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• Creating GIF from QImages with ffmpeg

  21 mars 2020, par Sierra

  I would like to generate GIF from QImage, using ffmpeg - all of that programmatically (C++). I’m working with Qt 5.6 and the last build of ffmpeg (build git-0a9e781 (2016-06-10).

  I’m already able to convert these QImage in .mp4 and it works. I tried to use the same principle for the GIF, changing format pixel and codec. GIF is generated with two pictures (1 second each), in 15 FPS.

  ## INITIALIZATION
  
  #####################################################################
  
  
  
  // Filepath : "C:/Users/.../qt_temp.Jv7868.gif"  
  
  // Allocating an AVFormatContext for an output format...
  
  avformat_alloc_output_context2(formatContext, NULL, NULL, filepath);
  
  
  
  ...
  
  
  
  // Adding the video streams using the default format codecs and initializing the codecs.
  
  stream = avformat_new_stream(formatContext, *codec);
  
  
  
  AVCodecContext * codecContext = avcodec_alloc_context3(*codec);
  
  
  
  context->codec_id       = codecId;
  
  context->bit_rate       = 400000;
  
  ...
  
  context->pix_fmt        = AV_PIX_FMT_BGR8;
  
  
  
  ...
  
  
  
  // Opening the codec...
  
  avcodec_open2(codecContext, codec, NULL);
  
  
  
  ...
  
  
  
  frame = allocPicture(codecContext->width, codecContext->height, codecContext->pix_fmt);
  
  tmpFrame = allocPicture(codecContext->width, codecContext->height, AV_PIX_FMT_RGBA);
  
  
  
  ...
  
  
  
  avformat_write_header(formatContext, NULL);
  
  
  
  ## ADDING A NEW FRAME
  
  #####################################################################
  
  
  
  // Getting in parameter the QImage: newFrame(const QImage & image)
  
  const qint32 width  = image.width();
  
  const qint32 height = image.height();
  
  
  
  // Converting QImage into AVFrame
  
  for (qint32 y = 0; y < height; y++) {
  
      const uint8_t * scanline = image.scanLine(y);
  
  
  
      for (qint32 x = 0; x < width * 4; x++) {
  
          tmpFrame->data[0][y * tmpFrame->linesize[0] + x] = scanline[x];
  
      }
  
  }
  
  
  
  ...
  
  
  
  // Scaling...
  
  if (codec->pix_fmt != AV_PIX_FMT_BGRA) {
  
      if (!swsCtx) {
  
          swsCtx = sws_getContext(codec->width, codec->height,
  
                                  AV_PIX_FMT_BGRA,
  
                                  codec->width, codec->height,
  
                                  codec->pix_fmt,
  
                                  SWS_BICUBIC, NULL, NULL, NULL);
  
      }
  
  
  
      sws_scale(swsCtx,
  
                (const uint8_t * const *)tmpFrame->data,
  
                tmpFrame->linesize,
  
                0,
  
                codec->height,
  
                frame->data,
  
                frame->linesize);
  
  }
  
  frame->pts = nextPts++;
  
  
  
  ...
  
  
  
  int gotPacket = 0;
  
  AVPacket packet = {0};
  
  
  
  av_init_packet(&packet);
  
  avcodec_encode_video2(codec, &packet, frame, &gotPacket);
  
  
  
  if (gotPacket) {
  
      av_packet_rescale_ts(paket, *codec->time_base, stream->time_base);
  
      paket->stream_index = stream->index;
  
  
  
      av_interleaved_write_frame(formatContext, paket);
  
  }

  But when I’m trying to modify the video codec and pixel format to match with GIF specifications, I’m facing some issues.
  I tried several codecs such as AV_CODEC_ID_GIF and AV_CODEC_ID_RAWVIDEO but none of them seem to work. During the initialization phase, avcodec_open2() always returns such kind of errors :

  Specified pixel format rgb24 is invalid or not supported
  
  Could not open video codec:  gif

  EDIT 17/06/2016

  Digging a little bit more, avcodec_open2() returns -22 :

  #define EINVAL          22      /* Invalid argument */

  EDIT 22/06/2016

  Here are the flags used to compile ffmpeg :

  "FFmpeg/Libav configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --disable-w32threads --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmfx --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --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"

  Did I miss a crucial one for GIF ?

  EDIT 27/06/2016

  Thanks to Gwen, I have a first output : I setted the context->pix_fmt to AV_PIX_FMT_BGR8. Btw I’m still facing some issues with the generated GIF. It’s not playing and encoding appears to fail.

  GIF generated in command lines with ffmpeg (left) . . . GIF generated programmatically (right)
  
  

  It looks like some options are not defined... also may be a wrong conversion between QImage and AVFrame ? I updated the code above. It represents a lot of code, so I tried to stay short. Don’t hesitate to ask more details.

