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• Configuration of video device failed, falling back to default

  4 février 2021, par hgwd

  I'm writing a program to open my mac osx's facetime hd camera and get h264 data with ffmpeg, but i encounter encounter a hard problem at the first step.

  


  AVFormatContext *Producer::OpenCamera()
{
    AVFormatContext *pContext = avformat_alloc_context();
    AVInputFormat *infmt = av_find_input_format("avfoundation");
    if (infmt != nullptr)
    {
        AVDictionary *paramDict = nullptr;
        av_dict_set(&paramDict, "video_device_index", "1", 0);
        av_dict_set(&paramDict, "video_size", "1280x720", 0);
        av_dict_set(&paramDict, "framerate", "30", 0);
        av_dict_set(&paramDict, "pixel_format", "yuyv422", 0);

        int ret = avformat_open_input(&pContext, "0", infmt, &paramDict);
        if (ret != 0)
        {
            std::cout << "cannot open input" << std::endl;
            avformat_free_context(pContext);
            return nullptr;
        }
    }

    return pContext;
}


  


  When I call the function, I get the result below :

  


  '' opened
Configuration of video device failed, falling back to default.


  


  Addtionally, when I set av_dict_set(&paramDict, "video_device_index", "0", 0) ; I'll get sig abort, which makes me confused. Can anyone help me ?

  


• ffmpeg scale down video dynamically (squeeze-back) or zoompan out to smaller than original

  27 avril, par Sam

  I have 2 videos, I'm trying to overlay one on top of the other, and have it shrink down in an animated fashion until it appears like a picture-in-picture setup. Then, after a few seconds it should scale back up.

  


  This is what I am trying to achieve (these would be videos, not images) :


  


  This is the closest I've been able to get, but, crucially, zoompanning "out" (as opposed to "in") does not appear to work ; so, of course, this does not work :

  


  ffmpeg -i bg.mov -i top.mov -filter_complex "[0:v]zoompan=z='pzoom-0.1':d=1, setpts=PTS-STARTPTS[top]; [1:v]setpts=PTS-STARTPTS+2/TB, scale=1920x1080, format=yuva420p,colorchannelmixer=aa=1.0[bottom]; [top][bottom]overlay=shortest=0" -vcodec libx264 out.mp4

  


  Is this achievable with ffmpeg ?

  


• avformat/iamfdec : swap back and side streams if both are present

  30 décembre 2024, par James Almer

  avformat/iamfdec : swap back and side streams if both are present
  Layouts with both pairs (7.1, 7.1.2, etc) in IAMF that follow the definition in
  
  ITU-R BS.2051-3 for Systems I and J also follow its ordering. This means side
  
  comes before back, which is the inverse of how it's defined in AVChannel.
  To workaround this without having to use custom order channel layouts, swap the
  
  stream ids in the input IAMF structure, so packets for one are mapped to the
  
  other.
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavformat/iamfdec.c
  • [DH] libavformat/version.h
  • [DH] tests/ref/fate/iamf-7_1_4