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• Using ffmpeg, the function av_find_input_format("avfoundation") return null

  28 avril 2019, par guojing

  I run this code in iPad mini 4 (Model A1538), iOS 11.2.6

  Try to record audio by FFmpeg.

  av_register_all();
  
  avcodec_register_all();
  
  avdevice_register_all();
  
  
  
  AVFormatContext *pFormatCtx = avformat_alloc_context();
  
  AVDictionary* options = NULL;
  
  av_dict_set(&options,"list_devices","true",0);
  
  AVInputFormat *iformat = av_find_input_format("avfoundation");
  
  printf("==AVFoundation Device Info===\n");
  
  avformat_open_input(&pFormatCtx,"",iformat,&options);
  
  printf("=============================\n");
  
  
  
  if(avformat_open_input(&pFormatCtx,"0",iformat,NULL)!=0){
  
      printf("Couldn't open input stream.\n");
  
      return;
  
  }

  pFormatCtx = NULL, and iformat = NULL.

  Why should this happen, did I missed anything to set ?

• RTSP Streaming on Jetson Xavier NX, Ubuntu 20.04 [closed]

  12 décembre 2023, par Jan

  i am working on a project, where i want to create a rtsp live server from a USB Camera.
To do that i downloaded the mediamtx rtsp server.

  


  Then i am pushing the stream from the camera to the rtsp server, and display it using ffplay, or OpenCV in C++.

  


  This is working, however i get a very low quality, and a delay of up to 1 second.

  


  Is there any way to improve the delay ? If possible i would like to have the same quality and delay as if i read it with gst-launch-1.0.

  


  The command for ffmpeg was

  


  ffmpeg -i /dev/video0 -s 1280x720 -vsync 0 - f rtsp rtsp://localhost:8554/mystream


  


  I also tried to utilize the hardware acceleration with cuda

  


  ffmpeg -i /dev/video0 -s 1280x720 -vsync 0 -hwaccel cuda -hwaccel_output_format cuda -f x11grab -fflags nobuffer -i :0.0+0.0 -preset ultrafast -vcodec libx264 - tune zerolatency -g 1 -omit_video_pes_length 0 - f rtsp rtsp://localhost:8554/mystream


  


  With this I get a better quality, but the delay is still very bad.

  


  Any ideas on how to get a live stream with < 100ms ?&#xA;Did I maybe miss out some additional parameters for ffmpeg that resolve that problem ?

  &#xA;

• Ffmpeg 2 Input cameras in single ouput

  1er juin 2020, par Expressingx

  I have app where it streams from a camera to a file with Preview using liabv. &#xA;Now there is requirement to be able to stream from 2 cameras simultaneously and output to a single file. The Preview will be like a CCTV camera and written to single output. Is this possible with libav ?&#xA;Before doing anything I've tried with ffmpeg.exe directly and found this :

  &#xA;&#xA;

  ffmpeg -f dshow -i video="Camera1" -i video="Camera2" -filter_complex "nullsrc=size=640x480 [base];[0:v] setpts=PTS-STARTPTS, scale=640x480 [upperleft];[1:v] setpts=PTS-STARTPTS, scale=640x480 [upperright];[base][upperleft] overlay=shortest=1 [tmp1];[tmp1][upperright] overlay=shortest=1:x=640:y=480 [tmp2];"-c:v libx264 output.mp4


  &#xA;&#xA;

  But every time throws error 'No such file or directory' for the second camera, while I've verified the camera is working if I use it as single input. Do I miss something ?

  &#xA;&#xA;

  Overall is it possible to achieve that ?

  &#xA;