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• FFmpeg capture, mkvtimestamp_v2 and timecode don't play nice

  24 mai 2021, par Bouke

  Trying to capture and modify the TC in-file afterwards.
I've found a nice way to store the timestamps from the capture.
Gyan's brillant filterchain

  


  This works fine using this line :

  


  ffmpeg -hide_banner -f "decklink" -queue_size "1073741824" -raw_format "auto" -format_code "Hi50" -video_input "sdi" -i "bm mini One" -filter_complex "settb=1/1000,setpts=RTCTIME/1000-1500000000000,mpdecimate,split[out][ts];[out]setpts=N/25/TB[out]" -map "[out]" -c:a "copy" -c:v "prores" -profile:v "1" -vendor "ap10" -pix_fmt "yuv422p10le" "/Volumes/Data/tst1.mov" -map "[ts]" -f mkvtimestamp_v2 "/Volumes/Data/time.txt" -vsync 0


  


  But, when I add -timecode "00:00:00:00" (to force a TC atom in the output), horrible things happen.

  


  ffmpeg -f "decklink" -queue_size "1073741824" -raw_format "auto" -format_code "Hi50" -video_input "sdi" -i "bm mini One" -filter_complex "settb=1/1000,setpts=RTCTIME/1000-1500000000000,mpdecimate,split[out][ts];[out]setpts=N/25/TB[out]" -map "[out]" -timecode "00:01:00:00" -c:a "copy" -c:v "prores" -profile:v "1" -vendor "ap10" -pix_fmt "yuv422p10le" "/Volumes/Data/tst1.mov" -map "[ts]" -f mkvtimestamp_v2 "/Volumes/Data/time.txt" -vsync 0


  


  The timecode does not run at the video speed, skips a frame or two here and there, and the image freezes after a random amount of time (between 10 seconds and a minute or so).

  


  How come the timecode can mess up stuff that much ? From what I understand it's just a couple of atoms in the moov atom, and a reference where the actual TC value (as frames) is stored in the mdat.

  


  I highly suspect the -vsync 0 to also work on the video, and I've had issues with that before. If I omit that, the video is fine, the TC is fine, but there is no metadata output, just the # timecode format v2

  


• SRT protocol not found - Raspbery Pi 4 via ffmpeg

  12 août 2021, par Tim Martin

  We tried to stream from a rasp Pi 4 via SRT, but we got a error : "protocol not found". Our command line is :

  


  ffplay srt://127.0.0.1:9500?mode=listener&latency=20000


  


  We tried the following guides :
https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu
how to compile ffmpeg with enabling libsrt
https://www.undergroundnews.dk/index.php/item/107-rtmp-eller-srt-streaming

  


  Those guides worked so far and compiled but we still got the error message.

  


  Do you have any ideas how to get the srt protocol working on a pi via ffmpeg ?

  


• FFmpeg with multiple output streams

  22 novembre 2018, par William Blake

  I am using ffmpeg to combine an rtsp stream with an audio stream from a usb mic. I would like to stream the combined audio and and video to an RTMP stream and just the audio to an icecast stream simultaneously. I have them working separately but am having difficulty finding the magic combination using the -f tee parameter. It seems like that would be the best way. This was the reference I was trying to use : https://trac.ffmpeg.org/wiki/Creating%20multiple%20outputs

  Here are the separate commands :

  ffmpeg -rtsp_transport tcp -use_wallclock_as_timestamps 1 -thread_queue_size 1024  \
  
  -i "rtsp://RTSP-SERVER-ADDRESS" \
  
  -f alsa -thread_queue_size 1024 -ac 1 -itsoffset 00:00:01.2 -i hw:1,0 \
  
  -vcodec copy -acodec mp3 -ar 44100 -ab 32k -map 0:v -map 1:a -bufsize 12000k \
  
  -f flv 'RTMP-SERVER-ADDRESS'
  
  
  
  ffmpeg -ac 1 -f alsa -i hw:1,0 -acodec mp3 -ab 32k -ac 1 -content_type audio/mpeg -f mp3 icecast://ICECAST-ADDRESS

  However my attempts to combine them have been futile. Any thoughts ?