How to seek in FFmpeg C/C++

NOTE: This is out of date, it should still work but there is now av_seek_frame() to do it officially.

I didn't write this but here is some code from a sample I have

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;}