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• FFMPEG Add recording to this command

  4 août 2019, par Jorge Forero

  Raspberry Pi IP camera on my network broadcasting to a web browser. I want to save 10 minutes long video clips. This is the line :

  raspivid  -t -0 -w 1080 -h 720 -awb auto -fps 30 -b 1200000 -o - |ffmpeg -loglevel quiet -i - -vcodec copy -an -f flv -metadata streamName=myStream tcp://0.0.0.0:6666& 

  Following a youtube tutorial I managed to watch my rpi ip camera on the browser but I want to record myself sleeping to detect any breath interruption.

  raspivid  -t -0 -w 1080 -h 720 -awb auto -fps 30 -b 1200000 -o - |ffmpeg -loglevel quiet -i - -vcodec copy -an -f flv -metadata streamName=myStream tcp://0.0.0.0:6666&

  Works fine ! I only want to add recording to a file 10 minutes videos (in chronological order if it’s possible)

• Get data from native process on Android

  22 octobre 2013, par Gonzalo Solera

  I´m converting a video with my app, and I got it using the FFmpeg library. I´m using a static compiled version of FFmpeg and I run my command like this :

          //Conversion video
  
          try {
  
              Process p = Runtime.getRuntime().exec("data/data/package/cache/ffmpeg -i "   path   " -g "   String.valueOf(keyFrames)   " -s 720x480 -vcodec libx264 -an -y /sdcard/lowResolution.mp4");
  
              p.waitFor();
  
          } catch (IOException e) {
  
              // TODO Auto-generated catch block
  
              e.printStackTrace();
  
          } catch (InterruptedException e) {
  
              // TODO Auto-generated catch block
  
              e.printStackTrace();
  
          }
  
          Log.d(TAG, "Video convertido"); 

  It works well but it takes me too much time, so I would like to put a progress bar, so I should need to read output events of the process (the same output I can see when I execute the command in terminal) in order to know how long will it take or something like that.

  Sorry for my english and thanks for help !!

• Are avcodec_send_packet and avcodec_receive_frame thread safe ?

  6 novembre 2022, par nckm

  I am trying to implement video decoding application with libav decoder.
Most libav examples are built like this (pseudocode) :

  


  while true {
    auto packet = receive_packet_from_network();
    avcodec_send_packet(packet);
    auto frame = alloc_empty_frame();
    int r = avcodec_receive_frame(&frame);
    if (r==0) {
        send_to_render(frame);
    }
}


  


  Above is pseudocode.
Anyway, with this traditional cycle, when I wait receive frame complete and then wait rendering complete and then wait next data received from network incoming decoder buffer becomes empty. No HW decoder pipeline, low decode performance.
Additional limitation in my application - I know exactly that one received packet from network directly corresponds to one decoded frame.

  


  Besides that, I would like to make solution faster. For that I want to split this cycle into 2 different threads like this :

  


  //thread one
while true {
    auto packet = receive_packet_from_network();
    avcodec_send_packet(packet);
}
//thread two
while true {
    auto frame = alloc_empty_frame();
    int r = avcodec_receive_frame(&frame);
    if (r==0) {
        send_to_render(frame);
    }


  


  Purpose to split cycle into 2 different threads is to keep incoming decoder buffer always feed enough, mostly full. Only in that case I guess HW decoder I expect to use will be happy to work constantly pipelined. Of cause, I need thread synchronization mechanisms, not shown here just for simplicity. Of cause when EGAIN is returned from avcodec_send_packet() or avcodec_receive_frame() I need to wait for other thread makes its job feeding incoming buffer or fetching ready frames. That is another story.

  


  Besides that, this threading solution does not work for me with random segmentation faults. Unfortunately I cannot find any libav documentation saying explicitly if such method is acceptable or not, are avcodec_send_packet() and avcodec_receive_frame() calls thread safe or not ?

  


  So, what is best way to load HW decoder pipeline ? For me it is obvious that traditional poll cycles shown in any libav examples are not effective.