Recherche avancée

Sur d’autres sites (7880)

• 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

• Edit audio files on the server with Meteor

  28 décembre 2015, par Mohammed Hussein

  I am building a Meteor application to split uploaded audio files.

  I upload the audio files and store them using GridFS :

  child = Npm.require('child_process');
  
  
  
  var fs = Npm.require('fs');
  
  
  
  storagePath= fs.realpathSync(process.env.PWD+'/audio');
  
  
  
  StaticServer.add('/audio', clipsPath);

  and then using a method I split the audio file using :

  child.exec(command);

  the command is the ffmpeg command used to cut the source audio file and store it on the storagePath.

  The application worked fine locally but when I tried to deploy it to digital ocean I got errors, stating that the file /audio does not exist.
  I use mupx to deploy and the error appears after "verifying deployment".

  Here is the error :

      -----------------------------------STDERR-----------------------------------
  
      eteor-dev-bundle@0.0.0 No README data
  
      => Starting meteor app on port:80
  
  
  
      /bundle/bundle/programs/server/node_modules/fibers/future.js:245
  
                                                      throw(ex);
  
                                                            ^
  
      Error: ENOENT, no such file or directory '/bundle/bundle/audio'
  
          at Object.fs.lstatSync (fs.js:691:18)
  
          at Object.realpathSync (fs.js:1279:21)
  
          at server/startup.js:10:20
  
          at /bundle/bundle/programs/server/boot.js:249:5
  
      npm WARN package.json meteor-dev-bundle@0.0.0 No description
  
      npm WARN package.json meteor-dev-bundle@0.0.0 No repository field.
  
      npm WARN package.json meteor-dev-bundle@0.0.0 No README data
  
      => Starting meteor app on port:80
  
  
  
      /bundle/bundle/programs/server/node_modules/fibers/future.js:245
  
                                                      throw(ex);
  
                                                            ^
  
      Error: ENOENT, no such file or directory '/bundle/bundle/audio'
  
          at Object.fs.lstatSync (fs.js:691:18)
  
          at Object.realpathSync (fs.js:1279:21)
  
          at server/startup.js:10:20
  
          at /bundle/bundle/programs/server/boot.js:249:5
  
  
  
      => Redeploying previous version of the app
  
  
  
      -----------------------------------STDOUT-----------------------------------
  
  
  
      To see more logs type 'mup logs --tail=50'
  
  
  
      ----------------------------------------------------------------------------

  The main question is how to generate an output file using ffmpeg and store it in a place where I can access it and display it in the browser.

• How to store a raw RTSP video stream to a file ?

  12 janvier 2016, par Siva Prasanna

  I’m playing around with the open source FFMpeg tool. I want to save an RTSP video stream to a local file. I came across this question and I tried executing a similar command, but its not working. It doesn’t throw any error either. My command is :
  ffmpeg -i rtsp://test.vibrtech.com/mov/video.sav?MAC=00C2100F124^&channel=2^&GUID=betauser -acodec copy -vcodec copy c:/video.mp4

  but when I execute this command all I’m getting is this(with the cursor being blinked like forever, until I manually invoke ctrl+c) :

  D:\..\bin>ffmpeg -i rtsp://test.vibrtech.com/mov/video.sav?MAC=00C2100F124^&channel=2^&GUID=betauser -acodec copy -vcodec copy c:/video.mp4
  
  
  
  ffmpeg version N-77704-g68eb208 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.2.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls 
  
  --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca 
  
  --enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm 
  
  --enable-libilbc --enable-libmodplug --enable-libmp3lame 
  
  --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg 
  
  --enable-libopus --enable-librtmp --enable-libschroedinger 
  
  --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame 
  
  --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc
  
  --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp 
  
  --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid 
  
  --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55. 12.100 / 55. 12.100
  
    libavcodec     57. 21.100 / 57. 21.100
  
    libavformat    57. 21.100 / 57. 21.100
  
    libavdevice    57.  0.100 / 57.  0.100
  
    libavfilter     6. 23.100 /  6. 23.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  _

  Can anyone tell me what I’m doing wrong here ? Or is there any way this could be achieved by using other commands ?

  P.S : I’m getting the stream from this url : rtsp ://test.vibrtech.com/mov/video.sav ?MAC=00C2100F124&channel=2&GUID=betaUser