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• Basic "pass-through" use of FFmpegReader/FFmpegWriter in scikit-video

  6 février 2021, par JonathanZ supports MonicaC

  I am starting to use scikit-video and am having trouble writing files. I have reduced the problem to the simplest possible example

  


  vid_file = "6710185719062326259_stamp_25pct.mp4"
output_file = "out_temp3.mp4"
reader = skvideo.io.FFmpegReader(vid_file)
writer = skvideo.io.FFmpegWriter(output_file)
for frame in reader.nextFrame():
        writer.writeFrame(frame)
writer.close()


  


  I'm playing the files in VLC, and the vid_file is valid but the output file, though playable, is mostly big green blocks (though I can discern some details from the original video in it).

  


  My goal, or course, is to do "interesting" manipulations of the frame before I write it out, but I need to get the "no modifications" version working correctly first. I'm also going to be using this on large files, so the vread/vwrite functions that process an entire file at once are not appropriate.

  


  I'm guessing I need to set the appropriate values in the outputdict parameter for the FFmpegWriter, but there are so many that I don't know where to start. I have tried

  


  writer = skvideo.io.FFmpegWriter(output_file, outputdict={'-crf': '0', '-pix_fmt': 'rgb24'})


  


  (-crf 0 to suppress any compression, -pixfmt rgb24 as that's what FFmpegReader says it delivers by default, but these don't work either.

  


  Any ideas on how to make this work ?

  


  Here's the skvideo.io.ffprobe video information for the input file.

  


  {
    "@index": "0",
    "@codec_name": "h264",
    "@codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
    "@profile": "High",
    "@codec_type": "video",
    "@codec_time_base": "1/30",
    "@codec_tag_string": "avc1",
    "@codec_tag": "0x31637661",
    "@width": "480",
    "@height": "270",
    "@coded_width": "480",
    "@coded_height": "272",
    "@has_b_frames": "2",
    "@pix_fmt": "yuv420p",
    "@level": "21",
    "@chroma_location": "left",
    "@refs": "1",
    "@is_avc": "true",
    "@nal_length_size": "4",
    "@r_frame_rate": "15/1",
    "@avg_frame_rate": "15/1",
    "@time_base": "1/15360",
    "@start_pts": "0",
    "@start_time": "0.000000",
    "@duration_ts": "122880",
    "@duration": "8.000000",
    "@bit_rate": "183806",
    "@bits_per_raw_sample": "8",
    "@nb_frames": "120",
    "disposition": {
        "@default": "1",
        "@dub": "0",
        "@original": "0",
        "@comment": "0",
        "@lyrics": "0",
        "@karaoke": "0",
        "@forced": "0",
        "@hearing_impaired": "0",
        "@visual_impaired": "0",
        "@clean_effects": "0",
        "@attached_pic": "0",
        "@timed_thumbnails": "0"
    },
    "tag": [
        {
            "@key": "language",
            "@value": "und"
        },
        {
            "@key": "handler_name",
            "@value": "VideoHandler"
        }
    ]
}


  


  I will mention that when I ffprobe the output file the only differences I see are 1) the timing data is different, which isn't surprising, and 2) the output file has

  


      "@has_b_frames": "0",
    "@pix_fmt": "yuv444p",


  


  I'm pretty confident the reader is working okay, because if I write out the data with

  


  skimage.io.imsave('x.png', frame,  check_contrast=False)


  


  it looks good.

  


• I am trying to use ffmpeg to separate audio from video, but after downloading the ffmpeg build I cannot seem to activate it in Power Shell [duplicate]

  19 janvier 2021, par Row Boater

  Ok, look y'all, I am NOT an aspiring programmer. I'm simply trying to separate audio from video of a youtube video I downloaded.

  


  What I've done :

  


  Downloaded YT vid using 4k video Downloader

  


  I downloaded ffmpeg build from https://ffmpeg.org/download.html#build-windows

  


  I downloaded WinZip in order to access the ffmpeg files.

