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• Output video segments via a pipe using FFmpeg

  6 janvier 2019, par Joey Morani

  My Node.js app uses FFmpeg to capture video of a DirectShow device and then output segments for live streaming (HLS). At the moment I’m outputting the segments to files, however if I could output them via a pipe it would allow me to efficiently send the segment via a websocket instead of hosting a HTTP server.

  I’ve tried using this command :

  ffmpeg -y -f dshow -i video=FFsource:audio=Stereo Mix (Realtek High
  Definition Audio) -vcodec libvpx -acodec libvorbis -threads 0 -b:v
  3300k -cpu-used 5 -keyint_min 150 -g 150 -map 0 -flags:v
  +global_header -f segment -

  However it gives the error "Could not write header for output file #0 (incorrect codec parameters ?) : Muxer not found". This commands works for outputting to files (by replacing ’-’ with ’seg_%03d.webm’).

  Does FFmpeg not support pipes for segmented video, or is there something wrong with the command ? Thanks.

• Using ffmpeg to pipe Logitech C920 video to two outputs : re-encoded to RTMP stream and hardware-encoded to file

  18 décembre 2018, par Maros Hluska

  I’m trying to use ffmpeg to accept video from a Logitech C920 and broadcast it to an RTMP stream (e.g. Twitch). But there’s a twist : I would like to also save to file the original 1080p hardware-encoded video.

  So I would like to do both of these :

  1. Re-encode the input to 852x480 resolution and upload to an RTMP url with 1500 bitrate
  2. Save the original input to a file without re-encoding (C920 does hardware encoding with the h.264 codec)

  I’ve tried saving the video to file without re-encoding using the following :

  ffmpeg -s 1920x1080 -framerate 30 -pixel_format uyvy422 -vcodec h264 -f avfoundation -i 'HD Pro' -copyinkf -vcodec copy out.mp4

  This seems to almost work. The webcam light turns on and a few seconds of running this produces a massive file (1GB or so). However, I can’t seem to open the file with VLC. I do see a warning from ffmpeg :

  [AVBSFContext @ 0x7fbd4fc3e9c0] No start code is found.
  
  HD Pro: could not find codec parameters

  I’m on a Mac using ffmpeg 4.1.

  Edit :

  It seems the file that ffmpeg produces is not h264 encoded but rather raw pixel data. I’m starting to think that it’s not possible to set the webcam into the h264 mode with Mac (most other cases do it in Linux with v4l2).

  To anyone answering the question, I’d be happy with a solution that involves Linux as well. Especially if I can use a bootable live USB.

• avformat : add gif pipe demuxer

  8 décembre 2018, par Paul B Mahol

  avformat : add gif pipe demuxer
  

  • [DH] libavformat/Makefile
  • [DH] libavformat/allformats.c
  • [DH] libavformat/img2dec.c
  • [DH] libavformat/version.h