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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
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@ -400,7 +400,8 @@ static bool read_chunk_stsz(qtmovie_t *qtmovie, size_t chunk_len)
}
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)
@ -481,6 +482,14 @@ static bool read_chunk_stco(qtmovie_t *qtmovie, size_t chunk_len)
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
* 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