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• How to get DirectShow device list with ffmpeg in c++ ?

  24 août 2018, par fyo

  I’m trying to get dshow device list with ffmpeg. I cannot get it but ffmpeg gets it by its own. Here is the code. It returns AVERROR(ENOSYS) for avdevice_list_input_sources. But avformat_open_input prints all devices. How can I get dshow devices and options in c++ code.

      avdevice_register_all();
  
      AVInputFormat *iformat = av_find_input_format("dshow");
  
      printf("========Device Info=============\n");
  
      AVDeviceInfoList *device_list = NULL;
  
      AVDictionary* options = NULL;
  
      //av_dict_set(&options, "list_devices", "true", 0);
  
      int result = avdevice_list_input_sources(iformat, NULL, options, &device_list);
  
  
  
      if (result < 0)
  
          printf("Error Code:%s\n", av_err2str(result));//Returns -40 AVERROR(ENOSYS)
  
      else printf("Devices count:%d\n", result);
  
  
  
      AVFormatContext *pFormatCtx = avformat_alloc_context();
  
      AVDictionary* options2 = NULL;
  
      av_dict_set(&options2, "list_devices", "true", 0);
  
      avformat_open_input(&pFormatCtx, NULL, iformat, &options2);
  
      printf("================================\n");

• Right choice to play audio and video content

  22 juin 2012, par deimus

  What I'm doing :

  I need to play audio and video files that are not supported by Apple on iPhone/iPad for example mkv/mka files which my contain several audio channels.

  I'm using libffmpeg to find audio and video streams in media file.
  Video is being decoded with avcodec_decode_video2 and audio with avcodec_decode_audio3
  the return values are following for each function are following

  • avcodec_decode_video2 - returns AVFrame structure which encapsulates information about the video video frame from the pakcage, specifically is has data field which is a pointer to the picture/channel planes.
  • avcodec_decode_audio3 - returns samples of type int16_t * which I guess is the raw audio data

  So basically I've done all this and successfully decoding the media content.

  What I have to do :
  I've to play the audio and video accordingly using Apples services. The playback I need to perform should support mixing of audio channels while playing video, i.e. let say mkv file contains two audio channel and a video channel. So I would like to know which service will be the appropriate choice for me ? My research showed that AudioQueue service might be useful audio playback, and probably AVFoundation for video.

  Please help to find the right technology for my case i.e. video playeback + audio playback with possible audio channel mixing.

• How to interpret ffmpeg -pix_fmts output ?

  11 août 2015, par RichAmberale

  Running ffmpeg -pix_fmts returns a list of formats. Snip :

  IO... yuv444p16be            3            48
  
  ..H.. vdpau_mpeg4            0             0
  
  ..H.. dxva2_vld              0             0
  
  IO... rgb444le               3            12
  
  IO... rgb444be               3            12
  
  IO... bgr444le               3            12

  What do the I O and H on the right side mean ? What are the numbers in the 2 leftmost columns ?