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rewrite find_frame_end()

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new code correctly splits long start codes, also its about twice as fast

Originally committed as revision 8120 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2007-02-25 02:38:08 +00:00
parent 0b2d5a8ed5
commit 0268a54a65
1 changed files with 39 additions and 26 deletions
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65
libavcodec/h264.c
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@ -7990,36 +7990,45 @@ static int find_frame_end(H264Context *h, const uint8_t *buf, int buf_size){
//printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);
// mb_addr= pc->mb_addr - 1;
state= pc->state;
for(i=0; i<=buf_size; i++){
if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
tprintf("find_frame_end new startcode = %08x, frame_start_found = %d, pos = %d\n", state, pc->frame_start_found, i);
if(pc->frame_start_found){
// If there isn't one more byte in the buffer
// the test on first_mb_in_slice cannot be done yet
// do it at next call.
if (i >= buf_size) break;
if (buf[i] & 0x80) {
// first_mb_in_slice is 0, probably the first nal of a new
// slice
tprintf("find_frame_end frame_end_found, state = %08x, pos = %d\n", state, i);
pc->state=-1;
pc->frame_start_found= 0;
return i-4;
if(state>13)
state= 7;
for(i=0; i<buf_size; i++){
if(state==7){
for(; i<buf_size; i++){
if(!buf[i]){
state=2;
break;
}
}
pc->frame_start_found = 1;
}else if(state<=2){
if(buf[i]==1) state^= 5; //2->7, 1->4, 0->5
else if(buf[i]) state = 7;
else state>>=1; //2->1, 1->0, 0->0
}else if(state<=5){
int v= buf[i] & 0x1F;
if(v==7 || v==8 || v==9){
if(pc->frame_start_found){
i++;
found:
pc->state=7;
pc->frame_start_found= 0;
return i-(state&5);
}
}else if(v==1 || v==2 || v==5){
if(pc->frame_start_found){
state+=8;
continue;
}else
pc->frame_start_found = 1;
}
state= 7;
}else{
if(buf[i] & 0x80)
goto found;
state= 7;
}
if((state&0xFFFFFF1F) == 0x107 || (state&0xFFFFFF1F) == 0x108 || (state&0xFFFFFF1F) == 0x109){
if(pc->frame_start_found){
pc->state=-1;
pc->frame_start_found= 0;
return i-4;
}
}
if (i<buf_size)
state= (state<<8) | buf[i];
}
pc->state= state;
return END_NOT_FOUND;
}
@ -8042,6 +8051,10 @@ static int h264_parse(AVCodecParserContext *s,
return buf_size;
}
if(next<0){
find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
}
*poutbuf = (uint8_t *)buf;
*poutbuf_size = buf_size;
return next;