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Minor speed optimization to m4a lookup table build up.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@29770 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Andree Buschmann 2011-04-23 20:43:47 +00:00
parent 69e1647d2d
commit 7d1de584fe
1 changed files with 19 additions and 12 deletions
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31
apps/codecs/libm4a/demux.c
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@ -429,14 +429,14 @@ static bool read_chunk_stsc(qtmovie_t *qtmovie, size_t chunk_len)
static bool read_chunk_stco(qtmovie_t *qtmovie, size_t chunk_len)
{
uint32_t i, k;
uint32_t i, k, old_i;
uint32_t numentries;
int32_t idx = 0;
int32_t frame;
int32_t offset;
int32_t old_first;
int32_t new_first;
int32_t old_frame;
uint32_t idx = 0;
uint32_t frame;
uint32_t offset;
uint32_t old_first;
uint32_t new_first;
uint32_t old_frame;
size_t size_remaining = chunk_len - 8;
/* version + flags */
@ -471,18 +471,25 @@ static bool read_chunk_stco(qtmovie_t *qtmovie, size_t chunk_len)
* table. This reduces the memory consumption by a factor of 2 or even
* more. */
i = 1;
old_i = 1;
frame = 0;
old_frame = qtmovie->res->sample_to_chunk[0].num_samples;
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;
for (k = 1; k < numentries; ++k)
{
for (; i < qtmovie->res->num_sample_to_chunks; ++i)
{
old_frame = qtmovie->res->sample_to_chunk[i-1].num_samples;
old_first = qtmovie->res->sample_to_chunk[i-1].first_chunk;
new_first = qtmovie->res->sample_to_chunk[i ].first_chunk;
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_i = i;
}
if (qtmovie->res->sample_to_chunk[i].first_chunk > k)
if (new_first > k)
break;
frame += (new_first - old_first) * old_frame;