExceptionValidationFailed);
				fixed (int* s = verifyBuffer, r = verify.Samples)
				{
					for (int ch = 0; ch < channels; ch++)
						if (AudioSamples.MemCmp(s + ch * Flake.MAX_BLOCKSIZE, r + ch * Flake.MAX_BLOCKSIZE, bs))
							throw new Exception(Properties.Resources.ExceptionValidationFailed);
				}
			}

            if (bs < m_blockSize)
			{
				for (int ch = 0; ch < (channels == 2 ? 4 : channels); ch++)
                    Buffer.BlockCopy(samplesBuffer, (bs + ch * Flake.MAX_BLOCKSIZE) * sizeof(int), samplesBuffer, ch * Flake.MAX_BLOCKSIZE * sizeof(int), (m_blockSize - bs) * sizeof(int));
				//fixed (int* s = samplesBuffer)
				//    for (int ch = 0; ch < channels; ch++)
                //        AudioSamples.MemCpy(s + ch * Flake.MAX_BLOCKSIZE, s + bs + ch * Flake.MAX_BLOCKSIZE, m_blockSize - bs);
			}

			samplesInBuffer -= bs;

			return bs;
		}

		public void Write(AudioBuffer buff)
		{
			if (!inited)
			{
				if (_IO == null)
					_IO = new FileStream(_path, FileMode.Create, FileAccess.Write, FileShare.Read);
                inited = true;
                int header_size = flake_encode_init();
				_IO.Write(header, 0, header_size);
				if (_IO.CanSeek)
					first_frame_offset = _IO.Position;
			}

			buff.Prepare(this);

			int pos = 0;
			while (pos < buff.Length)
			{
                int block = Math.Min(buff.Length - pos, m_blockSize - samplesInBuffer);

				copy_samples(buff.Samples, pos, block);

				pos += block;

                while (samplesInBuffer >= m_blockSize)
					output_frame();
			}

			if (md5 != null)
				md5.TransformBlock(buff.Bytes, 0, buff.ByteLength, null, 0);
		}

		public string Path { get { return _path; } }

        public static string Vendor
        {
            get
            {
                var version = typeof(FlakeWriter).Assembly.GetName().Version;
                return vendor_string ?? "CUETools " + version.Major + "." + version.Minor + "." + version.Build;
            }
            set
            {
                vendor_string = value;
            }
        }

        static string vendor_string = null;

		int select_blocksize(int samplerate, int time_ms)
		{
			int blocksize = Flake.flac_blocksizes[1];
			int target = (samplerate * time_ms) / 1000;
			if (eparams.variable_block_size > 0)
			{
				blocksize = 1024;
				while (target >= blocksize)
					blocksize <<= 1;
				return blocksize >> 1;
			}

            for (int i = 8; i < Flake.flac_blocksizes.Length - 1; i++)
				if (target >= Flake.flac_blocksizes[i] && Flake.flac_blocksizes[i] > blocksize)
				{
					blocksize = Flake.flac_blocksizes[i];
				}
			return blocksize;
		}

		void write_streaminfo(byte[] header, int pos, int last)
		{
			Array.Clear(header, pos, 38);
			BitWriter bitwriter = new BitWriter(header, pos, 38);

			// metadata header
			bitwriter.writebits(1, last);
			bitwriter.writebits(7, (int)MetadataType.StreamInfo);
			bitwriter.writebits(24, 34);

			if (eparams.variable_block_size > 0)
				bitwriter.writebits(16, 0);
			else
                bitwriter.writebits(16, m_blockSize);

            bitwriter.writebits(16, m_blockSize);
			bitwriter.writebits(24, 0);
			bitwriter.writebits(24, max_frame_size);
            bitwriter.writebits(20, Settings.PCM.SampleRate);
			bitwriter.writebits(3, channels - 1);
            bitwriter.writebits(5, Settings.PCM.BitsPerSample - 1);

			// total samples
			if (sample_count > 0)
			{
				bitwriter.writebits(4, 0);
				bitwriter.writebits(32, sample_count);
			}
			else
			{
				bitwriter.writebits(4, 0);
				bitwriter.writebits(32, 0);
			}
			bitwriter.flush();
		}

		/**
		 * Write vorbis comment metadata block to byte array.
		 * Just writes the vendor string for now.
	     */
		int write_vorbis_comment(byte[] comment, int pos, int last)
		{
			BitWriter bitwriter = new BitWriter(comment, pos, 4);
			Encoding enc = new ASCIIEncoding();
			int vendor_len = enc.GetBytes(Vendor, 0, Vendor.Length, comment, pos + 8);

