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• How to create FFMPEG command that position a movie in a frame

  31 janvier 2019, par S.T

  I want to create FFMPEG command that takes 2 movies and position it inside a frame at a specified x and y next to each other and then create one movie from it.

  This is a command i did which create a movie that puts 2 movies next to each other with a space of 10 pixels between them.

  complexCommand = new String[]
  "-i", tempPath1, "-i", tempPath2, "-strict","experimental",
  "-filter_complex",
  "[0:v:0]pad=iw*2:ih+20:color=white[bg] ;"+
  "[bg][1:v:0]overlay=w+10:h+10",
  "-s", "320x240","-r", "30", "-b", "15496k", "-vcodec", "mpeg4",
  "-ab", "48000", "-ac", "2", "-ar", "22050",

  The problem is that i want more abilities like control the position of each movies (multiple movies), an explanation or an example how to use the padding and the position of the movies.

  Thanks a lot.

• How to check if a .mp4 file is not corrupt and not missing movie frames or audio segments programmatically

  2 novembre 2019, par forgodsakehold

  With youtube-dl I was able to download quite a couple of .mp4 files. However, I have just discovered, after manually playing some of them, that they are missing movie frames in some parts while still playing audio (so a blank screen is shown), or missing audio while still playing movie frames.

  Hence,
  (1) Why doesn’t youtube-dl detect or warn against such a scenario ? It looks like the movie segments and audio track were merged and .mp4 produced without any warning. Is there a way to configure youtube-dl to detect such cases and redownload the movie ?
  (2) Otherwise, are there other ways to detect such cases programmatically ? (considering that one might have thousands of such .mp4 files and may not be able to manually go thru all of them ?) A solution with FFmpeg or php will be appreciated.

• Create movie programatically with ffmpeg

  16 janvier 2019, par Martin Delille

  I would like to create a movie programatically with ffmpeg.

  Here is my code :

  QString fileName = "test.mov";
  
  static char errorString[AV_ERROR_MAX_STRING_SIZE];
  
  
  
  printf("Video encoding\n");
  
  
  
  AVOutputFormat *outputFormat = av_guess_format(nullptr, fileName.toStdString().c_str(), nullptr);
  
  
  
  if (outputFormat == nullptr) {
  
      qDebug() << "Could not find suitable format for" << fileName;
  
      return false;
  
  }
  
  
  
  enum AVCodecID codec_id = AV_CODEC_ID_MJPEG;
  
  
  
  qDebug() << "Format Name:" << outputFormat->name;
  
  qDebug() << "Format Video Codec:" << outputFormat->video_codec;
  
  outputFormat->video_codec = codec_id;
  
  
  
  /// allocate the output media context, formatContext
  
  AVFormatContext *formatContext = avformat_alloc_context();
  
  formatContext->oformat = outputFormat;
  
  
  
  // find the mpeg1 video encoder
  
  AVCodec *codec = avcodec_find_encoder(codec_id);
  
  
  
  if (!codec) {
  
      qDebug() << "codec not found";
  
      return false;
  
  }
  
  
  
  qDebug() << "Codec name:" << codec->name;
  
  
  
  AVStream *videoStream = avformat_new_stream(formatContext, codec);
  
  // put sample parameters
  
  videoStream->codecpar->bit_rate = 400000;
  
  videoStream->codecpar->width = width;
  
  videoStream->codecpar->height = height;
  
  videoStream->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
  
  videoStream->codecpar->format = AV_PIX_FMT_YUVJ422P;
  
  videoStream->time_base.num = 1;
  
  videoStream->time_base.den = 25;
  
  
  
  AVCodecContext *codecContext = avcodec_alloc_context3(nullptr);
  
  codecContext->codec_id = codec_id;
  
  codecContext->codec_type = AVMEDIA_TYPE_VIDEO;
  
  codecContext->width = width;
  
  codecContext->height = height;
  
  codecContext->time_base.num = 1;
  
  codecContext->time_base.den = 25;
  
  codecContext->pix_fmt = AV_PIX_FMT_YUVJ422P;
  
  
  
  if (int error = avcodec_parameters_to_context(codecContext, videoStream->codecpar)) {
  
      qDebug() << "Error parameting the context:" << av_make_error_string(errorString, AV_ERROR_MAX_STRING_SIZE, error);
  
      return false;
  
  }
  
  
  
  // open it
  
  if (int error = avcodec_open2(codecContext, codec, nullptr)) {
  
      qDebug() << "Could not open codec:" << av_make_error_string(errorString, AV_ERROR_MAX_STRING_SIZE, error);
  
      return false;
  
  }
  
  
  
  // alloc image and output buffer
  
  AVFrame *frame = av_frame_alloc();
  
  frame->format = codecContext->pix_fmt;
  
  frame->width = codecContext->width;
  
  frame->height = codecContext->height;
  
  
  
  if (int error = av_image_alloc(frame->data, frame->linesize, frame->width, frame->height, static_cast<enum avpixelformat="avpixelformat">(frame->format), 0)) {
  
      qDebug() &lt;&lt; "Error allocating image data:" &lt;&lt; av_make_error_string(errorString, AV_ERROR_MAX_STRING_SIZE, error);
  
      return false;
  
  }
  
  
  
  // Open the output file, if needed
  
  if (!(outputFormat->flags &amp; AVFMT_NOFILE)) {
  
      if (avio_open(&amp;formatContext->pb, fileName.toStdString().c_str(), AVIO_FLAG_WRITE) &lt; 0) {
  
          qDebug() &lt;&lt; "Could not open" &lt;&lt; fileName;
  
          return false;
  
      }
  
  }
  
  
  
  // some formats want stream headers to be separate
  
  if (formatContext->oformat->flags &amp; AVFMT_GLOBALHEADER) {
  
      codecContext->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  
  }
  
  
  
  if (int error = avformat_write_header(formatContext, nullptr)) {
  
      qDebug() &lt;&lt; "error writing header:" &lt;&lt; av_make_error_string(errorString, AV_ERROR_MAX_STRING_SIZE, error);
  
      return false;
  
  }
  
  </enum>

  Unfortunately, when I execute it I have the following output :

  Format Name: mov
  
  Format Video Codec: 27
  
  Codec name: mjpeg
  
  [mov @ 0x1048c7000] Could not find tag for codec none in stream #0, codec not currently supported in container
  
  error writing header: Invalid argument

  What am I doing wrong ?