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| author | Michael Niedermayer <michaelni@gmx.at> | 2014-01-26 02:53:17 +0100 |
|---|---|---|
| committer | Michael Niedermayer <michaelni@gmx.at> | 2014-01-26 02:57:29 +0100 |
| commit | 6a92598e149bcc2b5ec0a6c0cd940ef19b9ae86f (patch) | |
| tree | b6d0fe1021980895a531e67699a62c67ad7624d8 | |
| parent | 20626f53e9f41cb3db82329ed3db7d773cfa3a8f (diff) | |
| download | ffmpeg-6a92598e149bcc2b5ec0a6c0cd940ef19b9ae86f.tar.gz | |
avcodec/mpeg12dec: Redesign index checks for mpeg2_fast_decode_block_intra
This fixes the speed regression from 20626f53e9f41cb3db82329ed3db7d773cfa3a8f
and still checks sufficiently to prevent out of allocated memory accesses
due to the index
Before:
1681 decicycles in mpeg2_fast_decode_block_intra, 4194238 runs, 66 skips
After:
1658 decicycles in mpeg2_fast_decode_block_intra, 4194248 runs, 56 skips
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
| -rw-r--r-- | libavcodec/mpeg12dec.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c index 2d6bada76c..f1899e0f9f 100644 --- a/libavcodec/mpeg12dec.c +++ b/libavcodec/mpeg12dec.c @@ -628,11 +628,10 @@ static inline int mpeg2_fast_decode_block_intra(MpegEncContext *s, int16_t *bloc UPDATE_CACHE(re, &s->gb); GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0); - if (level >= 64) { + if (level >= 64 || i > 63) { break; } else if (level != 0) { i += run; - check_scantable_index(s, i); j = scantable[i]; level = (level * qscale * quant_matrix[j]) >> 4; level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1); @@ -643,7 +642,6 @@ static inline int mpeg2_fast_decode_block_intra(MpegEncContext *s, int16_t *bloc UPDATE_CACHE(re, &s->gb); level = SHOW_SBITS(re, &s->gb, 12); SKIP_BITS(re, &s->gb, 12); i += run; - check_scantable_index(s, i); j = scantable[i]; if (level < 0) { level = (-level * qscale * quant_matrix[j]) >> 4; |