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• Encoding FFMPEG to MPEG-DASH – or WebM with Keyframe Clusters – for MediaSource API

  26 janvier 2017, par Chris Nolet

  I’m currently sending a video stream to Chrome, to play via the MediaSource API.

  As I understand it, MediaSource only supports MP4 files encoded with MPEG-DASH, or WebM files that have clusters beginning with keyframes (otherwise it raises the error : Media segment did not begin with keyframe).

  Is there any way to encode in MPEG-DASH or keyframed WebM formats with FFMPEG in real-time ?

  Edit :

  I just tried it with ffmpeg ... -f webm -vcodec vp8 -g 1 ... so that every frame is a keyframe. Not the ideal solution. It does work with MediaStream now though. Any way to sync up the segments with the keyframes in WebM so not every frame needs to be a keyframe ?

  ---

  Reference Questions on WebM / MP4 and MediaSource :

  Media Source Api not working for a custom webm file (Chrome Version 23.0.1271.97 m)

  MediaSource API and mp4

• lavf : Add WebM DASH Manifest Muxer

  14 juillet 2014, par Vignesh Venkatasubramanian

  lavf : Add WebM DASH Manifest Muxer
  This patch adds the ability to generate WebM DASH manifest XML using
  
  ffmpeg. A sample command line would be as follows :
  ffmpeg \
  
    -f webm_dash_manifest -i video1.webm \
  
    -f webm_dash_manifest -i video2.webm \
  
    -f webm_dash_manifest -i audio1.webm \
  
    -f webm_dash_manifest -i audio2.webm \
  
    -map 0 -map 1 -map 2 -map 3 \
  
    -c copy \
  
    -f webm_dash_manifest \
  
    -adaptation_sets “id=0,streams=0,1 id=1,streams=2,3” \
  
    manifest.xml
  It works by exporting necessary fields as metadata tags in matroskadec
  
  and use those values to write the appropriate XML fields as per the WebM
  
  DASH Specification [1]. Some ideas are adopted from webm-tools project
  
  [2].
  [1]
  
  https://sites.google.com/a/webmproject.org/wiki/adaptive-streaming/webm-dash-specification
  
  [2]
  
  https://chromium.googlesource.com/webm/webm-tools/+/master/webm_dash_manifest/
  Signed-off-by : Vignesh Venkatasubramanian <vigneshv@google.com>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] Changelog
  • [DH] RELEASE_NOTES
  • [DH] doc/muxers.texi
  • [DH] libavformat/Makefile
  • [DH] libavformat/allformats.c
  • [DH] libavformat/version.h
  • [DH] libavformat/webmdashenc.c

• ffmpeg - Seek to absolute time stamp in MPEG DASH segment [closed]

  30 mai 2024, par iBent

  I need to extract short audio segments at specific time stamps from specific dash segments.

  


  I tried the following :

  


  ffmpeg -ss 00:10:00 -i segment_x.m4s -t 10 out.mp3


  


  -ss seeks relative to the segment's start time however, and not absolutely.
That absolute time data is there however as ffmpeg prints it during the conversation like this :

  


  Duration: 00:10:14.01, start: 595.018667, bitrate: 7 kb/s


  


  How can I make ffmpeg extract the audio from exactly 00:10:00 to 00:10:10 ?