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• Video transcoding during stream

  31 juillet 2017, par Wajahat

  I am trying to setup a testbed that will be used for experimentation, and I have deployed some VMs over Openstack and the setup looks like this currently :
  
  The far right machine is running Apache2 server and video is hosted in /var/www/html/videos folder. VNF1 and VNF2 machines are acting as intermediate routers with static routes configured to route traffic to Apache server machine.

  The client machine runs VLC player to stream video on-demand from the server over HTTP like this :

  vlc http://10.10.2.7/videos/bunny.mp4

  Now, I want to be able to do dynamic transcoding of video while it is being streamed, but I don’t want to do transcoding at server side (for experiment’s purpose the server is not in our control) neither at client side but somewhere in the middle machines (VNF1 for example) so that it is transparent to client.
  Basically, I want to implement video transcoder as a network function.

  I have found FFmpeg which I think should be able to get this done, ffmpeg-server for example allows streaming over HTTP, but I am not exactly sure how to use it for transcoding video traffic ?

• Generate single MPEG-Dash segment with ffmpeg

  25 août 2021, par woubuc

  I've been trying to implement a Plex-like video player that transcodes an arbitrary video file on-demand, and plays it with MPEG-Dash on a webpage. I was able to implement the client side player with the dash.js reference implementation, so it will dynamically request segments from the server (using SegmentTemplate in the mpd file).

  



  But I'm having some problems generating these chunks in real-time. Ffmpeg lets me set -ss and -t to define the boundaries of the segment I need, but they don't play properly in the player because they're "full" video files rather than Dash segments.

  



  So how do I adjust my ffmpeg command to transcode just the part I need as a Dash segment, without having to generate the segments for the entire video file in advance ?

  



  The input video file can be any format, so it cannot be assumed it's in an mp4/dash-compatible codec. So transcoding (with ffmpeg or similar tool) is required.

  



  My current ffmpeg command looks like this (after lots of trying) :

  



  ffmpeg -ss 10 -t 5 -i video.mkv -f mp4 -c:a aac -c:v h264 -copyts -movflags empty_moov+frag_keyframe temp/segment.mp4


  



  The client-side player should be able to buffer the next X segments, and the user should be able to view the current position on the duration bar and seek to a different position. So treating it as a live stream isn't an option.

  


• Java library for converting MP4 to MPEG-2 TS in memory ?

  30 avril 2014, par Lane

  SO...

  I have a Java FX application that runs an embedded HTTP Live Streaming server for video playback using the Media class (NOT live streaming, video on demand). The video playback consists of multiple files that are actually storing a collection of RTP packets. When my HttpHandler is called to handle the get request for the files (entries in the .m3u8 index file), I plan on...

  • Loading the file into memory
  • Creating a byte array of the RAW H264 packets
  • Convert (wrap ?) the RAW H264 to a MPEG-2 TS (ffmpeg -i video.h264 video.ts)
  • Write the MPEG-2 TS contents to the response body so that it can be played

  ...one of my requirements is that I am not able to create local files, even temp ones. So I cannot create a .h264 file, use ffmpeg to create a .ts file, read the ts file and then write the contents to the response body.

  As far as I can tell, Xuggler does not work with streams and JCodec is slow. I am fairly confident that I can dig into and understand the MPEG-2 TS format and simply convert the RAW H264 into the appropriate format, but this seems like a lot of needless work that should have been done before.

  Anyone know of a simple way to convert RAW H264 to MPEG-2 TS ? Or MP4 to MPEG-2 TS ? I can use MP4Parser to create the MP4 data in memory quickly, I just need a java library that can generate MPEG-2 TS data, thanks !