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• How to label outputs inside the ffmpeg's process of transcoding for use them in mapping and in tee muxer ?

  20 juillet 2022, par youni

  I have a video, that consists of video stream and audio stream. I trancode it into two videos : 1920x1080 and 1280x720 with the same audio stream. I do not wish to transcode audio stream two times, I wish to use it twice with ffmpeg '-f tee' option. Now I need your support.

  


  This does not work :

  


  ffmpeg -to 00:00:10 -i /v \
  -map 0:v -an -vcodec libx264 -s 1920x1080 -b:v 4000k [VIDEO]\
  -map 0:v -an -vcodec libx264 -s 1280x720 -b:v 2000k [VIDEO2]\
  -f tee \
    -map [VIDEO] -map [VIDEO2] -map 0:a \
      -c:a mp3 -ab 42k \
        "[select='0,2':f=flv]1.mp4|[select='1,2':f=flv]2.mp4"
[NULL @ 0x55b7e2709340] Unable to find a suitable output format for '[VIDEO]'
[VIDEO]: Invalid argument


  


  My logic here was to label each output after -vcodec.. options and use these two labels in mapping and in tee muxer. Could you, please, advise what to do here ?

  


  This also does not work :

  


  ffmpeg -to 00:00:10 -i /v \
  -c:a mp3 -ab 42k \
    -filter_complex '[0:a]acopy[AUDIO];[0:a]acopy[AUDIO2]' \
  -map v -map [AUDIO] -vcodec libx264 -s 1920x1080 -b:v 4000k -f flv 1.mp4 \
  -map v -map [AUDIO2] -vcodec libx264 -s 1280x720 -b:v 2000k -f flv 2.mp4
ffprobe 1.mp4
ffprobe 2.mp4
  1.mp4: Stream #0:1: Audio: mp3, 48000 Hz, stereo, fltp, 42 kb/s
  2.mp4: Stream #0:1: Audio: mp3, 48000 Hz, stereo, fltp, 128 kb/s


  


  The result file 2.mp4 has default audio settings : 128 kb/s instead of 42 kb/s.

  


  My workable variant gives exactly correct result, but the process of transcoding is not optimized :

  


  ffmpeg -to 00:00:10 -i /v \
  -c:a mp3 -ab 42k -vcodec libx264 -s 1920x1080 -b:v 4000k -f flv 1.mp4 \
  -c:a mp3 -ab 42k -vcodec libx264 -s 1280x720 -b:v 2000k -f flv 2.mp4


  


  In this process ffmpeg transcodes audio stream twice, as I think. But I need to optimize this process and transcode audio stream once and use it twice with tee muxer. Could you say me, how to label outputs correctly as in my first code for use them in -map ?

  


• Revision 593fe475bd : Removed support for the Autotools build system.

  21 juillet 2012, par Marc Noirot

  Changed Paths :
   Delete /Makefile.am

  
   Delete /autogen.sh

  
   Delete /configure.ac

  
   Delete /man/Makefile.am

  
   Delete /schemas/Makefile.am

  
   Delete /src/Makefile.am

  
   Delete /src/libyaml/Makefile.am

  
   Delete /tests/Makefile.am

  
  
  Removed support for the Autotools build system.

• ffmpeg change inputs / mapping while recording

  20 avril 2020, par Suuuehgi

  I have a rtsp video-source stream1 and an audio source I currently merge and send to a rtmp-server using :

  



  stream1="rtsp://streamurl1"

/usr/bin/ffmpeg                    \
    [...]
    -i "$stream1"                  \
    [...]
    -itsoffset $AUDIOVIDEOOFFSET   \
    -f pulse                       \
    -i default                     \
    [...]
    -vcodec copy                   \
    -map 0:v -map 1:a              \
    [...]
    -f flv "rtmp://streamingserver"


  



  


  I would now like to add a second video source stream2 and switch between stream1 and stream2 back and forth without interrupting the audio. Both streams are identical / come from identical cameras.

  


  



  Is there any sane way to do this with ffmpeg ? Or how would you recommend doing it ?

  



  Just stopping the process and restarting it using stream2 instead of stream1 works but results in several seconds outage on the stream and is the current worst case scenario I would like to improve.