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• dash.js not playing mpd file generated by MP4Box

  9 mars 2016, par user3291299

  I have transcoded and stripped the audio of an mp4 file as follows :

  $ ffmpeg -codec:a libvo_aacenc -ar 44100 -ac 1 -codec:v libx264 -profile:v baseline -level 13 -b:v 2000k dir/out.mp4 -i dir/original.mp4

  $ ffmpeg -i dir/out.mp4 -an dir/out_an.mp4

  I’ve used the following MP4Box command to generate a mpd :

  $ MP4Box -dash 30000 -dash-profile on-demand -segment-name out-seg -out dir/out_dash dir/out.mp4

  This results in the following mpd file :

  <?xml version="1.0"?>
  
  
  
  <mpd xmlns="urn:mpeg:dash:schema:mpd:2011" minbuffertime="PT1.500000S" type="static" mediapresentationduration="PT0H2M11.77S" profiles="urn:mpeg:dash:profile:full:2011">
  
   <programinformation moreinformationurl="http://gpac.sourceforge.net">
  
    
  
   </programinformation>
  
  
  
   <period duration="PT0H2M11.77S">
  
    <adaptationset segmentalignment="true" maxwidth="640" maxheight="360" maxframerate="30000/1001" par="16:9">
  
     <contentcomponent contenttype="video" lang="und"></contentcomponent>
  
     <contentcomponent contenttype="audio" lang="und"></contentcomponent>
  
     <representation mimetype="video/mp4" codecs="avc1.42c00d,mp4a.40.02" width="640" height="360" framerate="30000/1001" sar="1:1" audiosamplingrate="44100" startwithsap="0" bandwidth="2097272">
  
      <audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"></audiochannelconfiguration>
  
      <segmentlist timescale="1000" duration="30046">
  
       <initialization sourceurl="out-seginit.mp4"></initialization>
  
       <segmenturl media="out-seg1.m4s"></segmenturl>
  
       <segmenturl media="out-seg2.m4s"></segmenturl>
  
       <segmenturl media="out-seg3.m4s"></segmenturl>
  
       <segmenturl media="out-seg4.m4s"></segmenturl>
  
       <segmenturl media="out-seg5.m4s"></segmenturl>
  
      </segmentlist>
  
     </representation>
  
    </adaptationset>
  
   </period>
  
  </mpd>

• How to set segment duration of a DASH stream using ffmpeg ?

  25 juillet 2024, par ipartola

  I am trying to convert a video to a live DASH stream using ffmpeg. The command looks like this :

  


  ffmpeg -i input.mp4 -preset veryfast \
-c:v libx264 -pix_fmt yuv420p -map 0:v:0 \
-s:0 1280x720 -b:v:0 2M -maxrate:0 2.5M -bufsize:0 4M \
-use_template 1 -use_timeline 1 -seg_duration 1 -f dash foo/stream.mpd


  


  I would like to have the segment duration be 1 second long. However the above command seems to produce chunk files about 8 seconds long instead. However if I change the command to the following (adding -g 5) :

  


  ffmpeg -i input.mp4 -preset veryfast \
-c:v libx264 -pix_fmt yuv420p -map 0:v:0 \
-s:0 1280x720 -b:v:0 2M -maxrate:0 2.5M -bufsize:0 4M \
-g 5 \
-use_template 1 -use_timeline 1 -seg_duration 1 -f dash foo/stream.mpd


  


  I get chunk files that are much closer to 1 second long. Obviously this isn't ideal since that will produce a keyframe every 5 frames. So :

  


  a) I don't understand the relationship between seg_duration and keyframe interval. Why is ffmpeg not automatically just putting a keyframe at the beginning of each chunk ?

  


  b) How do I get the chunk/segment length I want ?

  


• FFplay only plays MPEG-DASH when in the same directory

  26 mars 2020, par M. Parker

  I’ve created a series of video segments using dashenc.c from ffmpeg’s libav on my windows machine. The mpd file is templated, so it’s fairly simple and it passes validation. The video plays, but only if I put ffplay in the same folder as all the files and use :

  ffplay -i manifest.mpd

  If I try to play from some other directory, or even the same directory using :

  ffplay -i c:\tmp\manifest.mpd

  or

  ffplay -i c:/tmp/manifest.mpd

  The attempt fails, producing this error :

  [dash @ 0000016ce0d69900] Failed to open an initialization section in playlist 0
  
  [dash @ 0000016ce0d69900] Error when loading first fragment, playlist 0
  
  C:/tmp/manifest.mpd: Invalid argument

  The mpd file :

  <?xml version="1.0" encoding="utf-8"?>
  
  <mpd xmlns="urn:mpeg:dash:schema:mpd:2011" profiles="urn:mpeg:dash:profile:isoff-live:2011" type="dynamic" minimumupdateperiod="PT500S" suggestedpresentationdelay="PT4S" availabilitystarttime="2020-03-23T14:54:16Z" publishtime="2020-03-23T14:54:25Z" timeshiftbufferdepth="PT4811H53M52.3S" minbuffertime="PT9.6S">
  
      <programinformation>
  
      </programinformation>
  
      <period start="PT0.0S">
  
          <adaptationset contenttype="video" segmentalignment="true" bitstreamswitching="true">
  
              <representation mimetype="video/mp4" codecs="avc1.42001e" bandwidth="5953124" width="720" height="480">
  
                  <segmenttemplate timescale="1000000" duration="5000000" availabilitytimeoffset="4.967" initialization="init-stream$RepresentationID$.m4s" media="media-stream$RepresentationID$-$Number%06d$.m4s" startnumber="1">
  
                  </segmenttemplate>
  
              </representation>
  
          </adaptationset>
  
      </period>
  
  </mpd>

  Adding in a BaseUrl element didn’t help ; my guess is I’m formatting it wrong. Any ideas what I might do to fix this ?