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• Ffmpeg decoder yuv420p

  4 décembre 2015, par user2466514

  I work on a video player yuv420p with ffmpeg but it’s not working and i can’t find out why. I spend the whole week on it...

  So i have a test which just decode some frame and read it, but the output always differ, and it’s really weird.

  I use a video (mp4 yuv420p) which color one black pixel in more each frame :

  For the video, put http://sendvid.com/b1sgf8r1 on a website like http://www.telechargerunevideo.com/en/

  VideoContext is just a little struct :

  struct  VideoContext {
  
  
  
  unsigned int      currentFrame;
  
  std::size_t       size;
  
  int               width;
  
  int               height;
  
  bool              pause;
  
  AVFormatContext*  formatCtx;
  
  AVCodecContext*   codecCtxOrig;
  
  AVCodecContext*   codecCtx;
  
  int               streamIndex;
  
  };

  So i have a function to count the number of black pixels :

  std::size_t  checkFrameNb(const AVFrame* frame) {
  
  
  
      std::size_t  nb = 0;
  
  
  
      for (int y = 0; y < frame->height; ++y) {
  
        for (int x = 0 ; x < frame->width; ++x) {
  
  
  
          if (frame->data[0][(y * frame->linesize[0]) + x] == BLACK_FRAME.y
  
              && frame->data[1][(y / 2 * frame->linesize[1]) + x / 2] == BLACK_FRAME.u
  
              && frame->data[2][(y / 2 * frame->linesize[2]) + x / 2] == BLACK_FRAME.v)
  
            ++nb;
  
        }
  
      }
  
      return nb;
  
    }

  And this is how i decode one frame :

  const AVFrame*  VideoDecoder::nextFrame(entities::VideoContext& context) {
  
  
  
    int frameFinished;
  
    AVPacket packet;
  
  
  
    // Allocate video frame
  
    AVFrame*  frame = av_frame_alloc();
  
    if(frame == nullptr)
  
      throw;
  
  
  
    // Initialize frame->linesize
  
    avpicture_fill((AVPicture*)frame, nullptr, AV_PIX_FMT_YUV420P, context.width, context.height);
  
  
  
    while(av_read_frame(context.formatCtx, &packet) >= 0) {
  
  
  
      // Is this a packet from the video stream?
  
      if(packet.stream_index == context.streamIndex) {
  
        // Decode video frame
  
        avcodec_decode_video2(context.codecCtx, frame, &frameFinished, &packet);
  
  
  
        // Did we get a video frame?
  
        if(frameFinished) {
  
  
  
          // Free the packet that was allocated by av_read_frame
  
          av_free_packet(&packet);
  
          ++context.currentFrame;
  
          return frame;
  
        }
  
      }
  
    }
  
  
  
    // Free the packet that was allocated by av_read_frame
  
    av_free_packet(&packet);
  
    throw core::GlobalException("nextFrame", "Frame decode failed");
  
  }

  There is already something wrong ?

  Maybe the context initialization will be useful :

  entities::VideoContext  VideoLoader::loadVideoContext(const char* file,
  
                                                        const int width,
  
                                                        const int height) {
  
  
  
    entities::VideoContext  context;
  
  
  
    // Register all formats and codecs
  
    av_register_all();
  
  
  
    context.formatCtx = avformat_alloc_context();
  
  
  
  
  
    // Open video file
  
    if(avformat_open_input(&context.formatCtx, file, nullptr, 0) != 0)
  
      throw; // Couldn't open file
  
  
  
    // Retrieve stream information
  
    if(avformat_find_stream_info(context.formatCtx, nullptr) > 0)
  
      throw; // Couldn't find stream information
  
  
  
    // Dump information about file onto standard error
  
    //av_dump_format(m_formatCtx, 0, file, 1);
  
  
  
  
  
    // Find the first video stream because we don't need more
  
    for(unsigned int i = 0; i < context.formatCtx->nb_streams; ++i)
  
      if(context.formatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
  
        context.streamIndex = i;
  
        context.codecCtx = context.formatCtx->streams[i]->codec;
  
        break;
  
      }
  
    if(context.codecCtx == nullptr)
  
      throw; // Didn't find a video stream
  
  
  
  
  
