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h261dec, ituh263dec: Avoid unnecessary -1 inside inner loop.

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3646 -> 3597 decicycles in inner loop when decoding
vsynth1-flv.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
This commit is contained in:
Reimar Döffinger 2014-08-31 20:30:04 +02:00
parent 8d6ec61186
commit 2a00812d82
2 changed files with 9 additions and 7 deletions
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7
libavcodec/h261dec.c
View File

@ -305,6 +305,7 @@ static int h261_decode_block(H261Context *h, int16_t *block, int n, int coded)
}
{
OPEN_READER(re, &s->gb);
i--; // offset by -1 to allow direct indexing of scan_table
for (;;) {
UPDATE_CACHE(re, &s->gb);
GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TCOEFF_VLC_BITS, 2, 0);
@ -330,17 +331,17 @@ static int h261_decode_block(H261Context *h, int16_t *block, int n, int coded)
SKIP_COUNTER(re, &s->gb, 1);
}
i += run;
if (i > 64) {
if (i >= 64) {
av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n",
s->mb_x, s->mb_y);
return -1;
}
j = scan_table[i-1];
j = scan_table[i];
block[j] = level;
}
CLOSE_READER(re, &s->gb);
}
s->block_last_index[n] = i - 1;
s->block_last_index[n] = i;
return 0;
}

9
libavcodec/ituh263dec.c
View File

@ -481,6 +481,7 @@ static int h263_decode_block(MpegEncContext * s, int16_t * block,
retry:
{
OPEN_READER(re, &s->gb);
i--; // offset by -1 to allow direct indexing of scan_table
for(;;) {
UPDATE_CACHE(re, &s->gb);
GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
@ -529,9 +530,9 @@ retry:
SKIP_COUNTER(re, &s->gb, 1);
}
i += run;
if (i > 64){
// redo update without last flag
i = i - run + ((run-1)&63);
if (i >= 64){
// redo update without last flag, revert -1 offset
i = i - run + ((run-1)&63) + 1;
if (i < 64) {
// only last marker, no overrun
block[scan_table[i]] = level;
@ -549,7 +550,7 @@ retry:
av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d i:%d\n", s->mb_x, s->mb_y, s->mb_intra);
return -1;
}
j = scan_table[i-1];
j = scan_table[i];
block[j] = level;
}
CLOSE_READER(re, &s->gb);