			// metadata header
			bitwriter.writebits(1, last);
			bitwriter.writebits(7, (int)MetadataType.VorbisComment);
			bitwriter.writebits(24, vendor_len + 8);

			comment[pos + 4] = (byte)(vendor_len & 0xFF);
			comment[pos + 5] = (byte)((vendor_len >> 8) & 0xFF);
			comment[pos + 6] = (byte)((vendor_len >> 16) & 0xFF);
			comment[pos + 7] = (byte)((vendor_len >> 24) & 0xFF);
			comment[pos + 8 + vendor_len] = 0;
			comment[pos + 9 + vendor_len] = 0;
			comment[pos + 10 + vendor_len] = 0;
			comment[pos + 11 + vendor_len] = 0;
			bitwriter.flush();
			return vendor_len + 12;
		}

		int write_seekpoints(byte[] header, int pos, int last)
		{
			seek_table_offset = pos + 4;

			BitWriter bitwriter = new BitWriter(header, pos, 4 + 18 * seek_table.Length);

			// metadata header
			bitwriter.writebits(1, last);
			bitwriter.writebits(7, (int)MetadataType.Seektable);
			bitwriter.writebits(24, 18 * seek_table.Length);
			for (int i = 0; i < seek_table.Length; i++)
			{
				bitwriter.writebits(Flake.FLAC__STREAM_METADATA_SEEKPOINT_SAMPLE_NUMBER_LEN, (ulong)seek_table[i].number);
				bitwriter.writebits(Flake.FLAC__STREAM_METADATA_SEEKPOINT_STREAM_OFFSET_LEN, (ulong)seek_table[i].offset);
				bitwriter.writebits(Flake.FLAC__STREAM_METADATA_SEEKPOINT_FRAME_SAMPLES_LEN, seek_table[i].framesize);
			}
			bitwriter.flush();
			return 4 + 18 * seek_table.Length;
		}

		/**
		 * Write padding metadata block to byte array.
		 */
		int
		write_padding(byte[] padding, int pos, int last, int padlen)
		{
			BitWriter bitwriter = new BitWriter(padding, pos, 4);

			// metadata header
			bitwriter.writebits(1, last);
			bitwriter.writebits(7, (int)MetadataType.Padding);
			bitwriter.writebits(24, padlen);

            bitwriter.flush();
            return padlen + 4;
		}

		int write_headers()
		{
			int header_size = 0;
			int last = 0;

			// stream marker
			header[0] = 0x66;
			header[1] = 0x4C;
			header[2] = 0x61;
			header[3] = 0x43;
			header_size += 4;

			// streaminfo
			write_streaminfo(header, header_size, last);
			header_size += 38;

			// seek table
			if (_IO.CanSeek && seek_table != null)
				header_size += write_seekpoints(header, header_size, last);

			// vorbis comment
			if (m_settings.Padding == 0) last = 1;
			header_size += write_vorbis_comment(header, header_size, last);

			// padding
			if (m_settings.Padding > 0)
			{
				last = 1;
				header_size += write_padding(header, header_size, last, m_settings.Padding);
			}

			return header_size;
		}

		int flake_encode_init()
		{
			int i, header_len;

			//if(flake_validate_params(s) < 0)

			ch_code = channels - 1;

			// find samplerate in table
			for (i = 1; i < 12; i++)
			{
                if (Settings.PCM.SampleRate == Flake.flac_samplerates[i])
				{
					sr_code0 = i;
					break;
				}
			}

			// if not in table, samplerate is non-standard
			if (i == 12)
				throw new Exception("non-standard samplerate");

			for (i = 1; i < 8; i++)
			{
                if (Settings.PCM.BitsPerSample == Flake.flac_bitdepths[i])
				{
					bps_code = i;
					break;
				}
			}
			if (i == 8)
				throw new Exception("non-standard bps");

            m_blockSize = m_settings.BlockSize != 0 ? m_settings.BlockSize :
                select_blocksize(Settings.PCM.SampleRate, eparams.block_time_ms);

			// set maximum encoded frame size (if larger, re-encodes in verbatim mode)
			if (channels == 2)
                max_frame_size = 16 + ((m_blockSize * (Settings.PCM.BitsPerSample + Settings.PCM.BitsPerSample + 1) + 7) >> 3);
			else
                max_frame_size = 16 + ((m_blockSize * channels * Settings.PCM.BitsPerSample + 7) >> 3);

			if (_IO.CanSeek && eparams.do_seektable && sample_count > 0)
			{
                int seek_points_distance = Settings.PCM.SampleRate * 10;
				int num_seek_points = 1 + sample_count / seek_points_distance; // 1 seek point per 10 seconds
				if (sample_count % seek_points_distance == 0)
					num_seek_points--;
				seek_table = new SeekPoint[num_seek_points];
				for (int sp = 0; sp < num_seek_points; sp++)
				{
					seek_table[sp].framesize = 0;
					seek_table[sp].offset = 0;
					seek_table[sp].number = sp * seek_points_distance;
				}
			}

