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• How to synchronize HLS and/or MPEG-DASH videos on multiple clients using ExoPlayer ?

  22 mai 2019, par G C

  I’m trying to guarantee synchronization between multiple clients using DASH and/or HLS. Synchronization between each client must fall within 40 milliseconds.

  Live streaming seems to be an obvious choice. However, the only way to really get within a small time frame of synchronization would be to lower the segment times. Is this the only viable solution ? Are there any tags that would help me keep clients within 40 milliseconds to the live time ?

  Currently, I’m using FFMPEG to encode video and audio to live content.

• How to generate valid live DASH for YouTube ?

  24 septembre 2019, par Matt Hensley

  I am attempting to implement YouTube live video ingestion via DASH as documented at :
  https://developers.google.com/youtube/v3/live/guides/encoding-with-dash

  To start, I am exercising the YouTube API manually and running ffmpeg to verify required video parameters before implementing in my app.

  Created a new livestream with liveStreams.insert and these values for the cdn field :

  "cdn": {
  
      "frameRate": "variable",
  
      "ingestionType": "dash",
  
      "resolution": "variable"
  
  }

  Created a broadcast via liveBroadcasts.insert, then used liveBroadcasts.bind to bind the stream to the broadcast.

  Then I grabbed the ingestionInfo from the stream and ran this ffmpeg command, copying in the ingestionAddress with the streamName :

  ffmpeg -stream_loop -1 -re -i mov_bbb.mp4 \
  
      -loglevel warning \
  
      -r 30 \
  
      -g 60 \
  
      -keyint_min 60 \
  
      -force_key_frames "expr:eq(mod(n,60),0)" \
  
      -quality realtime \
  
      -map v:0 \
  
      -c:v libx264 \
  
      -b:v:0 800k \
  
      -map a:0 \
  
      -c:a aac \
  
      -b:a 128k \
  
      -strict -2 \
  
      -f dash \
  
      -streaming 1 \
  
      -seg_duration 2 \
  
      -use_timeline 0 \
  
      -use_template 1 \
  
      -window_size 5 \
  
      -extra_window_size 10 \
  
      -index_correction 1 \
  
      -adaptation_sets "id=0,streams=v id=1,streams=a" \
  
      -dash_segment_type mp4 \
  
      -method PUT \
  
      -http_persistent 1 \
  
      -init_seg_name "dash_upload?cid=${streamName}&copy=0&file=init$RepresentationID$.mp4" \
  
      -media_seg_name "dash_upload?cid=${streamName}&copy=0&file=media$RepresentationID$$Number$.mp4" \
  
      'https://a.upload.youtube.com/dash_upload?cid=${streamName}&copy=0&file=dash.mpd'

  It appears all the playlist updates and video segments upload fine to YouTube - ffmpeg does not report any errors. However the liveStream status always shows noData, and the YouTube Live Control Room doesn’t show the stream as receiving data.

  The DASH output, when written to files play backs fine in this test player. The playlist output doesn’t match exactly the samples, but does have the required tags per the "MPD Contents" section in the documentation.

  Are my ffmpeg arguments incorrect, or does YouTube have additional playlist format requirements that are not documented ?

• on-the-fly transcode and stream with VP9 and MPEG-DASH

  18 juillet 2016, par Calvin W.

  In the VOD system, I want to add a unique watermark to the video with FFmpeg, so I need a on-the-fly transcoding and streaming method.

  In this article, it describe how to create non-muxed and chunked WebM files for live streaming. And I tried replacing input with my MP4 file and it can generate chunks of video/audio files.

  Is there any way to generate a VOD-oriented MPD file, which contains video duration, rather than a live stream one ? Thanks.