    // Find the decoder for the video stream
  
    AVCodec*  codec = avcodec_find_decoder(context.codecCtx->codec_id);
  
    if(codec == nullptr)
  
      throw; // Codec not found
  
    // Copy context
  
    if ((context.codecCtxOrig = avcodec_alloc_context3(codec)) == nullptr)
  
      throw;
  
    if(avcodec_copy_context(context.codecCtxOrig, context.codecCtx) != 0)
  
      throw; // Error copying codec context
  
    // Open codec
  
    if(avcodec_open2(context.codecCtx, codec, nullptr) < 0)
  
      throw; // Could not open codec
  
  
  
    context.currentFrame = 0;
  
    decoder::VideoDecoder::setVideoSize(context);
  
    context.pause = false;
  
    context.width = width;
  
    context.height = height;
  
  
  
    return std::move(context);
  
  }

  I know it’s not a little piece of code, if you have any idea too make an exemple more brief, go on.

  And if someone have an idea about this issue, there is my output :

  9 - 10 - 12 - 4 - 10 - 14 - 11 - 8 - 9 - 10

  But i want :

  1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10

  PS :
  get fps and video size are copy paste code of opencv

• Merging audio(aac) and video (h.264 in mp4 container) into a mp4 container using Xuggler

  26 août 2016, par Handroid

  Here is the code I am using

      String filenamevideo = videoFilePath;(video.mp4)
  
  
  
      String filenameaudio = audioAACFilePath; (audio.aac)
  
  
  
  
  
  
  
      IMediaWriter mWriter = ToolFactory.makeWriter(videoWithAudioFilePath); // output
  
      // file
  
  
  
      IContainer containerVideo = IContainer.make();
  
      IContainer containerAudio = IContainer.make();
  
  
  
      if (containerVideo.open(filenamevideo, IContainer.Type.READ, null) < 0)
  
          throw new IllegalArgumentException("Cant find " + filenamevideo);
  
  
  
      if (containerAudio.open(filenameaudio, IContainer.Type.READ, null) < 0)
  
          throw new IllegalArgumentException("Cant find " + filenameaudio);
  
  
  
      int numStreamVideo = containerVideo.getNumStreams();
  
      int numStreamAudio = containerAudio.getNumStreams();    
  
  
  
      int videostreamt = -1; // this is the video stream id
  
      int audiostreamt = -1;
  
  
  
      IStreamCoder videocoder = null;
  
  
  
      for (int i = 0; i < numStreamVideo; i++) {
  
          IStream stream = containerVideo.getStream(i);
  
          IStreamCoder code = stream.getStreamCoder();
  
  
  
          if (code.getCodecType() == ICodec.Type.CODEC_TYPE_VIDEO) {
  
              videostreamt = i;
  
              videocoder = code;
  
              break;
  
          }
  
  
  
      }
  
  
  
      for (int i = 0; i < numStreamAudio; i++) {
  
          IStream stream = containerAudio.getStream(i);
  
          IStreamCoder code = stream.getStreamCoder();
  
  
  
          if (code.getCodecType() == ICodec.Type.CODEC_TYPE_AUDIO) {
  
              audiostreamt = i;
  
              break;
  
          }
  
  
  
      }
  
  
  
      if (videostreamt == -1)
  
          throw new RuntimeException("No video steam found");
  
      if (audiostreamt == -1)
  
          throw new RuntimeException("No audio steam found");
  
  
  
      if (videocoder.open() < 0)
  
          throw new RuntimeException("Cant open video coder");
  
      IPacket packetvideo = IPacket.make();
  
  
  
      IStreamCoder audioCoder = containerAudio.getStream(audiostreamt).getStreamCoder();
  
  
  
      if (audioCoder.open() < 0)
  
          throw new RuntimeException("Cant open audio coder");
  
  
  
      mWriter.addAudioStream(0, 0, ICodec.ID.CODEC_ID_AAC, audioCoder.getChannels(),audioCoder.getSampleRate());
  
  
  
      mWriter.addVideoStream(1, 0, ICodec.ID.CODEC_ID_H264, videocoder.getWidth(), videocoder.getHeight());
  
  
  
  
  
      IPacket packetaudio = IPacket.make();
  
