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• How to compare/show the difference between 2 videos in ffmpeg ?

  25 janvier 2016, par polarka

  I am a newbie at encoding. I have read and tried x264 in lossless mode (-qp 0), however I’d like to make sure that in my new video, every single pixel contains the same information as the source file (which is in YUV 420 so the loss of color conversion is avoidable, as far as I know). I want to be able to check that, because I don’t believe in that if someone just says its lossless.

  I welcome answers suggesting other codecs for lossless encoding, my only requirements for codecs are having one of the best compression rate and let me to pick different calculation times (such as the range from placebo to veryfast in x264) in order to adjust the compression level and calc time to my needs. But keep in mind that the original question is about how can I calculate the differences frame by frame of two videos and export it to a 3rd file, so I can watch it myself. I think that knowledge (if its possible and doesnt have serious limitations) will be useful for me in the future too.

• Fix CBR output for IP multicasting video

  19 août 2014, par ddhung

  I’m using ffmpeg for transcoding live ip multicasting video on server linux Centos 5.9 OS. This is my ffmpeg command

  ffmpeg -i "udp:// x.x.x.x:6000?fifo_size=1000000&overrun_nonfatal=1&timeout=1000000" -filter:v yadif=0:-1:1 -vcodec libx264 -vprofile main -level 30 -tune zerolatency -pass 1 -b:v 900k -minrate 900k -maxrate 900k -bufsize 900k -x264opts nal_hrd=cbr:rc_lookahead=40:interlaced=1:scenecut=0:cabac=1:keyint=120:deblock=0,0:aud=1:qpmin=16:qpmax=51:qpstep=10:ref=2:mixed-refs=1:subme=9:me=esa:chroma_me=0:merange=64:8x8dct=0:fast_pskip=0:chroma_qp_offset=0:trellis=2:psy=0:bframes=0:weightp=2:sliced_threads -s:v 720x576 -r:v 25 -force_key_frames 'expr:gte(t,n_forced*3)' -threads 0 -acodec aac -strict -2 -ac 1 -ar 32000 -b:a 32k -filter:a volume=1 -f mpegts -muxrate 1400k udp://x.x.x.x:6000?pkt_size=1316

  My output video is for broadcasting so I have to configure CBR video output by feature –muxrate. But when I watch this stream on VLC the bitrate change very much not constant. The null packet is very high to force cbr mpeg2ts output.

  I also measure IP output video by HST3000 JDSU equipment and I see the measurement result is very bad as images.
  The PCR Jitter, IGMP Latency, Jitter Max which is not good as measurement standard by JDSU

  I try many way to change the ffmpeg command but not successful. The bitrate changes sometime > 1400kbps a lot. I think the problem may be the bitrate not constant. I have heard to change the muxrate output is CBR, it had to be change the code C mpegtsenc.c in libavformat library to new patch.
  So could you help me fix this problem and make the measurment result is better.
  Thank you so much.

  Best Regards

• Pipe a HTTP response

  30 juillet 2014, par viperfx

  How do I pipe an HTTP response like in NodeJS. Here is the snippet I am using in NodeJS :

  request({
  
    url: audio_file_url,
  
  }).pipe(ffmpeg_process.stdin);

  How can I achieve the same result in Go ?

  I am trying to pipe a audio stream from HTTP into an FFmpeg process so that it converts it on the fly and returns the converted file back to the client.

  Just so its clear to everyone here is my source code so far :

  func encodeAudio(w http.ResponseWriter, req *http.Request) {
  
      path, err := exec.LookPath("youtube-dl")
  
      if err != nil {
  
          log.Fatal("LookPath: ", err)
  
      }
  
      path_ff, err_ff := exec.LookPath("ffmpeg")
  
      if err != nil {
  
          log.Fatal("LookPath: ", err_ff)
  
      }
  
  
  
      streamLink := exec.Command(path,"-f", "140", "-g", "https://www.youtube.com/watch?v=VIDEOID")
  
  
  
      var out bytes.Buffer
  
      streamLink.Stdout = &out
  
      cmdFF := exec.Command(path_ff, "-i", "pipe:0", "-acodec", "libmp3lame", "-f", "mp3", "-")
  
      resp, err := http.Get(out.String())
  
      if err != nil {
  
          log.Fatal(err)
  
      }
  
      // pr, pw := io.Pipe()
  
      defer resp.Body.Close()
  
      cmdFF.Stdin = resp.Body
  
      cmdFF.Stdout = w
  
      streamLink.Run()
  
      //get ffmpeg running in another goroutine to receive data
  
      errCh := make(chan error, 1)
  
      go func() {
  
          errCh <- cmdFF.Run()
  
      }()
  
  
  
      // close the pipeline to signal the end of the stream
  
      // pw.Close()
  
      // pr.Close()
  
  
  
      // check for an error from ffmpeg
  
      if err := <-errCh; err != nil {
  
          // ff error
  
      }
  
  }

  Error : 2014/07/29 23:04:02 Get : unsupported protocol scheme ""