			// output header bytes
			header = new byte[m_settings.Padding + 1024 + (seek_table == null ? 0 : seek_table.Length * 18)];
			header_len = write_headers();

			// initialize CRC & MD5
			if (_IO.CanSeek && m_settings.DoMD5)
				md5 = new MD5CryptoServiceProvider();

			if (m_settings.DoVerify)
			{
                verify = new FlakeReader(Settings.PCM);
				verifyBuffer = new int[Flake.MAX_BLOCKSIZE * channels];
			}

			frame_buffer = new byte[max_frame_size];

			return header_len;
		}
	}

	struct FlakeEncodeParams
	{
		// prediction order selection method
		// set by user prior to calling flake_encode_init
		// if set to less than 0, it is chosen based on compression.
		// valid values are 0 to 5
		// 0 = use maximum order only
		// 1 = use estimation
		// 2 = 2-level
		// 3 = 4-level
		// 4 = 8-level
		// 5 = full search
		// 6 = log search
		public OrderMethod order_method;

		// stereo decorrelation method
		// set by user prior to calling flake_encode_init
		// if set to less than 0, it is chosen based on compression.
		// valid values are 0 to 2
		// 0 = independent L+R channels
		// 1 = mid-side encoding
		public StereoMethod stereo_method;

		public WindowMethod window_method;

		// block time in milliseconds
		// set by the user prior to calling flake_encode_init
		// used to calculate block_size based on sample rate
		// can also be changed by user before encoding a frame
		public int block_time_ms;

		// Number of LPC orders to try (for estimate mode)
		// set by user prior to calling flake_encode_init
		// if set to less than 0, it is chosen based on compression.
		// valid values are 1 to 32 
		public int estimation_depth;

		// type of linear prediction
		// set by user prior to calling flake_encode_init
		public PredictionType prediction_type;

		// whether to use variable block sizes
		// set by user prior to calling flake_encode_init
		// 0 = fixed block size
		// 1 = variable block size
		public int variable_block_size;

		// whether to try various lpc_precisions
		// 0 - use only one precision
		// 1 - try two precisions
		public int lpc_max_precision_search;

		public int lpc_min_precision_search;

		public WindowFunction window_function;

		public bool do_seektable;

        public int development_mode;

		public int flake_set_defaults(FlakeWriterSettings settings)
		{
			// default to level 7 params
			window_function = WindowFunction.Flattop | WindowFunction.Tukey;
			order_method = OrderMethod.Akaike;
			stereo_method = StereoMethod.Evaluate;
			window_method = WindowMethod.Evaluate;
			block_time_ms = 105;			
			prediction_type = PredictionType.Search;
            estimation_depth = 1;
            variable_block_size = 0;
			lpc_min_precision_search = 1;
			lpc_max_precision_search = 1;
			do_seektable = true;
            development_mode = -1;

			// differences from level 7
			switch (settings.EncoderModeIndex)
			{
				case 0:
					block_time_ms = 53;
					prediction_type = PredictionType.Fixed;
					stereo_method = StereoMethod.Independent;
					break;
				case 1:
					prediction_type = PredictionType.Levinson;
					stereo_method = StereoMethod.Independent;
					window_function = WindowFunction.Bartlett;
					break;
				case 2:
					stereo_method = StereoMethod.Independent;
					window_function = WindowFunction.Bartlett;
					break;
				case 3:
					stereo_method = StereoMethod.Estimate;
					window_function = WindowFunction.Bartlett;
					break;
				case 4:
					stereo_method = StereoMethod.Estimate;
					window_function = WindowFunction.Bartlett;
					break;
				case 5:
					stereo_method = StereoMethod.Estimate;
					window_method = WindowMethod.Estimate;
					break;
				case 6:
					stereo_method = StereoMethod.Estimate;
					break;
				case 7:
					break;
				case 8:
					estimation_depth = 2;
					lpc_min_precision_search = 0;
					break;
				case 9:
					window_function = WindowFunction.Bartlett;
					break;
				case 10:
					//lpc_max_precision_search = 2;
					break;
				case 11:
					estimation_depth = 5;
					//lpc_max_precision_search = 2;
					variable_block_size = 4;
					break;
			}

			return 0;
		}
	}
}