  


  I thought I used winzip correctly, but whenever I paste the command code line recommended to me, ffmpeg -i video.mp4 -c:a pcm_s16le audio.wav, I receive the following :

  


  


  PS C :\Users\user\Videos\4K Video Downloader> ffmpeg -i video.mp4 -c:a
pcm_s16le audio.wav ffmpeg : The term 'ffmpeg' is not recognized as
the name of a cmdlet, function, script file, or operable program.
Check the spelling of the name, or if a path was included, verify that
the path is correct and try again. At line:1 char:1

  


  

  • ffmpeg -i video.mp4 -c:a pcm_s16le audio.wav

  


  • 


      + CategoryInfo          : ObjectNotFound: (ffmpeg:String) [], CommandNotFoundException
  + FullyQualifiedErrorId : CommandNotFoundException



    


  


  


  PS C :\Users\user\Videos\4K Video Downloader>

  


  


  This is all Phoenician to me, but what I take away is that I have not completed some step to fully incorporate the ffmpeg code into my system. I believe that I am not using Winzip correctly.

  


  Thanks for your time.

  


• Copy ffmpeg d3dva texture resource to shared rendering texture

  10 juin 2020, par Teamol

  I'm using ffmpeg to decode video via d3dva based on this example https://github.com/FFmpeg/FFmpeg/blob/master/doc/examples/hw_decode.c. I'm able to succesfully decode video. What I need to do next is to render decoded NV12 frame. I have created directx rendering texture based on this example https://github.com/balapradeepswork/D3D11NV12Rendering and set it as shared.

  



      D3D11_TEXTURE2D_DESC texDesc;
    texDesc.Format = DXGI_FORMAT_NV12;              // Pixel format
    texDesc.Width = width;                          // Width of the video frames
    texDesc.Height = height;                        // Height of the video frames
    texDesc.ArraySize = 1;                          // Number of textures in the array
    texDesc.MipLevels = 1;                          // Number of miplevels in each texture
    texDesc.BindFlags = D3D11_BIND_SHADER_RESOURCE; // We read from this texture in the shader
    texDesc.Usage = D3D11_USAGE_DEFAULT;
    texDesc.MiscFlags = D3D11_RESOURCE_MISC_SHARED;
    texDesc.CPUAccessFlags = 0;

    hr = device.CreateTexture2D(&texDesc, null, &nv12Texture);
    if (FAILED(hr))
    {
        error("Failed to create NV12 texture (hr: %s)", hr);
        return false;
    }

    // QI IDXGIResource interface to synchronized shared surface.
    IDXGIResource dxgiResource;
    nv12Texture.QueryInterface(&IID_IDXGIResource, cast(void**)&dxgiResource);

    // obtain handle to IDXGIResource object.
    hr = dxgiResource.GetSharedHandle(&sharedHandle);
    dxgiResource.Release();
    dxgiResource = null;

    if (FAILED(hr))
    {
        error("Failed to create NV12 texture shared handle (hr: %s)", hr);
        return false;
    }


  



  I'm then trying to copy nv12 from ffmpeg texture to my rendering texture. exactly as ffmpeg does in function d3d11va_transfer_data.

  



      ID3D11Texture2D hwTexture = cast(ID3D11Texture2D)frame.data[0];

    ID3D11Device hwDevice;
    hwTexture.GetDevice(&hwDevice);

    ID3D11DeviceContext hwDeviceCtx;
    hwDevice.GetImmediateContext(&hwDeviceCtx);

    ID3D11Texture2D sharedTexture;

    HRESULT hr = device.OpenSharedResource(sharedHandle, &IID_ID3D11Texture2D,cast(void**) &sharedTexture);
    if(FAILED(hr))
    {
        error("Failed to obtaion open shared resource.");
        return;
    }

    int index = cast(int)frame.data[1];
    hwDeviceCtx.CopySubresourceRegion(sharedTexture, 0, 0, 0, 0, hwTexture, index, null);


  



  But the rendering window is just green no error no FAILED hr result nothing. I'm able render frames when I'm using sw decoder I just create texture with D3D11_USAGE_DYNAMIC and D3D11_CPU_ACCESS_WRITE.

  



  Here us desc of each texture.

  



  hwTexture desc D3D11_TEXTURE2D_DESC(1280, 720, 1, 20, 103, DXGI_SAMPLE_DESC(1, 0), 0, 512, 0, 0)
nv12Texture desc D3D11_TEXTURE2D_DESC(1280, 720, 1, 1, 103, DXGI_SAMPLE_DESC(1, 0), 0, 8, 0, 2)
sharedTexture desc D3D11_TEXTURE2D_DESC(1280, 720, 1, 1, 103, DXGI_SAMPLE_DESC(1, 0), 0, 8, 0, 2)


  



  Any idea what I'm missing ?