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• How to retrieve FFMPEG (called from OpenCV) Python decoding error

  15 décembre 2020, par user9784065

  While trying to read a video stream form an IP camera using :

  



  stream = cv2.VideoCapture(src)
(grabbed, frame) = stream.read()


  



  The grabbed returns True while sometimes the frames are corrupted (probably due to high CPU load). An internal Opencv error like the following is showing on the terminal :

  



  [h264 @ 0x25e99400] error while decoding MB 87 29, bytestream -5


  



  Is there a way to catch this error ? Please note that I tried the obvious try:except with cv2.error etc. In such case of corrupted frame it would be preferable to restart the connection to the camera.

  


• atrac3 : fix error handling

  9 juillet 2013, par Luca Barbato

  atrac3 : fix error handling
  decode_tonal_components returns a proper AVERROR.
  Reported-by : Mateusz "j00ru" Jurczyk and Gynvael Coldwind
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/atrac3.c

• RTSP stream to ffmpeg problems

  14 octobre 2022, par maeek

  I'm writing a web application for managing and viewing streams from ONVIF ip-cameras.
  
It's written in nodejs. The idea is to run a child process in node and pipe output to node, then send the buffer to client and render it on canvas. I have a working solution for sending data to client and rendering it on canvas using websockets but it only works on one of my cameras.

  


  I own 2 IP cameras and both of them have rtsp server.
  
One of them(let's name it camX) kind of works with this ffmpeg command (sometimes it just stops, maybe due to packet losses) :

  


  ffmpeg -rtsp_transport tcp -re -i  -f mjpeg pipe:1


  


  But the other one(camY) returns Nonmatching transport in server reply and exits.

  


  I discovered that the camY transport is unicast but ffmpeg doesn't support this particular lower_transport as I read on ffmpeg forum.

  


  So I started looking for a solution. My first idea was to use openRTSP which works fine with both streams.
I looked at the documentation and came up with this command :
  
openRTSP -4 -c  | ffmpeg -re -i pipe:0 -f mjpeg pipe:1
  
-4 parameter returns stream to pipe in mp4 format
  
And here's another problem I ran into, ffmpeg returns :

  


  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x559a4b6ba900] moov atom not found  
pipe:0: Invalid data found when processing input


  


  Is there any way to make this work ?
I tried various solutions I found, but none of them worked.

  


  EDIT

  


  As @Gyan suggested I used -i parameter instead of -4 but it didn't solve my problem.

  


  My command :

  


  openRTSP -V -i -c -K  | ffmpeg -loglevel debug -re -i pipe:0 -f mjpeg pipe:1
  
Created receiver for "video/H264" subsession (client ports 49072-49073)
Setup "video/H264" subsession (client ports 49072-49073)
AVIFileSink::setWord(): SeekFile64 failed (err 29)
AVIFileSink::setWord(): SeekFile64 failed (err 29)
AVIFileSink::setWord(): SeekFile64 failed (err 29)
AVIFileSink::setWord(): SeekFile64 failed (err 29)
AVIFileSink::setWord(): SeekFile64 failed (err 29)
AVIFileSink::setWord(): SeekFile64 failed (err 29)
AVIFileSink::setWord(): SeekFile64 failed (err 29)
AVIFileSink::setWord(): SeekFile64 failed (err 29)
AVIFileSink::setWord(): SeekFile64 failed (err 29)
Outputting to the file: "stdout"
[avi @ 0x5612944268c0] Format avi probed with size=2048 and score=100
[avi @ 0x56129442f7a0] use odml:1
Started playing session
Receiving streamed data (signal with "kill -HUP 15028" or "kill -USR1 15028" to terminate)...
^C
[AVIOContext @ 0x56129442f640] Statistics: 16904 bytes read, 0 seeks
pipe:0: Invalid data found when processing input


  


  As you can see openRTSP command return err 29 but in meantime it outputs some data to pipe.
  
When I terminate the command ffmpeg shows that it read some data but couldn't process it.

  


  Here's the function that produces that error :

  


  void AVIFileSink::setWord(unsigned filePosn, unsigned size) {
  do {
    if (SeekFile64(fOutFid, filePosn, SEEK_SET) < 0) break;
    addWord(size);
    if (SeekFile64(fOutFid, 0, SEEK_END) < 0) break; // go back to where we were

    return;
  } while (0);

  // One of the SeekFile64()s failed, probable because we're not a seekable file
  envir() << "AVIFileSink::setWord(): SeekFile64 failed (err "
          << envir().getErrno() << ")\n";
}


  


  In my opinion it looks like it won't be able to seek file because it's a stream not a static file.
  
Any suggestion for a workaround ?