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• avformat/movenc : add support for TTML muxing

  15 février 2021, par Jan Ekström

  avformat/movenc : add support for TTML muxing
  Includes basic support for both the ISMV ('dfxp') and MP4 ('stpp')
  
  methods. This initial version also foregoes fragmentation support
  
  in case the built-in sample squashing is to be utilized, as this
  
  eases the initial review.
  Additionally, add basic tests for both muxing modes in MP4.
  Signed-off-by : Jan Ekström <jan.ekstrom@24i.com>
  

  • [DH] libavformat/Makefile
  • [DH] libavformat/isom.h
  • [DH] libavformat/movenc.c
  • [DH] libavformat/movenc.h
  • [DH] libavformat/movenc_ttml.c
  • [DH] libavformat/movenc_ttml.h
  • [DH] tests/fate/subtitles.mak
  • [DH] tests/ref/fate/sub-ttml-mp4-dfxp
  • [DH] tests/ref/fate/sub-ttml-mp4-stpp

• avcodec/libaomenc : use ctx->usage to get default cfg

  14 août 2021, par James Zern

  avcodec/libaomenc : use ctx->usage to get default cfg
  this prevents some mismatches in config values for realtime and all
  
  intra modes, avoiding failures like :
  [libaom-av1 @ ...] Failed to initialize encoder : Invalid parameter
  
  [libaom-av1 @ ...]   Additional information : g_lag_in_frames out of
  
  range [..0]
  Signed-off-by : James Zern <jzern@google.com>
  

  • [DH] libavcodec/libaomenc.c
  • [DH] libavcodec/version.h

• Transition between FFMpeg streams

  25 juillet 2021, par spectacularbob

  I have been running a Youtube livestream for a while and I am developing a solution so that I can run the stream remotely through a browser. My plan is to have an ASP.net core web api project running a background service that when I send the streaming information to it, it launches FFMpeg to stream a USB webcam. I also need to be able to press a button to "mute" the stream so it shows a blank video with some text overlay (i.e. "Technical Difficulties").

  


  My solution so far is to use two instances of FFMpeg. When I switch modes, I kill one process and start the other one. I have gotten it working somewhat, but when I switch back and forth between "mute mode" and "streaming mode", Youtube seems to choke on the stream being changed. I suspect it's because when I go from mute mode back to stream mode, youtube doesn't recognize that the mute mode has ended. Also, mute mode displays the text like I want, but it causes the Youtube player to stop being "live" so that if I do get the regular stream going again, the user has to click the "Live" button to be up to date.

  


  Here's the command line for both modes :

  


  Stream Mode :

  


  ffmpeg.exe -f dshow -i video="<webcam>" -f dshow -i audio="<microphone>" -vcodec libx264 -pix_fmt yuv420p -preset veryfast -r 30 -g 60 -b:v 3500k -f flv rtmp://a.rtmp.youtube.com/live2/<stream key="key">&#xA;</stream></microphone></webcam>

  


  Mute Mode (blank.mp4 is a 3 second long blank video) :

  


  ffmpeg.exe -stream_loop -1 -i ./FFMpeg/blankvid.mp4 -vf "drawtext=fontfile=C\\\\:/Windows/Fonts/Arial.ttf:text=&#x27;Technical Difficulties&#x27;:fontcolor=white:fontsize=60:box=1:boxcolor=black@0.5:boxborderw=5:x=(w-text_w)/2:y=(h-text_h)/2" -vcodec libx264 -pix_fmt yuv420p -preset veryfast -r 30 -g 60 -b:v 3500k -f flv -flvflags no_duration_filesize rtmp://a.rtmp.youtube.com/live2/<stream key="key">&#xA;</stream>

  


  Last note : I know that there may be a way using a color filter to create the black video, rather than having a blankvid.mp4. If you also know how to get the parameters for that, it would be very helpful.