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• How to keep the last 1 min video streaming using ffmpeg ?

  4 août 2020, par Lawrence song

  I have a UVC camera /dev/video1. The Camera will be always on. but I only care about the last 1 min data stream.

  


  after searching online I got a ffmpeg cmd :

  


  ./ffmpeg -f v4l2 -input_format mjpeg -video_size 320x240 -i /dev/video1 -c copy -f segment -segment_time 60 -segment_wrap 2 output.mkv


  


  However I got a error and here is the result

  


    libavutil      56. 56.100 / 56. 56.100
  libavcodec     58. 97.100 / 58. 97.100
  libavformat    58. 49.100 / 58. 49.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
Input #0, matroska,webm, from '/sdcard/Movies/output.mkv':
  Metadata:
    ENCODER         : Lavf58.49.100
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: mjpeg (Baseline), yuvj422p(pc, bt470bg/unknown/unknown), 320x240, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
[matroska @ 0x3899e10] Invalid segment filename template 'output.mkv'
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument


  


• Debayer video with ffmpeg

  23 février 2023, par Andrew Spence

  Looking to debayer video with ffmpeg. I can't find a way to do it without piping raw video between two instances of ffmpeg, because I can't change the pixel format of my input video "in place" from gray to bayer_gbrg8. So, this command works :

  


  ffmpeg -i fr_losslessmovie_png_codec.avi -f image2pipe -pix_fmt gray \
-vcodec rawvideo - | ffmpeg -r 25 -f rawvideo -s 2048x700 \
-pix_fmt bayer_gbrg8 -i pipe:0 -y -pix_fmt yuv420p -b:v 25000k \
fr_debayer_compressed.mp4


  


  I would have given the source movie this pixel format, but didn't realize ffmpeg suported bayered pixel formatting.

  


  Didn't see this exact question online, and have not found a way to change the pixel format with video filters etc. without ffmpeg thinking i'm trying to convert the data. I just want to change the pixel format that the already existing gray data has been assigned.

  


  Thanks in advance !

  


• Pass ID3D11Texture2D back buffer to libx264 encoder

  17 janvier 2019, par Chris Sixsmith

  I’m writing a C++ program to encode frames from a DirectX game to the H.264/MPEG-4 AVC format. I am using libx264 alone with no other dependencies at the moment.

  I have a ID3D11Texture2D* resolved back buffer of the next game frame. I need to somehow copy this into the x264_picture input (apparently YUV420P format according to limited help I’ve found) but I cannot find any way to do so online.

  Here is my code at the moment :

  void Fx264VideoEncoder::Fx264VideoEncoderImpl::InitFrameInputBuffer(const FTexture2DRHIRef& BackBuffer, FFrame& Frame)
  
  {
  
      x264_picture_alloc(Frame.InputPicture, X264_CSP_I420, x264Parameters.i_width, x264Parameters.i_height);
  
  
  
      // We need to take the back buffer and convert it to an input format that libx264 can understand
  
      {
  
          ID3D11Texture2D* ResolvedBackBufferDX11 = (ID3D11Texture2D*)(GetD3D11TextureFromRHITexture(Frame.ResolvedBackBuffer)->GetResource());
  
          EPixelFormat PixelFormat = Frame.ResolvedBackBuffer->GetFormat();
  
  
  
          // ...?
  
      }
  
  }