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scanAnnexB speed optimize

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Thulinma 2017-07-27 15:18:50 +02:00
parent 9be07e5ecb
commit cba764d8eb
1 changed files with 17 additions and 14 deletions
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27
lib/nal.cpp
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@ -79,21 +79,24 @@ namespace nalu {
///Scan data for Annex B start code. Returns pointer to it when found, null otherwise. ///Scan data for Annex B start code. Returns pointer to it when found, null otherwise.
const char * scanAnnexB(const char * data, uint32_t dataSize){ const char * scanAnnexB(const char * data, uint32_t dataSize){
int offset = 0; char * offset = (char*)data;
while(offset+2 < dataSize){ const char * maxData = data + dataSize - 2;
const char * begin = data + offset; while(offset < maxData){
bool t = (begin[2] == 1 && !begin[0] && !begin[1]); if (offset[2] > 1){
if(!t){ //We have no zero in the third byte, so we need to skip at least 3 bytes forward
if (begin[2]){//skip three bytes if the last one isn't zero
offset += 3; offset += 3;
}else if (begin[1]){//skip two bytes if the second one isn't zero continue;
offset +=2;
}else{//All other cases, skip one byte
offset++;
} }
}else{ if (!offset[2]){
return begin; //We skip forward 1 or 2 bytes depending on contents of the second byte
offset += (offset[1]?2:1);
continue;
} }
if (!offset[0] && !offset[1]){
return offset;
}
//We have no zero in the third byte, so we need to skip at least 3 bytes forward
offset += 3;
} }
return 0; return 0;
} }