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#include "libavutil/intreadwrite.h" |
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#include "avformat.h" |
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#include "rawdec.h" |
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static int h261_probe(const AVProbeData *p) |
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{ |
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int i; |
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int valid_psc=0; |
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int invalid_psc=0; |
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int next_gn=0; |
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int src_fmt=0; |
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for(i=0; i<p->buf_size; i++){ |
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if ((AV_RB16(&p->buf[i]) - 1) < 0xFFU) { |
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int shift = av_log2_16bit(p->buf[i+1]); |
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uint32_t code = AV_RB64(&p->buf[FFMAX(i-1, 0)]) >> (24+shift); |
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if ((code & 0xffff0000) == 0x10000) { |
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int gn= (code>>12)&0xf; |
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if(!gn) |
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src_fmt= code&8; |
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if(gn != next_gn) invalid_psc++; |
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else valid_psc++; |
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if(src_fmt){ |
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static const int lut[16]={1,2,3,4,5,6,7,8,9,10,11,12,0,16,16,16}; |
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next_gn = lut[gn]; |
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}else{ |
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static const int lut[16]={1,3,16,5,16,0,16,16,16,16,16,16,16,16,16,16}; |
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next_gn = lut[gn]; |
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} |
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} |
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} |
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} |
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if(valid_psc > 2*invalid_psc + 6){ |
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return AVPROBE_SCORE_EXTENSION; |
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}else if(valid_psc > 2*invalid_psc + 2) |
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return AVPROBE_SCORE_EXTENSION / 2; |
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return 0; |
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} |
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FF_DEF_RAWVIDEO_DEMUXER(h261, "raw H.261", h261_probe, "h261", AV_CODEC_ID_H261) |
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