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• How can I synchronize audio and video in real-time transcoding using ffmpeg API ?

  25 mai 2023, par qwer

  I was using ffmpeg api for realtime tanscoding, but somethimes when the system resources (memory) become limited , audio and video is out of syn, as i was tanscoding and pushing rtmp stream so it involves both decoding and and encoding , do i need some sync method to solve the problem, on whatside should i do the synchronizton, during the demux decode time or the encode push stream time,thanks in advance.

  


  i was experencing the problem,and i don't konw how to solve the problem , i was trying to sync the pts in the demux period , read the avpacket and sync the time based on current system time,but no luck.

  


• How to calculate byte/index ranges for mpeg-dash MPD file ?

  7 avril 2016, par TheSHEEEP

  I basically know how an .mpd file would have to be structured to support streaming from separate .mp4 (or webm) files.

  However, I would like to implement the "static" (aka "on-demand") method, thus only having one file per quality that I want to offer in the stream.

  In all samples, this is done by supplying the indexRange & range values within a Representation like this :

  <representation bandwidth="2073921" codecs="avc1.4d401f" height="720" mimetype="video/mp4" width="1280">
  
          <baseurl>car-20120827-88.mp4</baseurl>
  
          <segmentbase indexrange="708-1183">
  
            <initialization range="0-707"></initialization>
  
          </segmentbase>
  
  </representation>

  What I could not find out anywhere is how one would calculate the indexRange/range values here, using only ffmpeg (or ffprobe).
  What exactly would one have to do to get those numbers right for arbitrary (yet supported, of course) video files to create the .mpd file for them ?

  Or am I trying to figure out something in vain here and those values are just arbitrary ?

• adaptives links for mpeg dash on wowza server not working, status error 404 Not Found

  12 août 2015, par jobin

  adaptives links for mpeg dash on wowza server not working with me, the following are the steps that I used to publish video on wowza :

  1. I install and configure Wowza server, and I tested it and it is working fine.

  2. Transcode this video using ffmepg (I bring these command from wowza documentation) :

     set inputFile="C :\video\sintel.mp4"
     set outputFile="C :\video\sintel"

     ffmpeg -y -i %inputFile% -s 320x180 -y -strict experimental -acodec aac -ab 64k -ac 2 -ar 48000 -vcodec libx264 -vprofile baseline -level 30 -g 48 -b 200000 -threads 64 %outputFile%_320p.mp4
     ffmpeg -y -i %inputFile% -s 640x360 -y -strict experimental -acodec aac -ab 128k -ac 2 -ar 48000 -vcodec libx264 -vprofile baseline -level 30 -g 48 -b 520000 -threads 64 %outputFile%_640p.mp4
     ffmpeg -y -i %inputFile% -s 320x180 -y -strict experimental -acodec aac -ab 64k -ac 2 -ar 48000 -vcodec libx264 -vprofile main -g 48 -b 270000 -threads 64 %outputFile%_400p.mp4
     ffmpeg -y -i %inputFile% -s 420x270 -y -strict experimental -acodec aac -ab 64k -ac 2 -ar 48000 -vcodec libx264 -vprofile main -g 48 -b 570000 -threads 64 %outputFile%_700p.mp4
     ffmpeg -y -i %inputFile% -s 720x406 -y -strict experimental -acodec aac -ab 128k -ac 2 -ar 48000 -vcodec libx264 -vprofile main -g 48 -b 1000000 -threads 64 %outputFile%_1100p.mp4
     ffmpeg -y -i %inputFile% -s 1024x576 -y -strict experimental -acodec aac -ab 128k -ac 2 -ar 48000 -vcodec libx264 -vprofile main -g 48 -b 1200000 -threads 64 %outputFile%_1300p.mp4
     ffmpeg -y -i %inputFile% -s 1080x608 -y -strict experimental -acodec aac -ab 128k -ac 2 -ar 48000 -vcodec libx264 -vprofile main -g 48 -b 1400000 -threads 64 %outputFile%_1500p.mp4

  3. I test the files and all of them workig fine then I moved these files to wowza content folder and create the smil file as following :

  

  <?xml version="1.0" encoding="UTF-8"?>
  
  <smil title="sintel">
  
    
  
      <switch>
  
        <video width="320" height="180" src="sintel_320p.mp4" systemlanguage="eng">
  
          
  
          
  
        </video>
  
        <video width="640" height="360" src="sintel_640p.mp4" systemlanguage="eng">
  
          
  
          
  
        </video>
  
        <video width="320" height="180" src="sintel_400p.mp4" systemlanguage="eng">
  
          
  
          
  
        </video>
  
        <video width="420" height="270" src="sintel_700p.mp4" systemlanguage="eng">
  
          
  
          
  
        </video>
  
        <video width="720" height="406" src="sintel_1100p.mp4" systemlanguage="eng">
  
          
  
          
  
        </video>
  
        <video width="1024" height="576" src="sintel_1300p.mp4" systemlanguage="eng">
  
          
  
          
  
        </video>
  
        <video width="1080" height="608" src="sintel_1500p.mp4" systemlanguage="eng">
  
          
  
          
  
        </video>
  
      </switch>
  
    
  
  </smil>

  4. I use the mpd file (http://191.237.26.137:1935/vod/smil:sintel.smil/manifest.mpd) with http://www.jwplayer.com/innovation/roadmap/mpeg-dash/

  Result : the video work for first few seconds the stop