如何在FFmpeg中尋找C/C++

Question

有誰知道如何在FFmpeg中實現以秒（或毫秒）爲單位的搜尋。我目前使用av_read_frame（）有一個循環遍歷視頻幀，我想確定這個幀應該在幾秒鐘內到達的時間。如果它達到某個點，那麼我想在視頻中尋找一個稍後的點。順便說它不是視頻播放器，只是處理幀。我聽說我應該能夠從數據包中獲得dts或pts，但其始終返回0.

Answer 1

注意：這是過時的，它應該仍然有效，但現在有av_seek_frame()正式執行它。

我沒有寫這一點，但這裏是從樣品我

bool seekMs(int tsms) 
{ 
    //printf("**** SEEK TO ms %d. LLT: %d. LT: %d. LLF: %d. LF: %d. LastFrameOk: %d\n",tsms,LastLastFrameTime,LastFrameTime,LastLastFrameNumber,LastFrameNumber,(int)LastFrameOk); 

    // Convert time into frame number 
    DesiredFrameNumber = ffmpeg::av_rescale(tsms,pFormatCtx->streams[videoStream]->time_base.den,pFormatCtx->streams[videoStream]->time_base.num); 
    DesiredFrameNumber/=1000; 

    return seekFrame(DesiredFrameNumber); 
} 

bool seekFrame(ffmpeg::int64_t frame) 
{ 

    //printf("**** seekFrame to %d. LLT: %d. LT: %d. LLF: %d. LF: %d. LastFrameOk: %d\n",(int)frame,LastLastFrameTime,LastFrameTime,LastLastFrameNumber,LastFrameNumber,(int)LastFrameOk); 

    // Seek if: 
    // - we don't know where we are (Ok=false) 
    // - we know where we are but: 
    // - the desired frame is after the last decoded frame (this could be optimized: if the distance is small, calling decodeSeekFrame may be faster than seeking from the last key frame) 
    // - the desired frame is smaller or equal than the previous to the last decoded frame. Equal because if frame==LastLastFrameNumber we don't want the LastFrame, but the one before->we need to seek there 
    if((LastFrameOk==false) || ((LastFrameOk==true) && (frame<=LastLastFrameNumber || frame>LastFrameNumber))) 
    { 
     //printf("\t avformat_seek_file\n"); 
     if(ffmpeg::avformat_seek_file(pFormatCtx,videoStream,0,frame,frame,AVSEEK_FLAG_FRAME)<0) 
     return false; 

     avcodec_flush_buffers(pCodecCtx); 

     DesiredFrameNumber = frame; 
     LastFrameOk=false; 
    } 
    //printf("\t decodeSeekFrame\n"); 

    return decodeSeekFrame(frame); 

    return true; 
}