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• How to mix multiple audios from the end ?

  24 avril 2020, par Vijay Singh Kholiya

  In my project I have a feature of recording the meeting which is in a form of group discussion consisting of multiple attendees. All attendees will be having their own personal system and they will be accessing that web app through their personal account. Their is one meeting controller(only one person) who starts the recording and for every attendee whether he is present in the same room or is remote, their microphone will be opened and recording will be stored in S3 bucket.

  



  Since I need a single audio file which consists of the whole meeting recording, so I am using SOX for this. But the problem is, what if any attendee attends meeting in between the discussion so he's audio recording length will be smaller than everyone else.

  



  Since I am mixing the audio files to get one file, but for this late commer attendee the mixing will be wrong. So how can I mix the audios from the end instead of starting ?

  


• Adaptive part in MPD using MP4box

  28 janvier 2019, par enigmaVada

  I have used ffmpeg to encode audio and video files of my video sample.mp4 for the dash player. The commands are as follows :

  ffmpeg -i sample.mp4 -s 426x240 -c:v libx264 -b:v 640k -g 90 -an sample_video_240.mp4
  
  ffmpeg -i sample.mp4 -s 480x360 -c:v libx264 -b:v 960k -g 90 -an sample_video_360.mp4
  
  ffmpeg -i sample.mp4 -s 640x480 -c:v libx264 -b:v 1280k -g 90 -an sample_video_480.mp4
  
  ffmpeg -i sample.mp4 -s 1280x720 -c:v libx264 -b:v 2560k -g 90 -an sample_video_720.mp4
  
  
  
  ffmpeg -i sample.mp4 -c:a aac -b:a 128k -vn sample_audio.mp4

  I have generated 240p,360p,480p and 720p videos and audio file.

  Then I have used mp4box to generate the mpd file using the following command :

  mp4box -dash 10000 -rap -profile dashavc264:onDemand -mpd-title BBB -out sample.mpd -frag 5000 sample_audio.mp4 sample_video_240.mp4 sample_video_360.mp4 sample_video_480.mp4 sample_video_720.mp4 

  I am using the dash.js player to play the video. The problem is, the adaptive part of DASH isn’t working. The player is just using the 240p video and not switching to a better format even if proper bandwidth is available. I am checking using the network tab of chrome dev tools.

  What am i doing wrong ? Please help.

  Here is the mpd file for reference :

  <?xml version="1.0"?>
  
  
  
  <mpd xmlns="urn:mpeg:dash:schema:mpd:2011" minbuffertime="PT1.500S" type="static" mediapresentationduration="PT0H1M9.869S" maxsegmentduration="PT0H0M9.985S" profiles="urn:mpeg:dash:profile:isoff-on-demand:2011,http://dashif.org/guidelines/dash264">
  
   <programinformation moreinformationurl="http://gpac.io">
  
    
  
   </programinformation>
  
  
  
   <period duration="PT0H1M9.869S">
  
    <adaptationset segmentalignment="true" lang="und" subsegmentalignment="true" subsegmentstartswithsap="1">
  
     <representation mimetype="audio/mp4" codecs="mp4a.40.2" audiosamplingrate="44100" startwithsap="1" bandwidth="130920">
  
      <audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"></audiochannelconfiguration>
  
      <baseurl>sample_audio_dashinit.mp4</baseurl>
  
      <segmentbase indexrangeexact="true" indexrange="902-1017">
  
        <initialization range="0-901"></initialization>
  
      </segmentbase>
  
     </representation>
  
    </adaptationset>
  
    <adaptationset segmentalignment="true" group="1" maxwidth="426" maxheight="240" maxframerate="30" par="426:240" lang="und" subsegmentalignment="true" subsegmentstartswithsap="1">
  
     <representation mimetype="video/mp4" codecs="avc1.640015" width="426" height="240" framerate="30" sar="1:1" startwithsap="1" bandwidth="590708">
  
      <baseurl>sample_video_240_dashinit.mp4</baseurl>
  
      <segmentbase indexrangeexact="true" indexrange="914-1053">
  
        <initialization range="0-913"></initialization>
  
      </segmentbase>
  
     </representation>
  
    </adaptationset>
  
    <adaptationset segmentalignment="true" group="1" maxwidth="640" maxheight="480" maxframerate="30" par="4:3" lang="und" subsegmentalignment="true" subsegmentstartswithsap="1">
  
     <representation mimetype="video/mp4" codecs="avc1.64001E" width="480" height="360" framerate="30" sar="1:1" startwithsap="1" bandwidth="883873">
  
      <baseurl>sample_video_360_dashinit.mp4</baseurl>
  
      <segmentbase indexrangeexact="true" indexrange="914-1053">
  
        <initialization range="0-913"></initialization>
  
      </segmentbase>
  
     </representation>
  
     <representation mimetype="video/mp4" codecs="avc1.64001E" width="640" height="480" framerate="30" sar="1:1" startwithsap="1" bandwidth="1188712">
  
      <baseurl>sample_video_480_dashinit.mp4</baseurl>
  
      <segmentbase indexrangeexact="true" indexrange="913-1052">
  
        <initialization range="0-912"></initialization>
  
      </segmentbase>
  
     </representation>
  
    </adaptationset>
  
    <adaptationset segmentalignment="true" group="1" maxwidth="1280" maxheight="720" maxframerate="30" par="16:9" lang="und" subsegmentalignment="true" subsegmentstartswithsap="1">
  
     <representation mimetype="video/mp4" codecs="avc1.64001F" width="1280" height="720" framerate="30" sar="1:1" startwithsap="1" bandwidth="2365717">
  
      <baseurl>sample_video_720_dashinit.mp4</baseurl>
  
      <segmentbase indexrangeexact="true" indexrange="914-1053">
  
        <initialization range="0-913"></initialization>
  
      </segmentbase>
  
     </representation>
  
    </adaptationset>
  
   </period>
  
  </mpd>

• doc/developer : move a sentence to a more appropriate place

  20 mars 2023, par Anton Khirnov

  doc/developer : move a sentence to a more appropriate place
  It's targeted at our users, not developers, so it makes more sense to
  
  group it with other text targeted at our users.
  

  • [DH] doc/developer.texi