[FFmpeg-user] desktop streaming

[Lou]

On Wed, 19 Feb 2014 17:07:58 +0100
YuGiOhJCJ Mailing-List <yugiohjcj-mailinglist at laposte.net> wrote:

> On Wed, 19 Feb 2014 18:15:43 +0700
> nugroho <nugroho.redbuff at gmail.com> wrote:
> 
> > Hi, I have ffmpeg installed in debian linux. I also have a flash 
> > streaming server located at http://a.b.c.d/app/stream.
> > Now, I would like to stream my desktop include the sound to the 
> > streaming server. So what kind of ffmpeg syntax should be? Is it like 
> > this one bellow?
> > 
> > _ffmpeg -video_size 1024x768 -framerate 25 -f x11grab -i :0.0+100,200 -f 
> > flv rtmp://a.b.c.d/app/__stream_
> > 
> > thanks for help!
> 
> Hello,
> 
> You have all the instructions you need here:
> https://trac.ffmpeg.org/wiki/StreamingGuide

Also see:
http://trac.ffmpeg.org/wiki/EncodingForStreamingSites

> In order to stream, I use the following command:
> ffmpeg -y -f alsa -i default -f x11grab -r 10 -s 640x480 -async 1 -i :0.0 -strict -2 -c:a aac -c:v libx264 -pix_fmt yuv420p -preset ultrafast -s 640x480 -threads 0 -ar 44100 -b:a 64k -b:v 64k -bufsize 64k -f flv "rtmp://live-fra.twitch.tv/app/`cat ~/twitch.key`"

* Is "-async 1" required?

* "-c:a libmp3lame" can be used instead of "-c:a aac -strict -2" if you
  prefer its output.

* "-threads 0" is default for libx264, so you can omit that if you like.

* 64k for video is low (for almost all content at 640x480), but you
  mentioned this already.

* You might be able to use a slower -preset depending on your hardware.

* "-framerate" should be used instead of "-r" for x11grab input.

* I believe Twitch recommends a Group of Pictures interval of 2 seconds,
  so in your example that would be an output option of "-g 20".

* -bufsize for gaming is probably 1-2 seconds (I'm guessing here), so in
  your example that would be maxrate * 1-2 = 64k-128k.

* -maxrate can be ~80% of your upload data rate speed - audio bitrate,
  or if you have a fast upload data rate it can be the minimum download
  data rate speed that you want your viewers to have without additional
  buffering.