diff options
| author | Michael Niedermayer <michaelni@gmx.at> | 2013-11-09 00:30:27 +0100 |
|---|---|---|
| committer | Michael Niedermayer <michaelni@gmx.at> | 2013-11-09 00:45:35 +0100 |
| commit | 891f33cc705240907b58c88d0b119c4fad479d90 (patch) | |
| tree | 8204696dd692f6d2c30857bf7684ec99b0b723d1 | |
| parent | c79c7ffc9da7b954709fcccdcaea1abb27132691 (diff) | |
| download | ffmpeg-891f33cc705240907b58c88d0b119c4fad479d90.tar.gz | |
avformat/h261dec: optimize probe
about 3 times faster
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
| -rw-r--r-- | libavformat/h261dec.c | 37 |
1 files changed, 17 insertions, 20 deletions
diff --git a/libavformat/h261dec.c b/libavformat/h261dec.c index 8d882aec61..0bfc824226 100644 --- a/libavformat/h261dec.c +++ b/libavformat/h261dec.c @@ -25,33 +25,30 @@ static int h261_probe(AVProbeData *p) { - uint32_t code= -1; int i; int valid_psc=0; int invalid_psc=0; int next_gn=0; int src_fmt=0; - GetBitContext gb; - init_get_bits8(&gb, p->buf, p->buf_size); + for(i=0; i<p->buf_size; i++){ + if ((AV_RB16(&p->buf[i]) - 1) < 0xFFU) { + int shift = av_log2_16bit(p->buf[i+1]); + uint32_t code = AV_RB64(&p->buf[FFMAX(i-1, 0)]) >> (24+shift); + if ((code & 0xffff0000) == 0x10000) { + int gn= (code>>12)&0xf; + if(!gn) + src_fmt= code&8; + if(gn != next_gn) invalid_psc++; + else valid_psc++; - for(i=0; i<p->buf_size*8; i++){ - if ((code & 0x01ff0000) || !(code & 0xff00)) { - code = (code<<8) + get_bits(&gb, 8); - i += 7; - } else - code = (code<<1) + get_bits1(&gb); - if ((code & 0xffff0000) == 0x10000) { - int gn= (code>>12)&0xf; - if(!gn) - src_fmt= code&8; - if(gn != next_gn) invalid_psc++; - else valid_psc++; - - if(src_fmt){ // CIF - next_gn= (gn+1 )%13; - }else{ //QCIF - next_gn= (gn+1+!!gn)% 7; + if(src_fmt){ // CIF + static const int lut[16]={1,2,3,4,5,6,7,8,9,10,11,12,0,1,2,3}; + next_gn = lut[gn]; + }else{ //QCIF + static const int lut[16]={1,3,4,5,6,0,1,2,3,4,5,6,0,1,2,3,4}; + next_gn = lut[gn]; + } } } } |