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• C++ ffmpeg sws_getCachedContext seg fault when reading opengl buffer

  3 juillet 2022, par user19068953

  I made a program that draws some stuff on opengl, then reads the frames on the screen as rgba and encodes it as a yuv420 video, but I get a segfault when I try to send the red opengl frame to sws_getCachedContext. I used the muxing.c as the encoder and my code is as follows (I used align 256 because i have another framebuffer that uses 128) :

  


      constexpr int ALIGNMENT = 256;
    if (posix_memalign((void**)&state.glBuffer, ALIGNMENT, gl_width * gl_height * 4) != 0) 
    {
        VI_ERROR("Couldn't allocate frame buffer ");
        return false;
    }
    REGISTER("done, returning");
    return true;


  


  Then i read the frame after drawing the stuff i want :

  


          glReadPixels(0, 0,
                 gl_width, gl_height, 
                 GL_RGBA, GL_UNSIGNED_BYTE, 
                 (GLvoid*) state.glBuffer);


  


  The window is the same size as the gl_buffer (I know the result will be flipped, thats ok)

  


  And finally i send it to the encoder(rgb_data is glBuffer) :

  


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

width = gl_width;
height = gl_height;
sws_context = sws_getCachedContext(sws_context,
        width, height, AV_PIX_FMT_RGBA,
        width, height, AV_PIX_FMT_YUV420P,
        0, 0, 0, 0);
        
sws_scale(sws_context, (const uint8_t * const *)&rgb_data, in_linesize, 0,
        height, frame->data, frame->linesize);
}


  


  I get a seg fault on sws_getCachedContext any idea why this happens and how do i fix it ?

  


  Edit : width = 512, height = 256, valgrind says : Invalid read of size 16.

  


• Podcast Producer 2 : Where I’m at

  27 août 2009

  If all of this scheduled publishing stuff has worked, you’ll find a handful of posts about Podcast Producer 2 below.

  I just took all of the notes I’ve collected while working on a PCP2 project over the last month or so, and wrote them up. It’s entirely possible that there are all sorts of things I’m missing, or misunderstanding. Now that the NDA is expired, hopefully some more folks will go public with their own discoveries.

  So, if you’re coming across these posts and you know things I don’t about this strange world of ruby and media, please let me know in the commments !

• CEFSharp proprietary codecs support

  8 mars 2015, par Citrus

  I got an issue with CEFSharp which is chromium embeddable framework wrapper for C#.NET. I need to make proprietary codecs available for a project (H.264/MP4 to be specific). After some google-fu I’ve found that I must set the use_proprietary_codecs to true in the cef.gyp(i) file, but the problem is, that I’ve got this stuff from NuGet and there aren’t any cef.gyp(i) files. I need this library badly to have the codec support, else we must rewrite 5 months of work completely, which isn’t clearly an option. Thanks for any help !