  End of EDIT

  I’m not really familiar with ffmpeg, any kind of help would be highly appreciated. Thank you.

• Creating GIF from QImages with ffmpeg

  17 août 2016, par Sierra

  I would like to generate GIF from QImage, using ffmpeg - all of that programmatically (C++). I’m working with Qt 5.6 and the last build of ffmpeg (build git-0a9e781 (2016-06-10).

  I’m already able to convert these QImage in .mp4 and it works. I tried to use the same principle for the GIF, changing format pixel and codec. GIF is generated with two pictures (1 second each), in 15 FPS.

  ## INITIALIZATION
  
  #####################################################################
  
  
  
  // Filepath : "C:/Users/.../qt_temp.Jv7868.gif"  
  
  // Allocating an AVFormatContext for an output format...
  
  avformat_alloc_output_context2(formatContext, NULL, NULL, filepath);
  
  
  
  ...
  
  
  
  // Adding the video streams using the default format codecs and initializing the codecs.
  
  stream = avformat_new_stream(formatContext, *codec);
  
  
  
  AVCodecContext * codecContext = avcodec_alloc_context3(*codec);
  
  
  
  context->codec_id       = codecId;
  
  context->bit_rate       = 400000;
  
  ...
  
  context->pix_fmt        = AV_PIX_FMT_BGR8;
  
  
  
  ...
  
  
  
  // Opening the codec...
  
  avcodec_open2(codecContext, codec, NULL);
  
  
  
  ...
  
  
  
  frame = allocPicture(codecContext->width, codecContext->height, codecContext->pix_fmt);
  
  tmpFrame = allocPicture(codecContext->width, codecContext->height, AV_PIX_FMT_RGBA);
  
  
  
  ...
  
  
  
  avformat_write_header(formatContext, NULL);
  
  
  
  ## ADDING A NEW FRAME
  
  #####################################################################
  
  
  
  // Getting in parameter the QImage: newFrame(const QImage & image)
  
  const qint32 width  = image.width();
  
  const qint32 height = image.height();
  
  
  
  // Converting QImage into AVFrame
  
  for (qint32 y = 0; y < height; y++) {
  
      const uint8_t * scanline = image.scanLine(y);
  
  
  
      for (qint32 x = 0; x < width * 4; x++) {
  
          tmpFrame->data[0][y * tmpFrame->linesize[0] + x] = scanline[x];
  
      }
  
  }
  
  
  
  ...
  
  
  
  // Scaling...
  
  if (codec->pix_fmt != AV_PIX_FMT_BGRA) {
  
      if (!swsCtx) {
  
          swsCtx = sws_getContext(codec->width, codec->height,
  
                                  AV_PIX_FMT_BGRA,
  
                                  codec->width, codec->height,
  
                                  codec->pix_fmt,
  
                                  SWS_BICUBIC, NULL, NULL, NULL);
  
      }
  
  
  
      sws_scale(swsCtx,
  
                (const uint8_t * const *)tmpFrame->data,
  
                tmpFrame->linesize,
  
                0,
  
                codec->height,
  
                frame->data,
  
                frame->linesize);
  
  }
  
  frame->pts = nextPts++;
  
  
  
  ...
  
  
  
  int gotPacket = 0;
  
  AVPacket packet = {0};
  
  
  
  av_init_packet(&packet);
  
  avcodec_encode_video2(codec, &packet, frame, &gotPacket);
  
  
  
  if (gotPacket) {
  
      av_packet_rescale_ts(paket, *codec->time_base, stream->time_base);
  
      paket->stream_index = stream->index;
  
  
  
      av_interleaved_write_frame(formatContext, paket);
  
  }

  But when I’m trying to modify the video codec and pixel format to match with GIF specifications, I’m facing some issues.
  I tried several codecs such as AV_CODEC_ID_GIF and AV_CODEC_ID_RAWVIDEO but none of them seem to work. During the initialization phase, avcodec_open2() always returns such kind of errors :

  Specified pixel format rgb24 is invalid or not supported
  
  Could not open video codec:  gif

  EDIT 17/06/2016

  Digging a little bit more, avcodec_open2() returns -22 :

  #define EINVAL          22      /* Invalid argument */

  EDIT 22/06/2016

  Here are the flags used to compile ffmpeg :

  "FFmpeg/Libav configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --disable-w32threads --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmfx --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --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"

  Did I miss a crucial one for GIF ?

  EDIT 27/06/2016

  Thanks to Gwen, I have a first output : I setted the context->pix_fmt to AV_PIX_FMT_BGR8. Btw I’m still facing some issues with the generated GIF. It’s not playing and encoding appears to fail.

