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improve mpeg1/2-es detection 

Originally committed as revision 4923 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2006-02-02 13:56:42 +00:00
parent e2a5fd2049
commit 93d3e278cd
1 changed files with 17 additions and 20 deletions
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37
libavformat/raw.c
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@ -286,31 +286,28 @@ static int video_read_header(AVFormatContext *s,
#define SEQ_START_CODE 0x000001b3
#define GOP_START_CODE 0x000001b8
#define PICTURE_START_CODE 0x00000100
#define SLICE_START_CODE 0x00000101
#define PACK_START_CODE 0x000001ba
/* XXX: improve that by looking at several start codes */
static int mpegvideo_probe(AVProbeData *p)
{
int code;
const uint8_t *d;
uint32_t code= -1;
int pic=0, seq=0, slice=0, pspack=0;
int i;
/* we search the first start code. If it is a sequence, gop or
picture start code then we decide it is an mpeg video
stream. We do not send highest value to give a chance to mpegts */
/* NOTE: the search range was restricted to avoid too many false
detections */
if (p->buf_size < 6)
return 0;
d = p->buf;
code = (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | (d[3]);
if ((code & 0xffffff00) == 0x100) {
if (code == SEQ_START_CODE ||
code == GOP_START_CODE ||
code == PICTURE_START_CODE)
return 50 - 1;
else
return 0;
for(i=0; i<p->buf_size; i++){
code = (code<<8) + p->buf[i];
if ((code & 0xffffff00) == 0x100) {
switch(code){
case SEQ_START_CODE: seq++; break;
case PICTURE_START_CODE: pic++; break;
case SLICE_START_CODE: slice++; break;
case PACK_START_CODE: pspack++; break;
}
}
}
if(seq && pic && slice && seq<pic && (ABS(pic-slice)-1)*10 < pic && !pspack)
return AVPROBE_SCORE_MAX/2+1; // +1 for .mpg
return 0;
}