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Codecs: mp4: Improve support for long files. Part 2

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Don't store sample_to_chunk table and read data on demand instead (it's required only once for building lookup table). It allows to store 2x bigger lookup table.

Change-Id: Ida79d0c281040300d6561e124fe10ebacb0e4679
This commit is contained in:
roman.artiukhin 2023-08-31 00:45:46 +03:00 • committed by Solomon Peachy
parent 3c9be11411
commit 6acb6446e6
2 changed files with 38 additions and 42 deletions
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78
lib/rbcodec/codecs/libm4a/demux.c
View file

@ -29,6 +29,8 @@
*
*/
//#define DEBUG
#include <string.h>
#include <inttypes.h>
#include <stdlib.h>
@ -411,7 +413,6 @@ static bool read_chunk_stsz(qtmovie_t *qtmovie, size_t chunk_len)
static bool read_chunk_stsc(qtmovie_t *qtmovie, size_t chunk_len)
{
unsigned int i;
uint32_t numentries;
size_t size_remaining = chunk_len - 8;
@ -423,43 +424,29 @@ static bool read_chunk_stsc(qtmovie_t *qtmovie, size_t chunk_len)
size_remaining -= 4;
qtmovie->res->num_sample_to_chunks = numentries;
qtmovie->res->sample_to_chunk = malloc(numentries * sizeof(sample_to_chunk_t));
if (!qtmovie->res->sample_to_chunk)
{
DEBUGF("stsc too large\n");
return false;
}
for (i = 0; i < numentries; i++)
{
qtmovie->res->sample_to_chunk[i].first_chunk =
stream_read_uint32(qtmovie->stream);
qtmovie->res->sample_to_chunk[i].num_samples =
stream_read_uint32(qtmovie->stream);
stream_read_uint32(qtmovie->stream);
size_remaining -= 12;
}
qtmovie->res->sample_to_chunk_offset = stream_tell(qtmovie->stream);
if (size_remaining)
{
DEBUGF("ehm, size remianing?\n");
stream_skip(qtmovie->stream, size_remaining);
}
return true;
}
static void stream_read_sample_to_chunk(stream_t *stream, uint32_t *first_chunk, uint32_t *num_samples)
{
(*first_chunk) = stream_read_uint32(stream);
(*num_samples) = stream_read_uint32(stream);
stream_skip(stream, 4);
}
static bool read_chunk_stco(qtmovie_t *qtmovie, size_t chunk_len)
{
uint32_t i, k, old_i;
uint32_t numentries;
uint32_t idx = 0;
uint32_t frame;
uint32_t offset;
uint32_t old_first;
uint32_t new_first;
uint32_t old_frame;
uint32_t old_first, new_first;
uint32_t old_frame, new_frame;
size_t size_remaining = chunk_len - 8;
/* version + flags */
@ -494,10 +481,6 @@ static bool read_chunk_stco(qtmovie_t *qtmovie, size_t chunk_len)
return false;
}
/* read first offset */
offset = stream_read_uint32(qtmovie->stream);
size_remaining -= 4;
/* Build up lookup table. The lookup table contains the sample index and
* byte position in the file for each chunk. This table is used to seek
* and resume (see m4a_seek() and m4a_seek_raw() in libm4a/m4a.c) and
@ -509,12 +492,29 @@ static bool read_chunk_stco(qtmovie_t *qtmovie, size_t chunk_len)
* accepted to be able to avoid allocation of the large sample_byte_size[]
* table. This reduces the memory consumption by a factor of 2 or even
* more. */
uint32_t idx = 0;
for (i = 0; i < numentries; ++i)
{
if (i % accuracy_divider == 0)
{
qtmovie->res->lookup_table[idx++].offset = stream_read_uint32(qtmovie->stream);
}
else
{
stream_skip(qtmovie->stream, 4);
}
size_remaining -= 4;
}
idx = 0;
i = 1;
old_i = 1;
frame = 0;
old_first = qtmovie->res->sample_to_chunk[0].first_chunk;
old_frame = qtmovie->res->sample_to_chunk[0].num_samples;
new_first = qtmovie->res->sample_to_chunk[1].first_chunk;
int32_t current_offset = stream_tell(qtmovie->stream);
stream_seek(qtmovie->stream, qtmovie->res->sample_to_chunk_offset);
stream_read_sample_to_chunk(qtmovie->stream, &old_first, &old_frame);
stream_read_sample_to_chunk(qtmovie->stream, &new_first, &new_frame);
for (k = 1; k < numentries; ++k)
{
for (; i < qtmovie->res->num_sample_to_chunks; ++i)
@ -522,9 +522,9 @@ static bool read_chunk_stco(qtmovie_t *qtmovie, size_t chunk_len)
if (i > old_i)
{
/* Only access sample_to_chunk[] if new data is required. */
old_first = qtmovie->res->sample_to_chunk[i-1].first_chunk;
old_frame = qtmovie->res->sample_to_chunk[i-1].num_samples;
new_first = qtmovie->res->sample_to_chunk[i ].first_chunk;
old_first = new_first;
old_frame = new_frame;
stream_read_sample_to_chunk(qtmovie->stream, &new_first, &new_frame);
old_i = i;
}
@ -537,20 +537,16 @@ static bool read_chunk_stco(qtmovie_t *qtmovie, size_t chunk_len)
if ((k-1) % accuracy_divider == 0)
{
qtmovie->res->lookup_table[idx].sample = frame;
qtmovie->res->lookup_table[idx].offset = offset;
idx++;
qtmovie->res->lookup_table[idx++].sample = frame;
}
frame -= (k - old_first) * old_frame;
offset = stream_read_uint32(qtmovie->stream);
size_remaining -= 4;
}
/* zero-terminate the lookup table */
qtmovie->res->lookup_table[idx].sample = 0;
qtmovie->res->lookup_table[idx].offset = 0;
stream_seek(qtmovie->stream, current_offset);
if (size_remaining)
{
DEBUGF("ehm, size remianing?\n");

2
lib/rbcodec/codecs/libm4a/m4a.h
View file

@ -71,7 +71,7 @@ typedef struct
fourcc_t format;
void *buf;
sample_to_chunk_t *sample_to_chunk;
int32_t sample_to_chunk_offset;
uint32_t num_sample_to_chunks;
sample_offset_t *lookup_table;