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• Export sprites/images from movie

  7 octobre 2014, par Dr.Kameleon

  OK, here’s the situation :

  • I have a .mov video, recorded using QuickTime
  • I want to split it into images (which I will use in a js animation)

  ---

  JS Code :

  function pad(num, size) {
  
      var s = num+"";
  
      while (s.length < size) s = "0" + s;
  
      return s;
  
  }
  
  
  
  
  
  $(function(){
  
      var currentIndex = 1;
  
  
  
  
  
      setInterval(function(){
  
         $("#theImage").attr("src","img/video"+pad(currentIndex,3)+".png");
  
         currentIndex++;
  
      }, 1000/24);
  
  
  
  });

  ---

  So, I tried with FFMpeg :

  ffmpeg -i "video.mov" -f image2 -vf fps=24 video%03d.jpg

  This works. But the quality of the sprites is very low.

  ffmpeg -i "video.mov" -f image2 -vf fps=24 video%03d.png

  This works too. But the quality/size of the sprite is HUGE. I mean every sprite is around 110KB, with a grand total far above the video’s size (100MB > 2MB !)

  What’s going on ?

  How can I achieve that, without losing any quality and still not having too deal with huge filesizes ?

• 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 ?

• Revision 6eb5e8ded6 : Fix fps messages for 8bit mode The addition of the high bitdepth image shifting

  24 juin 2014, par Peter de Rivaz

  Changed Paths :
   Modify /vpxenc.c

  
  
  Fix fps messages for 8bit mode

  The addition of the high bitdepth image shifting
  broke the fps measurement for the 8bit encoder.

  Change-Id : I70144fe5c9a821b582d461091c616b0a3f666cbe