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• ffmpeg CMAF support for mpeg-dash

  13 août 2020, par Hobo Joe

  All,
I am trying remux an mp4 as a segmented mpeg-dash stream. I am using libavcodec and the code is exactly like leandromoreira's example, updated to C++14. By setting

  


  av_dict_set(&opts, "movflags", "frag_keyframe+empty_moov+default_base_moof", 0);


  


  I get segmented mp4 files and an MPD to play them with. My question is how I get libav to store my files in a CMAF container ? Is there some kind of flag for CMAF in libavcodec ?

  


• movenc : Allow writing a DASH sidx atom at the start of files

  21 octobre 2014, par Martin Storsjö

  movenc : Allow writing a DASH sidx atom at the start of files
  This is mapped to the faststart flag (which in this case
  
  perhaps should be called "shift and write index at the
  
  start of the file"), which for fragmented files will
  
  write a sidx index at the start.
  When segmenting DASH into files, there’s usually one sidx
  
  at the start of each segment (although it’s not clear to me
  
  whether that actually is necessary). When storing all of it
  
  in one file, the MPD doesn’t necessarily need to describe
  
  the individual segments, but the offsets of the fragments can be
  
  fetched from one large sidx atom at the start of the file. This
  
  allows creating files for the DASH ISO BMFF on-demand profile.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/movenc.c
  • [DH] libavformat/movenc.h

• FFMPEG DASH - Live Streaming a Sequence of MP3 Clips

  4 décembre 2018, par Daniel

  I am attempting to create a online radio application using FFMPEG - an audio only DASH stream.

  I have a directory of mp3 clips (all of the same bitrate and sample size) which I am encoding to the AAC format and outputting to a mpd.

  This is the current command I am working with to stream a single mp3 file :

  ffmpeg -re -i <input />.mp3 -c:a aac -use_timeline 1 -use_template 1 -window_size 5 -f dash <out>.mpd
  
  </out>

  (Input and output paths have been substituted for < input >.mp3 and < output >.mpd in this snippet)

  I am running a web server and have made the mpd accessible on it. I am testing the stream using VLC player at the moment.

  The problem :
  Well, the command works, but it will only work for one clip at a time. Once the next command is run immediately proceeding the completion of the first, VLC player will halt and I need to refresh the player to continue.

  I’m aiming for an uninterrupted stream wherein the clips play in sequence.
  I imagine the problem is that a new mpd is being created with no reference to the previous one, and what I ought to be doing is appending segments to the existing mpd - but I don’t know how to do that using FFMPEG.

  The question : Is there such a command to append segments to a previously existing mpd file in FFMPEG ? or am I coming at this problem all wrong ? Perhaps I should be using FFMPEG to format the clips into these segments, but then adjusting the mpd file manually.

  Any help or suggestions would be very much appreciated !