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• Crash in ffmpeg avcodec_free_context in one application but not in other

  5 novembre 2017, par geekowl

  I am building an application in C++ on Windows 10 using Microsoft Visual Studio 2012 Professional.

  I have created a wrapper library around ffmpeg (libavcodec) to encode video in H.264 format using libx264. This wrapper contains following functions :

  Initialize()
  
  Open()
  
  EncodeFrame()
  
  Close()
  
  Uninitialize()

  I created a test application to test the wrapper library. The test application works perfectly fine.

  When I use the wrapper library in my actual main application, the main application crashes in Close() API. Inside close, it crashes in avcodec_free_context(). The difference between the main application and the test application is that the main application links with some more dependent libraries that test application does not link with.

  To debug the problem in the main application, I put avcodec_free_context() in Open() after the context is allocated. The crash occurs if avcodec_free_context() is put at a certain point as shown below.

  pCodecContext = avcodec_alloc_context3(pCodec);
  
  
  
  // <---- No crash here.
  
  
  
  pCodecContext->bit_rate = 200000;
  
  pCodecContext->width = 320;
  
  pCodecContext->height = 240;
  
  .
  
  .
  
  .
  
  if (pCodec->id == AV_CODEC_ID_H264)
  
  {
  
      av_opt_set(pCodecContext->priv_data, "preset", "slow", 0);
  
      av_opt_set(pCodecContext->priv_data, "tune", "zerolatency", 0);
  
  }
  
  
  
  pCodecContext->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
  
  
  // <-- No crash here
  
  
  
  if (avcodec_open2(pCodecContext, pCodec, NULL) < 0)
  
  {
  
      return -1;
  
  }
  
  
  
  // <-- Crash here [avcodec_free_context(&pCodecContext);]

  What is a correct approach to identify and resolve this problem ?

  Thanks in advance.

  Update

  I found out that ffmpeg was built using gcc. That was causing the crash. I rebuilt ffmpeg using Visual Studio. That solved problem.

• Why doesn't the ffmpeg output display the stream in the browser ? [closed]

  10 mai 2024, par Tebyy

  Why is it that when I create a livestream in Python using ffmpeg, and then I open the browser and visit the page, the page keeps loading continuously, and in PyCharm logs, I see binary data ? There are no errors displayed, and the code seems correct to me. I even tried saving to a file for testing purposes, and when I play the video, everything works fine. Does anyone know what might be wrong here ?

  


  Code :

  


  def generate_frames():
    cap = cv2.VideoCapture(os.path.normpath(app_root_dir().joinpath("data/temp", "video-979257305707693982.mp4")))
    while cap.isOpened():
        ret, frame = cap.read()
        if not ret:
            break

        yield frame


@app.route('/video_feed')
def video_feed():
    ffmpeg_command = [
        'ffmpeg', '-f', 'rawvideo', '-pix_fmt', 'bgr24',
        '-s:v', '1920x1080', '-r', '60',
        '-i', '-', '-vf', 'setpts=2.5*PTS', # Video Speed
        '-c:v', 'libvpx-vp9', '-g', '60', '-keyint_min', '60',
        '-b:v', '6M', '-minrate', '4M', '-maxrate', '12M', '-bufsize', '8M',
        '-crf', '0', '-deadline', 'realtime', '-tune', 'psnr', '-quality', 'good',
        '-tile-columns', '6', '-threads', '8', '-lag-in-frames', '16',
        '-f', 'webm', '-'
    ]
    ffmpeg_process = subprocess.Popen(ffmpeg_command, stdin=subprocess.PIPE, stderr=subprocess.PIPE, bufsize=-1)
    frames_generator = generate_frames()
    for frame in frames_generator:
        ffmpeg_process.stdin.write(frame)
        ffmpeg_process.stdin.flush()

    ffmpeg_process.stdin.close()
    ffmpeg_process.wait()

    def generate_video_stream(process):
        startTime = time.time()
        buffer = []
        sentBurst = False
        for chunk in iter(lambda: process.stderr.read(4096), b''):
            buffer.append(chunk)

            # Minimum buffer time, 3 seconds
            if sentBurst is False and time.time() > startTime + 3 and len(buffer) > 0:
                sentBurst = True
                for i in range(0, len(buffer) - 2):
                    print("Send initial burst #", i)
                    yield buffer.pop(0)

            elif time.time() > startTime + 3 and len(buffer) > 0:
                yield buffer.pop(0)

            process.poll()
            if isinstance(process.returncode, int):
                if process.returncode > 0:
                    print('FFmpeg Error', process.returncode)

                break

    return Response(stream_with_context(generate_video_stream(ffmpeg_process)), mimetype='video/webm', content_type="video/webm; codecs=vp9", headers=Headers([("Connection", "close")]))



  


• fate : add a case for ticket #3229

  12 août 2019, par Zhong Li

  fate : add a case for ticket #3229
  Reviewed-by : Michael Niedermayer <michael@niedermayer.cc>
  
  Reviewed-by : Thilo Borgmann <thilo.borgmann@mail.de>
  
  Signed-off-by : Zhong Li <zhong.li@intel.com>
  

  • [DH] tests/fate/video.mak
  • [DH] tests/ref/fate/mjpeg-ticket3229