WMADecoder now supports multichannel audio

Better WAVE_FORMAT_EXTENSIBLE & channelMask support in WMA & WAV
2025-12-16 18:14:25 +00:00 · 2013-04-14 16:54:19 -04:00
parent 40f6482077
commit 563f066646
9 changed files with 159 additions and 87 deletions
--- a/CUETools.Codecs.WMA/WaveFormatExtensible.cs
+++ b/CUETools.Codecs.WMA/WaveFormatExtensible.cs
@@ -0,0 +1,91 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Runtime.InteropServices;
+using WindowsMediaLib.Defs;
+
+namespace CUETools.Codecs.WMA
+{
+    /// <summary>
+    /// From WAVEFORMATEXTENSIBLE
+    /// </summary>
+    [StructLayout(LayoutKind.Sequential, Pack = 2)]
+    public struct WaveFormatExtensible
+    {
+        public const ushort WAVE_FORMAT_EXTENSIBLE = 0xFFFE;
+        public const ushort WAVE_FORMAT_PCM = 1;
+
+        public WaveFormatExtensible(AudioPCMConfig pcm)
+        {
+            this.nChannels = (short)pcm.ChannelCount;
+            this.nSamplesPerSec = pcm.SampleRate;
+            this.nBlockAlign = (short)pcm.BlockAlign;
+            this.wBitsPerSample = (short)pcm.BitsPerSample;
+            if ((pcm.BitsPerSample == 8 || pcm.BitsPerSample == 16 || pcm.BitsPerSample == 24) &&
+                (pcm.ChannelCount == 1 || pcm.ChannelCount == 2))
+            {
+                this.wFormatTag = unchecked((short)WAVE_FORMAT_PCM);
+                this.cbSize = 0;
+                // just to make compiler happy
+                this.wValidBitsPerSample = 0;
+                this.dwChannelMask = 0;
+                this.SubFormat = Guid.Empty;
+            }
+            else
+            {
+                this.wFormatTag = unchecked((short)WAVE_FORMAT_EXTENSIBLE);
+                this.cbSize = 22;
+                this.wValidBitsPerSample = this.wBitsPerSample;
+                this.nBlockAlign = (short)((this.wBitsPerSample / 8) * this.nChannels);
+                this.dwChannelMask = (int)pcm.ChannelMask;
+                this.SubFormat = MediaSubType.PCM;
+            }
+            this.nAvgBytesPerSec = this.nSamplesPerSec * this.nBlockAlign;
+        }
+
+        public static WaveFormatExtensible FromMediaType(AMMediaType pMediaType)
+        {
+            if (MediaType.Audio != pMediaType.majorType)
+                throw new Exception("not Audio");
+            if (FormatType.WaveEx != pMediaType.formatType || pMediaType.formatSize < 18)
+                throw new Exception("not WaveEx");
+            WaveFormatEx pWfx = new WaveFormatEx();
+            Marshal.PtrToStructure(pMediaType.formatPtr, pWfx);
+            if (pWfx.wFormatTag == unchecked((short)WAVE_FORMAT_EXTENSIBLE) && pWfx.cbSize >= 22)
+            {
+                var pWfe = new WaveFormatExtensible();
+                Marshal.PtrToStructure(pMediaType.formatPtr, pWfe);
+                return pWfe;
+            }
+            return new WaveFormatExtensible() {
+                nChannels = pWfx.nChannels, 
+                nSamplesPerSec = pWfx.nSamplesPerSec, 
+                nBlockAlign = pWfx.nBlockAlign, 
+                wBitsPerSample = pWfx.wBitsPerSample, 
+                nAvgBytesPerSec = pWfx.nAvgBytesPerSec, 
+                wFormatTag = pWfx.wFormatTag, 
+                cbSize = 0
+            };
+        }
+        
+        public AudioPCMConfig GetConfig()
+        {
+            return new AudioPCMConfig(
+                wBitsPerSample,
+                nChannels,
+                nSamplesPerSec,
+                (AudioPCMConfig.SpeakerConfig)(wFormatTag == unchecked((short)WAVE_FORMAT_EXTENSIBLE) && cbSize >= 22 ? dwChannelMask : 0));
+        }
+
+        public short wFormatTag;        /* format type */
+        public short nChannels;         /* number of channels (i.e. mono, stereo, etc.) */
+        public int nSamplesPerSec;    /* sample rate */
+        public int nAvgBytesPerSec;   /* for buffer estimation */
+        public short nBlockAlign;       /* block size of data */
+        public short wBitsPerSample;
+        public short cbSize;
+        public short wValidBitsPerSample;
+        public int dwChannelMask;
+        public Guid SubFormat;
+    }
+}