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• Suppress black margins on the sides of an animation

  26 avril 2018, par Clinton Winant

  I need to make an animation out of a collection of jpeg images. The image size, as given by display, is 1200x900. I can control the size of the jpg images with convert, but not sure what a good size would be. I use the following ffmpeg call :

  ffmpeg -f image2 -i img%04d.jpg -r 24  sound.avi

  In spite of a long string of warnings like

  Past duration 0.879997 too large

  sound.avi is produced, however the animation includes black right and left margins (see attached screen shot of the first frame)

  

  that I need to suppress. I am under the impression that the 4x3 format of the jpg images is standard ? I view the animation with

  mplayer sound.avi

  The OS is Debian buster

  Further experiments suggest that the black margins disappear if the jpg files have an aspect ratio 16:9. Is that the only AR possible ?

  The output of

  ffmpeg -f image2 -i img%04d.jpg -vf cropdetect -vframes 5 -f null

  requested by @Gyan is

  ffmpeg version 3.4.2-2 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 7 (Debian 7.3.0-15)
  
    configuration: --prefix=/usr --extra-version=2 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  
    libavutil      55. 78.100 / 55. 78.100
  
    libavcodec     57.107.100 / 57.107.100
  
    libavformat    57. 83.100 / 57. 83.100
  
    libavdevice    57. 10.100 / 57. 10.100
  
    libavfilter     6.107.100 /  6.107.100
  
    libavresample   3.  7.  0 /  3.  7.  0
  
    libswscale      4.  8.100 /  4.  8.100
  
    libswresample   2.  9.100 /  2.  9.100
  
    libpostproc    54.  7.100 / 54.  7.100
  
  Trailing options were found on the commandline.
  
  Input #0, image2, from 'img%04d.jpg':
  
    Duration: 00:00:00.40, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 1200x900 [SAR 150:150 DAR 4:3], 25 fps, 25 tbr, 25 tbn, 25 tbc

• Black video when using ffplay of received data over upd [closed]

  4 février 2023, par Alexandru-Marian Buza

  I'm encoding frames from a id3d11texture2d, and the receive packet size is around 70-80.
When i'm sending over udp, and use ffplay to show the video, i get a black screen.
Resolution and fps are well determined by ffplay.

  


  AcquiredBuffer.Attach(Buffer.MetaData.pSurface);

            ID3D11Texture2D* texture;
            ID3D11Texture2D* stagingTexture;
            AcquiredBuffer->QueryInterface(IID_PPV_ARGS(&texture));
            
            texture->GetDesc(&desc);
            desc.Usage = D3D11_USAGE_STAGING;
            desc.CPUAccessFlags = D3D11_CPU_ACCESS_READ;
            desc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
            desc.BindFlags = 0;
            desc.MiscFlags = 0;
            hr = m_Device->Device->CreateTexture2D(&desc, NULL, &stagingTexture);
            if (stagingTexture != 0) {
                m_Device->DeviceContext->CopyResource(stagingTexture, texture);
                D3D11_MAPPED_SUBRESOURCE mappedData;
                m_Device->DeviceContext->Map(stagingTexture, 0, D3D11_MAP_READ, 0, &mappedData);
                
                memcpy(frame->data[0], mappedData.pData, mappedData.DepthPitch);
                auto ret = avcodec_send_frame(codec, frame);
                if (ret < 0) {
                    writeText("Send frame failed");
                }
                else {
                    while (ret >= 0) {
                        ret = avcodec_receive_packet(codec, packet);
                        for (int i = 0; i < packet->size; i++) {
                            if (packet->data[i] != 0) {
                            }
                        }
                        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
                            break;
                        }
                        else if (ret < 0) {
                            writeText("Error durring encoding");
                        }
                        if (sendto(s, (char*)packet->data, packet->size * sizeof(uint8_t), 0, (sockaddr*)&dest, sizeof(dest)) == SOCKET_ERROR) {
                            writeText("Failed to send frame");
                        }
                        av_packet_unref(packet);
                    }
                }
                
                m_Device->DeviceContext->Unmap(stagingTexture, 0);
                stagingTexture->Release();


  


• python3 openCV VideoCapture only black image (Raspbian Stretch)

  21 juin 2018, par PrimuS

  I have a little python function that analyzes a video, chunks it into one image per second and gives me the most dominant color for that image. (Code can be found here : https://github.com/primus852/python-movie-barcode)

  This works great on my Windows testing environment. However, on my Rasbian Stretch Raspberry Pi Setup it only produces a black image, as the source seems to be black.

  I compiled OpenCV (3.4.1) myself with this great article : https://www.pyimagesearch.com/2017/09/04/raspbian-stretch-install-opencv-3-python-on-your-raspberry-pi/, and it worked perfectly fine. I am using python3 and a virtualenv.

  I tried adding the ffmpeg package : apt install ffmpeg, to no avail.

  2 ideas

  • I compiled the openCV source without support for mkv/mp4/similar ? If so, how would I check that and can I just "re-compile" the whole package ?
  • I am missing codecs, where would I be able to check that ?

  The crucial code (I think) is this :

  cap = cv2.VideoCapture(full_path) are there other options that do not break the majority of my code ? I read about skvideo.io from scikit-video but that does not seem to work with my code...

  I am new to python, any hint is appreciated

  // EDIT, I think it is not a duplicate because I pass the I get no error that the capture cannot be opened and :

  OpenCV FFMPEG support :

  • python -c "import cv2; print(cv2.getBuildInformation())" | grep -i ffmpeg
    • returns : FFMPEG: YES

  FFMPEG Codec :

  • ffmpeg -codecs | grep -i avc (file is using AVC)
    • returns : DEV.LS h264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (decoders: h264 h264_mmal h264_vdpau ) (encoders: libx264 libx264rgb h264_omx h264_vaapi )

  File PATH

  It exists and the path is correct...

  Any other ideas ? Could it possibly the virtualenv ?

  //EDIT2

  Tried with an AVI file

  works...