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• I have created a commandlist but when I run ffmpeg() it says not defined. Does the ffmpeg() needs the commandlist nested or am I missing something ?

  5 septembre 2022, par jiraiya_sensei

  #/ I have ommited the first half of the code/

  


  def buildFFmpeg():
        commandlist = [
            "ffmpeg",
            "-i",
            inputdic[1],
            "-c:v",
            inputdic[4],
            "-preset",
            inputdic[3],
            "-crf",
            inputdic[2],
            "-q:v",
            inputdic[6],
            "-c:a",
            inputdic[5],
            "-b:a",
            inputdic[7],
            "output.mkv"        
            ]
    
    return commandlist
    
    def runFFmpeg(commandlist):

            print(commandlist)               

            if subprocess.run(commandlist).returncode == 0:

                    print ("FFmpeg Script Ran Successfully")

            else:
                    print ("There was an error running your FFmpeg script")
                    
                
    print('Press 1 to start to encoding or 2 to stop this process')

    start = input('Press to start: ')

    x = int(start)

    if x == 1:
        runFFmpeg(buildFFmpeg())

    else:
         exit()


  


  so with the changes of runFFmpeg() — runFFmpeg(buildFFmpeg()) in line 58 and def runFFmpeg() : — def runFFmpeg(commandlist) : in line45 the code runs successfully. But I would like to understand as to how defining the def runFFmpeg(commandlist) : and executing runFFmpeg(buildFFmpeg()) makes the code work.

  


• aarch64 : vp9itxfm : Reorder iadst16 coeffs

  31 décembre 2016, par Martin Storsjö

  aarch64 : vp9itxfm : Reorder iadst16 coeffs
  This matches the order they are in the 16 bpp version.
  There they are in this order, to make sure we access them in the
  
  same order they are declared, easing loading only half of the
  
  coefficients at a time.
  This makes the 8 bpp version match the 16 bpp version better.
  This is cherrypicked from libav commit
  
  b8f66c0838b4c645227f23a35b4d54373da4c60a.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavcodec/aarch64/vp9itxfm_neon.S

• How to write a video stream containing B-frame and no DTS to a MP4 container ?

  14 février 2020, par SteveH

  I want to save a h264 video stream received from a RTSP source to a MP4 container.
  Not like other questions asked on SO, here the challenges I face are :

  • The stream contains B frames.

  • The stream has only PTS given by the RTP/RTCP.

  Here is the code I did

  //  ffmpeg
  
      pkt->data = ..;
  
      pkt->size = ..;
  
      pkt->flags = bKeyFrame? AV_PKT_FLAG_KEY : 0;    
  
      pkt->dts = AV_NOPTS_VALUE;
  
      pkt->pts = PTS;
  
  
  
      // PTS is based on epoch microseconds so I ignored re-scaling.
  
      //av_packet_rescale_ts(pkt, { 1, AV_TIME_BASE }, muxTimebase);
  
  
  
      auto ret = av_interleaved_write_frame(m_pAVFormatCtx, pkt);

  I received a lot of error messages like this :
  "Application provided invalid, non monotonically increasing dts to muxer ...".

  Result : the mp4 file is playable via VLC but the FPS is just a half of the original FPS and the video duration is incorrect (VLC shows a weird number).

  So how do I set correct DTS and PTS before sending to the container ?

  Update :
  I have tried some changes, though not successfully yet, I found that the reason of the frame rate drop is due to the muxer discards frames having incorrect DTS.
  Additionally, if I set start of PTS and DTS value too big, some players like VLC has to delay some time before showing video.