[Flac-dev] better seeking
Miroslav Lichvar
lichvarm at phoenix.inf.upol.cz
Fri Nov 3 01:01:42 PST 2006
On Mon, Oct 30, 2006 at 11:13:25AM -0800, Josh Coalson wrote:
> my apologies for not doing this before Miroslav... I will definitely
> integrate it this time.
Thanks. Sending latest version of the patch. Now it can seek in files
that have large id3 tag (or any random data) at the end and it won't loop on
streams with shuffled frames.
--
Miroslav Lichvar
-------------- next part --------------
Index: src/libFLAC/stream_decoder.c
===================================================================
RCS file: /cvsroot/flac/flac/src/libFLAC/stream_decoder.c,v
retrieving revision 1.117
diff -u -r1.117 stream_decoder.c
--- src/libFLAC/stream_decoder.c 16 Oct 2006 15:49:18 -0000 1.117
+++ src/libFLAC/stream_decoder.c 3 Nov 2006 08:32:35 -0000
@@ -2923,23 +2923,23 @@
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 channels = FLAC__stream_decoder_get_channels(decoder);
- const unsigned bps = FLAC__stream_decoder_get_bits_per_sample(decoder);
+ const unsigned min_framesize = decoder->private_->stream_info.data.stream_info.min_framesize;
+ const unsigned channels = decoder->private_->stream_info.data.stream_info.channels;
+ const unsigned bps = decoder->private_->stream_info.data.stream_info.bits_per_sample;
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
@@ -2958,15 +2958,12 @@
* 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
@@ -2981,7 +2978,7 @@
}
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 */
@@ -2991,98 +2988,36 @@
}
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;
}
}
+ decoder->private_->target_sample = target_sample;
- /*
- * 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);
+ while(1) {
+ /* check if the bounds are still ok */
+ if (lower_bound_sample + FLAC__MIN_BLOCK_SIZE > 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 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;
+ /* 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_offset / (FLAC__double)range_samples) * (FLAC__double)range_bytes) - approx_bytes_per_frame;
+ 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 (range_bytes <= 0xffffffff)
- pos = (FLAC__int64)lower_bound + (FLAC__int64)((target_offset * range_bytes) / range_samples) - approx_bytes_per_frame;
+ 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_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;
+ 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 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) {
- if(needs_seek) {
+ 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;
@@ -3113,44 +3048,50 @@
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;
}
}
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