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• libavcodec with live input

  21 mars 2015, par Kai R

  Is it possible to have a continuous input ?

  Currently I use

  avformat_open_input ..
  
  while (1) {
  
      av_read_frame(pFormatCtx, &packet);
  
  }

  However once the decode catches up to the live input I have problems, is there a better way to do this ?

  In this case my input is a live recording .ts file

• Tips for encoding a live stream to IIS Media Services (or Azure Live Media Services) with FFMPEG ?

  6 mars 2014, par user3104748

  We're trying to encode assets, either live or static, in a live stream to IIS Media Services using ffmpeg. Can anyone provide pointers for exactly what kinds of parameters we should be using and setting ?

  As part of our test, just to see if we can get things to work, we have a standard plain-old MP4 video static asset that we're trying to stream to the server. It seems to work on the client side, but when we try to view the video on the receiving end, we get nothing.

  Here's an example of the command we're using, where gg.mp4 is the static MP4 video (obviously (hostname) is the name of our host and not the actual word in parenthesis :)...

  ffmpeg -y -re -i gg.mp4 -movflags isml+frag_keyframe -f ismv -threads 0 -c:a libvo_aacenc -ac 2 -b:a 64k -c:v libx264 -preset fast -profile:v baseline -g 48 -keyint_min 48 -map 0:v -b:v:0 477k -s:v:0 368x152 -map 0:v -b:v:1 331k -s:v:1 288x120 -map 0:v -b:v:2 230k -s:v:2 224x92 -map 0:a:0 http://(hostname)/ingest.isml/Streams(video)

• Node.js Webm live stream server : issues with tag

  10 décembre 2013, par breathe0

  I'm using Node.js as stream server to stream realtime Webm videos that is sent by FFMPEG (executed from another application, the stream is done via HTTP) and received by a webapp that uses the tag.

  This is what I'm doing : FFMPEG streams the received frames using the following command :

  ffmpeg -r 30 -f rawvideo  -pix_fmt bgra -s 640x480 
  
  -i \\.\pipe\STREAM_PIPE -r 60 
  
  -f segment  -s 240x160 -codec:v libvpx  -f webm 
  
  http://my.domain.com/video_stream.webm

  (the stream comes from an application that uses the Kinect as source and communicates with FFMPEG through a pipe, sending one frame after another)

  When the webapp connects, it receives immediately this response from the server :

  HTTP/1.1 200 OK
  
  X-Powered-By: Express
  
  content-type: video/webm
  
  cache-control: private
  
  connection: close
  
  Date: Fri, 06 Dec 2013 14:36:31 GMT

  and a Webm header (previously stored on the server, with the same resolution and frame rate of the source stream and tested as working on VLC) is immediately appended. Then the webapp starts to receive the data streamed by FFMPEG. Here is a screenshot of Mkvinfo GUI showing the fields of the header :

  

  However, even if the Network tab of the Chrome console shows that there is an actual stream of data (meaning that what is streamed is not completely garbage, otherwise the connection would be dropped), the player doesn't display anything. We tried to manually prepend our header to the dumped video received by the webapp and VLC plays it just fine, but this is not happening with the tag.

  What can cause this problem ? Are we missing something about the encoding on the FFMPEG side or we stored wrong values on the header (or they're not enough) ?

  PS : I cannot rely on an extern stream server.

  PPS : We tried the following experiments :

  • substituting the video header with the one stored in the server makes the video playable on both vlc and video tag
  • if we dump the video that is already started (without an header) and we prepend the video header stored in the server or even its original header, the video is playable in VLC but not on the tag (we're carefully prepending the header just before the beggining of the cluster).