From 3571f9c5fd34a55ccff25fdaac5306f2e055b74f Mon Sep 17 00:00:00 2001 From: Josh Coalson Date: Mon, 6 Nov 2006 16:48:33 +0000 Subject: [PATCH] new seek algorithm for native FLAC from Miroslav --- src/libFLAC/stream_decoder.c | 216 +++++++++++++---------------------- 1 file changed, 79 insertions(+), 137 deletions(-) diff --git a/src/libFLAC/stream_decoder.c b/src/libFLAC/stream_decoder.c index b2346e9c..9aca775b 100644 --- a/src/libFLAC/stream_decoder.c +++ b/src/libFLAC/stream_decoder.c @@ -2924,23 +2924,24 @@ void send_error_to_client_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecod FLAC__bool seek_to_absolute_sample_(FLAC__StreamDecoder *decoder, FLAC__uint64 stream_length, FLAC__uint64 target_sample) { - FLAC__uint64 first_frame_offset = decoder->private_->first_frame_offset, lower_bound, upper_bound; - FLAC__int64 pos = -1, last_pos = -1; - int i, lower_seek_point = -1, upper_seek_point = -1; + FLAC__uint64 first_frame_offset = decoder->private_->first_frame_offset, lower_bound, upper_bound, lower_bound_sample, upper_bound_sample, this_frame_sample; + FLAC__int64 pos = -1; + int i; unsigned approx_bytes_per_frame; - FLAC__uint64 last_frame_sample = FLAC__U64L(0xffffffffffffffff); - FLAC__bool needs_seek; + FLAC__bool needs_seek = true, first_seek = true; const FLAC__uint64 total_samples = FLAC__stream_decoder_get_total_samples(decoder); const unsigned min_blocksize = decoder->private_->stream_info.data.stream_info.min_blocksize; const unsigned max_blocksize = decoder->private_->stream_info.data.stream_info.max_blocksize; const unsigned max_framesize = decoder->private_->stream_info.data.stream_info.max_framesize; + const unsigned min_framesize = decoder->private_->stream_info.data.stream_info.min_framesize; + /* take these from the current frame in case they've changed mid-stream */ const unsigned channels = FLAC__stream_decoder_get_channels(decoder); const unsigned bps = FLAC__stream_decoder_get_bits_per_sample(decoder); const FLAC__StreamMetadata_SeekTable *seek_table = decoder->private_->has_seek_table? &decoder->private_->seek_table.data.seek_table : 0; - /* we are just guessing here, but we want to guess high, not low */ + /* we are just guessing here */ if(max_framesize > 0) - approx_bytes_per_frame = max_framesize; + approx_bytes_per_frame = (max_framesize + min_framesize) / 2 + 1; /* * Check if it's a known fixed-blocksize stream. Note that though @@ -2959,15 +2960,12 @@ FLAC__bool seek_to_absolute_sample_(FLAC__StreamDecoder *decoder, FLAC__uint64 s * First, we set an upper and lower bound on where in the * stream we will search. For now we assume the worst case * scenario, which is our best guess at the beginning of - * the first and last frames. + * the first frame and end of the stream. */ lower_bound = first_frame_offset; - - /* calc the upper_bound, beyond which we never want to seek */ - if(max_framesize > 0) - upper_bound = stream_length - (max_framesize + 128 + 2); /* 128 for a possible ID3V1 tag, 2 for indexing differences */ - else - upper_bound = stream_length - ((channels * bps * FLAC__MAX_BLOCK_SIZE) / 8 + 128 + 2); + lower_bound_sample = 0; + upper_bound = stream_length; + upper_bound_sample = total_samples > 0 ? total_samples : target_sample; /* * Now we refine the bounds if we have a seektable with @@ -2982,7 +2980,7 @@ FLAC__bool seek_to_absolute_sample_(FLAC__StreamDecoder *decoder, FLAC__uint64 s } if(i >= 0) { /* i.e. we found a suitable seek point... */ lower_bound = first_frame_offset + seek_table->points[i].stream_offset; - lower_seek_point = i; + lower_bound_sample = seek_table->points[i].sample_number; } /* find the closest seek point > target_sample, if it exists */ @@ -2992,98 +2990,36 @@ FLAC__bool seek_to_absolute_sample_(FLAC__StreamDecoder *decoder, FLAC__uint64 s } if(i < (int)seek_table->num_points) { /* i.e. we found a suitable seek point... */ upper_bound = first_frame_offset + seek_table->points[i].stream_offset; - upper_seek_point = i; + upper_bound_sample = seek_table->points[i].sample_number; } } - /* - * Now guess at where within those bounds our target - * sample will be. - */ - if(seek_table && lower_seek_point >= 0) { - /* first see if our sample is within a few frames of the lower seekpoint */ - if(seek_table->points[lower_seek_point].sample_number <= target_sample && target_sample < seek_table->points[lower_seek_point].sample_number + (seek_table->points[lower_seek_point].frame_samples * 4)) { - pos = (FLAC__int64)lower_bound; - } - else if(upper_seek_point >= 0) { - const FLAC__uint64 target_offset = target_sample - seek_table->points[lower_seek_point].sample_number; - const FLAC__uint64 range_samples = seek_table->points[upper_seek_point].sample_number - seek_table->points[lower_seek_point].sample_number; - const FLAC__uint64 range_bytes = (upper_bound>lower_bound? upper_bound - lower_bound - 1 : 0); -#ifndef FLAC__INTEGER_ONLY_LIBRARY -#if defined _MSC_VER || defined __MINGW32__ - /* with MSVC you have to spoon feed it the casting */ - pos = (FLAC__int64)lower_bound + (FLAC__int64)(((FLAC__double)(FLAC__int64)target_offset / (FLAC__double)(FLAC__int64)range_samples) * (FLAC__double)(FLAC__int64)(range_bytes-1)) - approx_bytes_per_frame; -#else - pos = (FLAC__int64)lower_bound + (FLAC__int64)(((FLAC__double)target_offset / (FLAC__double)range_samples) * (FLAC__double)range_bytes) - approx_bytes_per_frame; -#endif -#else - /* a little less accurate: */ - if (range_bytes <= 0xffffffff) - pos = (FLAC__int64)lower_bound + (FLAC__int64)((target_offset * range_bytes) / range_samples) - approx_bytes_per_frame; - else /* @@@ WATCHOUT, ~2TB limit */ - pos = (FLAC__int64)lower_bound + (FLAC__int64)(((target_offset>>8) * (range_bytes>>8)) / (range_samples>>16)) - approx_bytes_per_frame; -#endif - } - } - - /* - * If there's no seek table, we need to use the metadata (if we - * have it) and the filelength to estimate the position of the - * frame with the correct sample. - */ - if(pos < 0 && total_samples > 0) { - /* - * For max accuracy we should be using - * (stream_length-first_frame_offset-1) in the divisor, but the - * difference is trivial and (stream_length-first_frame_offset) - * has no chance of underflow. - */ -#ifndef FLAC__INTEGER_ONLY_LIBRARY -#if defined _MSC_VER || defined __MINGW32__ - /* with VC++ you have to spoon feed it the casting */ - pos = (FLAC__int64)first_frame_offset + (FLAC__int64)(((FLAC__double)(FLAC__int64)target_sample / (FLAC__double)(FLAC__int64)total_samples) * (FLAC__double)(FLAC__int64)(stream_length-first_frame_offset)) - approx_bytes_per_frame; -#else - pos = (FLAC__int64)first_frame_offset + (FLAC__int64)(((FLAC__double)target_sample / (FLAC__double)total_samples) * (FLAC__double)(stream_length-first_frame_offset)) - approx_bytes_per_frame; -#endif -#else - /* a little less accurate: */ - if (stream_length < 0xffffffff) - pos = (FLAC__int64)first_frame_offset + (FLAC__int64)((target_sample * (stream_length-first_frame_offset)) / total_samples) - approx_bytes_per_frame; - else /* @@@ WATCHOUT, ~2TB limit */ - pos = (FLAC__int64)first_frame_offset + (FLAC__int64)(((target_sample>>8) * ((stream_length-first_frame_offset)>>8)) / (total_samples>>16)) - approx_bytes_per_frame; -#endif - } - - /* - * If there's no seek table and total_samples is unknown, we - * don't even bother trying to figure out a target, we just use - * our current position. - */ - if(pos < 0) { - FLAC__uint64 upos; - if(decoder->private_->tell_callback(decoder, &upos, decoder->private_->client_data) != FLAC__STREAM_DECODER_TELL_STATUS_OK) { - decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR; - return false; - } - pos = (FLAC__int64)upos; - needs_seek = false; - } - else - needs_seek = true; - - /* clip the position to the bounds, lower bound takes precedence */ - if(pos >= (FLAC__int64)upper_bound) { - pos = (FLAC__int64)upper_bound-1; - needs_seek = true; - } - if(pos < (FLAC__int64)lower_bound) { - pos = (FLAC__int64)lower_bound; - needs_seek = true; - } - decoder->private_->target_sample = target_sample; while(1) { + /* check if the bounds are still ok */ + if (lower_bound_sample >= upper_bound_sample || lower_bound > upper_bound) { + decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR; + return false; + } if(needs_seek) { +#ifndef FLAC__INTEGER_ONLY_LIBRARY +#if defined _MSC_VER || defined __MINGW32__ + /* with VC++ you have to spoon feed it the casting */ + pos = (FLAC__int64)lower_bound + (FLAC__int64)((FLAC__double)(FLAC__int64)(target_sample - lower_bound_sample) / (FLAC__double)(FLAC__int64)(upper_bound_sample - lower_bound_sample) * (FLAC__double)(FLAC__int64)(upper_bound - lower_bound)) - approx_bytes_per_frame; +#else + pos = (FLAC__int64)lower_bound + (FLAC__int64)((FLAC__double)(target_sample - lower_bound_sample) / (FLAC__double)(upper_bound_sample - lower_bound_sample) * (FLAC__double)(upper_bound - lower_bound)) - approx_bytes_per_frame; +#endif +#else + /* a little less accurate: */ + if (upper_bound - lower_bound < 0xffffffff) + pos = (FLAC__int64)lower_bound + (FLAC__int64)(((target_sample - lower_bound_sample) * (upper_bound - lower_bound)) / (upper_bound_sample - lower_bound_sample)) - approx_bytes_per_frame; + else /* @@@ WATCHOUT, ~2TB limit */ + pos = (FLAC__int64)lower_bound + (FLAC__int64)((((target_sample - lower_bound_sample)>>8) * ((upper_bound - lower_bound)>>8)) / ((upper_bound_sample - lower_bound_sample)>>16)) - approx_bytes_per_frame; +#endif + if(pos >= (FLAC__int64)upper_bound) + pos = (FLAC__int64)upper_bound - 1; + if(pos < (FLAC__int64)lower_bound) + pos = (FLAC__int64)lower_bound; if(decoder->private_->seek_callback(decoder, (FLAC__uint64)pos, decoder->private_->client_data) != FLAC__STREAM_DECODER_SEEK_STATUS_OK) { decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR; return false; @@ -3114,44 +3050,50 @@ FLAC__bool seek_to_absolute_sample_(FLAC__StreamDecoder *decoder, FLAC__uint64 s if(!decoder->private_->is_seeking) { break; } - else { /* we need to narrow the search */ - const FLAC__uint64 this_frame_sample = decoder->private_->last_frame.header.number.sample_number; - FLAC__ASSERT(decoder->private_->last_frame.header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER); - if(this_frame_sample == last_frame_sample && pos < last_pos) { - /* our last move backwards wasn't big enough, double it */ - pos -= (last_pos - pos); - needs_seek = true; + this_frame_sample = decoder->private_->last_frame.header.number.sample_number; + + if (!decoder->private_->samples_decoded || (this_frame_sample + decoder->private_->last_frame.header.blocksize >= upper_bound_sample && !first_seek)) { + if (pos == (FLAC__int64)lower_bound || !needs_seek) { + decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR; + return false; } - else { - if(target_sample < this_frame_sample) { - last_pos = pos; - approx_bytes_per_frame = decoder->private_->last_frame.header.blocksize * channels * bps/8 + 64; - pos -= approx_bytes_per_frame; - needs_seek = true; - } - else { /* target_sample >= this_frame_sample + this frame's blocksize */ - FLAC__uint64 upos; - if(decoder->private_->tell_callback(decoder, &upos, decoder->private_->client_data) != FLAC__STREAM_DECODER_TELL_STATUS_OK) { - decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR; - return false; - } - last_pos = pos; - pos = (FLAC__int64)upos; - pos -= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder); - needs_seek = false; - /* - * if we haven't hit the target frame yet and our position hasn't changed, - * it means we're at the end of the stream and the seek target does not exist. - */ - if(last_pos == pos) { - decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR; - return false; - } - } + /* our last move backwards wasn't big enough, try again */ + approx_bytes_per_frame *= 2; + continue; + } + /* allow one seek over upper bound, required for streams with unknown total_samples */ + first_seek = false; + + /* make sure we are not seeking in corrupted stream */ + if (this_frame_sample < lower_bound_sample) { + decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR; + return false; + } + + FLAC__ASSERT(decoder->private_->last_frame.header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER); + + approx_bytes_per_frame = decoder->private_->last_frame.header.blocksize * channels * bps/8 + 64; + + /* we need to narrow the search */ + if(target_sample < this_frame_sample) { + upper_bound_sample = this_frame_sample + decoder->private_->last_frame.header.blocksize; + if(!FLAC__stream_decoder_get_decode_position(decoder, &upper_bound)) { + decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR; + return false; + } + } + else { + /* target_sample >= this_frame_sample + this frame's blocksize */ + + /* we are close, continue in decoding next frames */ + if(target_sample < this_frame_sample + 4 * decoder->private_->last_frame.header.blocksize) + needs_seek = false; + + lower_bound_sample = this_frame_sample + decoder->private_->last_frame.header.blocksize; + if(!FLAC__stream_decoder_get_decode_position(decoder, &lower_bound)) { + decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR; + return false; } - if(pos < (FLAC__int64)lower_bound) - pos = (FLAC__int64)lower_bound; - last_frame_sample = this_frame_sample; } }