[FFmpeg-user] How to grab the desktop in the webm format

[Alexandre Almeida]

Hi!

Nice to meet you.
First of all, let me introduce myself to this group: my name is
Alexandre. I am a 44 y. o. man who work in the central library of the
"Health Sciences Center" of the UFRJ (Federal University of Rio de
Janeiro). At home, I only use Linux to all the tasks. Sometimes, I
like to record the desktop, as you can see in the link below:

http://lugarparaler.com/conheca-o-retext.html

I always use "Simple Screen Record" to do this, but in the last days
I've heard, for the very first time, about the webm format (and the
webp for pics). And then I've googled trying to find a way to grab my
desktop and save it directly in this format.

I've found out the FFMPEG website and read the documentation. I've
made some tests in the terminal, and I was very happy to discover I
can grab my desktop with very good sound and video using the following
command line:

# ffmpeg -video_size 1600x900 -framerate 30 -f x11grab -i :0.0 -f alsa
-ac 2 -i hw:0 -c:v libx264 -qp 0 -preset ultrafast capture.mkv

The above command is a mix of several "copy and paste" from pieces of
text from the FFMEPG website, and I am not sure if I really understand
what all the options do, to be honest... let's say I was lucky...

But I really can't understand how to save the video in the webm
format. If I change the "capture.mkv" for "capture.webm", I get an
error message in the terminal.

Could anybody please send me a command line to grab my desktop and
save it in the webm format?

I'm sorry if I'm making an obvious question... and sorry for my english too...

Thanks in advance.

Alexandre.