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Codecs: mp4: Accurate seek in large files with small lookup_table

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Read sample_byte_sizes table on demand when it can't be cached

Change-Id: I2191be63ceebfd8b16e1e973e13c5b51986b6564
This commit is contained in:
roman.artiukhin 2023-09-05 00:45:32 +03:00
parent e01055a287
commit 57409f52d5
3 changed files with 25 additions and 6 deletions
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11
lib/rbcodec/codecs/libm4a/demux.c
View file

@ -400,7 +400,8 @@ static bool read_chunk_stsz(qtmovie_t *qtmovie, size_t chunk_len)
} }
else else
{ {
DEBUGF("stsz too large, ignoring it\n"); qtmovie->res->sample_byte_sizes_offset = stream_tell(qtmovie->stream);
DEBUGF("stsz too large: %u, save sample_byte_sizes_offset\n", numsizes);
} }
if (size_remaining) if (size_remaining)
@ -481,6 +482,14 @@ static bool read_chunk_stco(qtmovie_t *qtmovie, size_t chunk_len)
return false; return false;
} }
// Reading sample_byte_sizes data on seek can lead to additional re-buffering.
// So skip it if we have good enough seek accuracy via lookup_table (3000 ms)
if (qtmovie->res->sample_byte_sizes_offset && ci->id3->length / fit_numentries <= 3000)
{
qtmovie->res->sample_byte_sizes_offset = 0;
DEBUGF("lookup_table seek accuracy %ld ms, ignoring sample_byte_sizes_offset \n", ci->id3->length / fit_numentries);
}
/* Build up lookup table. The lookup table contains the sample index and /* 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 * 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 * and resume (see m4a_seek() and m4a_seek_raw() in libm4a/m4a.c) and

19
lib/rbcodec/codecs/libm4a/m4a.c
View file

@ -211,11 +211,13 @@ unsigned int m4a_seek(demux_res_t* demux_res, stream_t* stream,
sound_sample_i += time_cnt * time_dur; sound_sample_i += time_cnt * time_dur;
} }
DEBUGF("seek chunk=%lu, sample=%lu, soundsample=%lu, offset=%lu\n", if (demux_res->sample_byte_sizes_offset)
(unsigned long)chunk, (unsigned long)chunk_first_sample, {
sound_sample_i, (unsigned long)offset); stream->ci->seek_buffer(demux_res->sample_byte_sizes_offset + chunk_first_sample * 4);
}
if (tsz_tab) { if (tsz_tab || demux_res->sample_byte_sizes_offset)
{
/* We have a sample-to-bytes table available so we can do accurate /* We have a sample-to-bytes table available so we can do accurate
* seeking. Move one sample at a time and update the file offset and * seeking. Move one sample at a time and update the file offset and
* PCM sample offset as we go. */ * PCM sample offset as we go. */
@ -229,7 +231,7 @@ unsigned int m4a_seek(demux_res_t* demux_res, stream_t* stream,
time_dur = tts_tab[time].sample_duration; time_dur = tts_tab[time].sample_duration;
} }
offset += tsz_tab[i]; offset += tsz_tab ? tsz_tab[i] : stream_read_uint32(stream);
sound_sample_i += time_dur; sound_sample_i += time_dur;
time_cnt--; time_cnt--;
} }
@ -239,6 +241,13 @@ unsigned int m4a_seek(demux_res_t* demux_res, stream_t* stream,
sample_i = chunk_first_sample; sample_i = chunk_first_sample;
} }
DEBUGF("seek chunk=%lu, chunk_first_sample=%lu, sample_i=%u, soundsample=%lu, offset=%lu\n",
(unsigned long)chunk,
(unsigned long)chunk_first_sample,
sample_i,
(unsigned long)sound_sample_i,
(unsigned long)offset);
if (stream->ci->seek_buffer(offset)) if (stream->ci->seek_buffer(offset))
{ {
*sound_samples_done = sound_sample_i; *sound_samples_done = sound_sample_i;

1
lib/rbcodec/codecs/libm4a/m4a.h
View file

@ -82,6 +82,7 @@ typedef struct
uint32_t *sample_byte_sizes; uint32_t *sample_byte_sizes;
uint32_t num_sample_byte_sizes; uint32_t num_sample_byte_sizes;
int32_t sample_byte_sizes_offset;
uint32_t codecdata_len; uint32_t codecdata_len;
uint8_t codecdata[MAX_CODECDATA_SIZE]; uint8_t codecdata[MAX_CODECDATA_SIZE];