Recherche avancée

Sur d’autres sites (5828)

• What could be serve as a nullptr in cython wrapper for C++ uint8_t multidimensional array ?

  20 juillet 2020, par yose93

  I've stuck with solving of one problem. I have to fill C++ structure with yuv420p frame data in my cython wrapper :

  


  #define FR_PLANE_COUNT_MAX 8

typedef struct fr_frame_s {
    int format = 0;

    int width = 0;
    int height = 0;

    uint8_t* data[FR_PLANE_COUNT_MAX];

    int     stride[FR_PLANE_COUNT_MAX];

    int     size[FR_PLANE_COUNT_MAX];

    long long time = 0;

} fr_frame_t;




  


  Where data is just a multidimensional array with length of 8. In this array first three elements to be y, u and v byte multidimensional arrays, and the rest are just nullptr values. The next chunk of code which I need to implement on pure python just to fill the structure with according data of the above structure itself :

  


  bool VideoCapture::ConvertFrame(const AVFrame *src, fr_frame_t &dst)
{
    if(src != NULL)
    {
        for (size_t i = 0; i < FR_PLANE_COUNT_MAX; ++i)
        {
            if (src->data[i] != nullptr)
            {
                const int line = src->linesize[i];
                const int size = i == 0 ? line * src->height : int(line * (src->height / 2.0));
                dst.data[i] = (uint8_t*)malloc(size);
                memcpy(dst.data[i], src->data[i], size);

                //dst.data[i] = src->data[i];
                dst.size[i] = size;
                dst.stride[i] = src->linesize[i];
            }else{
                dst.data[i] = nullptr;
                dst.size[i] = 0;
                dst.stride[i] = 0;
            }
        }



  


  Here all the values after y, u, v arrays must be just of nullptr as it seems. So, what I can use as nullptr to fill np.ndarray after y, u, v.

  


  And my python code :

  


  def _get_read_frames(
        self,
        video: pathlib.PosixPath,
    ) -> Generator[Tuple[Union[teyefr.MetadataImage, float]], None, None]:
        """Video frames reader."""
        self._cap = cv2.VideoCapture(str(video))
        self._total_frames = self._cap.get(cv2.CAP_PROP_FRAME_COUNT)
        self._fps = math.ceil(self._cap.get(cv2.CAP_PROP_FPS))
        self._duration = self._total_frames / self._fps

        while(self._cap.isOpened()):
            _, frame = self._cap.read()

            if frame is None:
                break
            
            yuv420_frame = cv2.cvtColor(frame, cv2.COLOR_BGR2YUV)

            self._process_yuv420_frame(yuv420_frame)

        self._cap.release()
    
    def _process_yuv420_frame(self, yuv420_frame: np.ndarray) -> None:
        """To fill `self._fr_frames` list.

        Splits already converted frame into 3-channels y, u, v
        and takes all required data to fill `FRFrame` and push it.
        """
        data = np.array([])
        stride = np.array([])
        size = np.array([])
        frame_data = {}.fromkeys(FRFrame.__dataclass_fields__.keys())

        channels = (y, u, v) = cv2.split(yuv420_frame)

        for i in range(FR_PLANE_COUNT_MAX):
            if i < len(channels):
                np.concatenate(data, channels[i])
            else:
                np.concatenate(data, np.array([]))
            
        frame_data['height'], frame_data['width'], _ = yuv420_frame.shape


  


  Please advise.

  


• 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.

• How to get FFMPEG to use more GPU when encoding

  24 mars 2023, par Entropy

  so the situation is as following

  


  Im receiging 20/30 uncompressed image per second. format is either PNG or Bitmap. Each individual photo size is between 40 and 50 mb (all have same size since uncompressed).

  


  I want to encode them to a 265 lossless video and stream them to a http server using FFMPEG.
The output video is 1920x1080, so there is some downsampling.
Compression is allowed but nothing is allowed to be lost other than the down sampling.

  


  now i m still in the testing phase. i have a 500 sample image. and i m tryng to encode them as effeciently as possible.
Im using commands such as :

  


  ffmpeg  -hwaccel cuvid -f  image2  -i "0(%01d).png" -framerate 30 / 
-pix_fmt p010le -c:v hevc_nvenc -preset lossless -rc vbr_hq /
-b:v 6M -maxrate:v 10M  -vf scale=1920:1080  -c:a aac -b:a 240k result.mp4


  


  I have a powerfull modern quadro GPU and a 6 cores intel CPU and an Nvme hard drive.

  


  The usuage of the GPU when encoding is exactly 10%, CPU is circa 30-40%

  


  How can i get GPU usuage to 80% ? The machine on which im going to run the code will have at leat a quadro 4000 (maybe stronger) and i want to use it to the fullest