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• Revision 23b5c58174 : Set scaled image format correctly Change-Id : Ic4ced4208375ca31f8adb73a5ee9ddd7d

  23 août 2014, par Deb Mukherjee

  Changed Paths :
   Modify /vpxdec.c

  
  
  Set scaled image format correctly

  Change-Id : Ic4ced4208375ca31f8adb73a5ee9ddd7da50dfac

• Convert HEVC/H.265 video to a more widely supported format using fluent-ffmpeg in Node.js

  21 juin 2021, par Daniel Loiterton

  My app allows users to upload videos from their phones. However, the latest iPhone default format (HEVC / H.265) does not seem to be supported by Chrome and other browsers, so some users cannot stream the videos.

  


  I'm already using fluent-ffmpeg on my Node.js backend to read metadata and extract thumbnails from the uploaded videos. How would I go about converting HEVC videos to something else ? What format/options would be appropriate for streaming to browsers ? Ideally I'd like to keep files fairly small, and I'm willing to sacrifice some quality to that end.

  


• What is the GLFW screen format for ffmpeg encoding ?

  3 septembre 2022, par Turgut

  I have a program where I have a GLFW window and read that window using glReadPixels(0, 0,window_width, window_height, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*) Buffer); then use that Buffer to encode a frame via ffmpeg. It works fine however the resolution is a bit low.

  


  I tried changing bit-rates to no avail so I started experimenting with formats. Normally I'm using AV_PIX_FMT_YUV420P in my encoder as my format since the data that comes from the glfw window is RGBA but this format result in the said low resolution video. The result video is a lot more pixelated than whats seen on the GLFW window.

  


  What could be the optimal pixel format for reading GLFW window ? Some formats straight up not work resulting in Specified pixel format  yuyv422 is invalid or not supported error.

  


  And here is where I got that error from :

  


  ret = avcodec_open2(c, codec, &opt);


  


  This line causes me to get Specified pixel format  yuyv422 is invalid or not supported error when I use something other than YUV420.

  


  I also have this setting #define SCALE_FLAGS SWS_BICUBIC which im not sure what it does but may also cause my error. (Not likeliy since this comes after the line mentioned above, but I could just keep the format at YUV420 and change SWS_BICUBIC instead.)

  


  I'm using ubuntu, ffmpeg, glfw and glad (GLSL) to render the texture writeen in the frames. I got the encoder from ffmpegs muxing.c example.

  


  Edit : Using AV_PIX_FMT_RGBA also results in a similar error.

  


  Edit : Here is my sample code where I convert Buffer to ffmepg format :

  


  #define STREAM_PIX_FMT AV_PIX_FMT_YUV420P
...
void video_encoder::set_frame_yuv_from_rgb(AVFrame *frame, struct SwsContext *sws_context) {
    const int in_linesize[1] = { 4 * width };

    sws_context = sws_getContext(
            width, height, AV_PIX_FMT_RGBA,
            width, height, STREAM_PIX_FMT,
            SWS_BICUBIC, 0, 0, 0);

    sws_scale(sws_context, (const uint8_t * const *)&rgb_data, in_linesize, 0,
            height, frame->data, frame->linesize);
}