  GIF generated in command lines with ffmpeg (left) . . . GIF generated programmatically (right)
  
  

  It looks like some options are not defined... also may be a wrong conversion between QImage and AVFrame ? I updated the code above. It represents a lot of code, so I tried to stay short. Don’t hesitate to ask more details.

  End of EDIT

  I’m not really familiar with ffmpeg, any kind of help would be highly appreciated. Thank you.

• Issues with encoded video in Chrome playback

  4 novembre 2022, par Michael Joseph Aubry

  Chrome is very particular about how a video is encoded. An issue I am facing with a specific type of video is seeked either does not get called at all or at least within a 20s period of time within certain frames.

  


  I can consistently repeat this issue using this muxer https://github.com/redbrain/ytdl-core-muxer/blob/main/index.js

  


  When I paint each frame in puppeteer Lambda there are certain frames where either seeked never gets called or the 20s timeout is called before the frame can resolve.

  


  Here is an example of a log sequence for this particular frame that fails

  


  When I re-encode this video, simply by running ffmpeg -i VIDEO_URL then try with the new one there are no issues.

  


  In order to see the differences on a frame level I run ffprobe -show_frames goodvideo.mp4 > good.txt && ffprobe -show_frames badvideo.mp4 > bad.txt and here is what I see with the frames around the 117s mark where the first sign of corruption occurs

  


  Good Frame @ 117s

  


  [FRAME]
media_type=video
stream_index=0
key_frame=0
pts=7020013
pts_time=117.000217
pkt_dts=7020013
pkt_dts_time=117.000217
best_effort_timestamp=7020013
best_effort_timestamp_time=117.000217
pkt_duration=1001
pkt_duration_time=0.016683
pkt_pos=27029408
pkt_size=1741
width=1920
height=1080
pix_fmt=yuv420p
sample_aspect_ratio=1:1
pict_type=B
coded_picture_number=7014
display_picture_number=0
interlaced_frame=0
top_field_first=0
repeat_pict=0
color_range=tv
color_space=bt709
color_primaries=bt709
color_transfer=bt709
chroma_location=left
[/FRAME]


  


  Bad Frame @ 117s

  


  [FRAME]
media_type=video
stream_index=0
key_frame=0
pts=117000
pts_time=117.000000
pkt_dts=117000
pkt_dts_time=117.000000
best_effort_timestamp=117000
best_effort_timestamp_time=117.000000
pkt_duration=16
pkt_duration_time=0.016000
pkt_pos=20592998
pkt_size=18067
width=1920
height=1080
pix_fmt=yuv420p
sample_aspect_ratio=1:1
pict_type=P
coded_picture_number=7011
display_picture_number=0
interlaced_frame=0
top_field_first=0
repeat_pict=0
color_range=tv
color_space=bt709
color_primaries=bt709
color_transfer=bt709
chroma_location=left
[/FRAME]


  


  Does anyone know the differences and why the bad frame is causing my rendering function to have issues seeking ?

  


  This is how I am muxing the bad video, Im trying to avoid re-encoding, but by re-encoding it seems to fix the issue. Are there any settings I can apply to avoid re-encoding while making the video more durable on Chrome ?

  


  // default export: the ffmpeg muxer
const ytmux = (link, options: any = {}) => {
  const result = new stream.PassThrough({
    highWaterMark: options.highWaterMark || 1024 * 512
  });

  ytdl.getInfo(link, options).then((info: videoInfo) => {
    let audioStream: Readable = ytdl.downloadFromInfo(info, {
      ...options,
      quality: "highestaudio"
    });
    let videoStream: Readable = ytdl.downloadFromInfo(info, {
      ...options,
      quality: "highestvideo"
    });
    // create the ffmpeg process for muxing
    let ffmpegProcess: any = cp.spawn(
      ffmpegPath.path,
      [
        // supress non-crucial messages
        "-loglevel",
        "8",
        "-hide_banner",
        // input audio and video by pipe
        "-i",
        "pipe:3",

        "-i",
        "pipe:4",

        // map audio and video correspondingly
        "-map",
        "0:v",
        "-map",
        "1:a",

        // no need to change the codec
        "-c",
        "copy",

        // Allow output to be seekable, which is needed for mp4 output
        "-movflags",
        "frag_keyframe+empty_moov",

        "-fflags",
        "+genpts",

        "-f",
        "matroska",

        "pipe:5"
      ],
      {
        // no popup window for Windows users
        windowsHide: true,
        stdio: [
          // silence stdin/out, forward stderr,
          "inherit",
          "inherit",
          "inherit",
          // and pipe audio, video, output
          "pipe",
          "pipe",
          "pipe"
        ]
      }
    );

    audioStream.pipe(ffmpegProcess.stdio[4]);
    videoStream.pipe(ffmpegProcess.stdio[3]);
    ffmpegProcess.stdio[5].pipe(result);
  });
  return result;
};