claunia/flac
1
0
Fork 0
mirror of https://github.com/claunia/flac.git synced 2025-12-16 18:54:26 +00:00
Code Issues Packages Projects Releases Wiki Activity

new seek algorithm for native FLAC from Miroslav

Browse Source
This commit is contained in:
Josh Coalson
2006-11-06 16:48:33 +00:00
parent b1c3798d77
commit 3571f9c5fd
1 changed files with 79 additions and 137 deletions
Download Patch File Download Diff File Expand all files Collapse all files

216
src/libFLAC/stream_decoder.c
View File

@@ -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;
}
}