  
  
      while (containerVideo.readNextPacket(packetvideo) >= 0 || containerAudio.readNextPacket(packetaudio) >= 0) {
  
  
  
          if (packetvideo.getStreamIndex() == videostreamt) {
  
  
  
              // video packet
  
              IVideoPicture picture = IVideoPicture.make(videocoder.getPixelType(), videocoder.getWidth(),
  
                      videocoder.getHeight());
  
              int offset = 0;
  
              while (offset < packetvideo.getSize()) {
  
                  int bytesDecoded = videocoder.decodeVideo(picture, packetvideo, offset);
  
                  if (bytesDecoded < 0)
  
                      throw new RuntimeException("bytesDecoded not working");
  
                  offset += bytesDecoded;
  
                  if (picture.isComplete()) {
  
                      // System.out.println(picture.getPixelType());
  
                      mWriter.encodeVideo(1, picture);
  
                  }
  
              }
  
          }
  
  
  
          if (packetaudio.getStreamIndex() == audiostreamt) {
  
              // audio packet
  
              IAudioSamples samples = IAudioSamples.make(512, audioCoder.getChannels(), IAudioSamples.Format.FMT_S32);
  
              int offset = 0;
  
              while (offset < packetaudio.getSize()) {
  
                  int bytesDecodedaudio = audioCoder.decodeAudio(samples, packetaudio, offset);
  
                  if (bytesDecodedaudio < 0)
  
                      throw new RuntimeException("could not detect audio");
  
                  offset += bytesDecodedaudio;
  
                  if (samples.isComplete()) {
  
                      mWriter.encodeAudio(0, samples);
  
                  }
  
              }
  
  
  
          }           
  
      }

  The output file (mp4) is generating , but unable to play it using (vlc) and in JavaFX scene media.

  Please help me with the inputs on the above code I’m using it in a correct way (Or) help me with the possible solution for merging audio(aac) and video(h264) to mp4 container.

  Thank in advance.

• cv2.VideoCapture on python

  27 décembre 2015, par pandasarebest

  I am running the following code :

  import numpy as np
  
  import cv2
  
  import os
  
  
  
  count = 0
  
  
  
  cap = cv2.VideoCapture("/home/simon/PROJECT/real_data/00000020.mp4")
  
  
  
  while not cap.isOpened():
  
      cap = cv2.VideoCapture("./00000020.mp4")
  
      cv2.waitKey(1000)
  
      print "Wait for the header"
  
  
  
  pos_frame = cap.get(cv2.cv.CV_CAP_PROP_POS_FRAMES)
  
  while True:
  
      flag, frame = cap.read()
  
      if flag:
  
          # The frame is ready and already captured
  
          cv2.imshow('video', frame)
  
          pos_frame = cap.get(cv2.cv.CV_CAP_PROP_POS_FRAMES)
  
          print str(pos_frame)+" frames"
  
      else:
  
          # The next frame is not ready, so we try to read it again
  
          cap.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, pos_frame-1)
  
          print "frame is not ready"
  
          # It is better to wait for a while for the next frame to be ready
  
          cv2.waitKey(1000)
  
  
  
      if cv2.waitKey(10) & 0xFF == 27:
  
          break
  
      if cap.get(cv2.cv.CV_CAP_PROP_POS_FRAMES) ==       cap.get(cv2.cv.CV_CAP_PROP_FRAME_COUNT):
  
      # If the number of captured frames is equal to the total number of frames,
  
      # we stop
  
      break
  
  
  
  
  
  if ret == True:
  
      frame = cv2.VideoCapture.grab()
  
      frame = 'frame%d' % count 
  
  
  
      cv2.imwrite('frame%d.png', frame)
  
  
  
      count += 1
  
  else:
  
      print 'stopped at' + count
  
      break

  And whenever I run it, it loops on the while not loop, printing "wait for header".
  There is never an error code or anything like that either.

  I have tried to run it as a more simple piece of code, where it doesnt have all these checks, and again that doesn’t throw any errors.

  I am attempting to run this code to open a video, and then save the frames as png files throughout the video.

  Does anyone spot any particular problems with the code ?
  Or alternatively does anyone know a piece of code that would do what i want more efficiently, as I have trawled through google searches and stack overflow a lot recently and haven’t found anything

  Thanks in advance
  Panda