Vlc is not able to include the audio in the screencast under Windows about ardesia HOT 21 OPEN

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Rationale
We can try to use different tool or library to solve the bug 

The requirements 

- cross plattform screencast 
- realtime recording of the desktop
- realtime recording audio from mic
- the audio and video are interleaved and synch in a container 
- free software
- royalty free formats
- easy to stream
- easy to share 

Seems that the only one candidate format
can be ogg/theora

Seems that the only one library/tool that we can use for the
screencast are
- vlc
- ffmpeg

The ffmpeg has a native X11 grab support and
a patch to grab the desktop video on windows;
read this discussion on this topic and related links 
http://www.elpauer.org/?p=261.
No info about the audio support and audio/video synch.

Anyway, we must see if the ffmpeg cross platform screencast is feasible.
Please contact the developers staff or pot comment to help in this or other 
direction to achieve the goal.

Seems that choosing vlc the only way  to fix the problem is create a directshow 
video device for the screencast

In the future Theora could be replaced with the webm format 
http://it.wikipedia.org/wiki/WebM. So will be nice to have a cross plattform 
grabber a forwarder and a streamer for this format. HTML5 will support WebM and 
then will become easy embed the video in the web.

GUADEC is first event worldwide streamed in WebM by Flumotion an open streaming 
video server that supports WebM http://www.flumotion.net/

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FFmpeg is able to create webm screencast

Pass 1:
ffmpeg -i output.mkv -an -vcodec libvpx -b 1000k -pass 1 our-final-product.webm

Pass 2:
ffmpeg -i output.mkv -acodec libvorbis -ab 128k -ac 2 -vcodec libvpx -b 1000k 
-threads 2 -pass 2 our-final-product.webm

Is it possible to do it in only one pass

The info about the webm screencast are taken from 
http://verb3k.wordpress.com/2010/01/26/how-to-do-proper-screencasts-on-linux/

The issue is changed in medium bacause we are waiting for a serious refactoring 
of the screencast code; this issue will postponed after the Ardesia 1.0 
milestone

Sorry to butt in here, but re: 
> Seems that choosing vlc the only way  to fix the problem is create a 
directshow video device for the screencast

I have recently created a device you can use: 
https://github.com/rdp/on-screen-capture-recorder-to-video-windows-free

http://betterlogic.com/roger/2010/07/how-to-use-vlc-as-a-free-open-source-altern
ative-to-playon-tv

cheers!
-r

Anyway enjoy.

Thanks a lot; I will try this as soon as possible and then I'll see if and how 
integrate it in the Ardesia code

@rogerpack2005 and to all the hackers

I have tested your work and I think that your code is very interesting, I have 
tried it alone and with ffplay and ffpeg successfully but without audio.
Then I have tried to acquire the stream by your "screen-capture-recorder" with 
vlc. 

The command line used is:
vlc -vvv -I dummy --dummy-quiet dshow:// :dshow-vdev="screen-capture-recorder" 
:dshow-adev --sout  
"#transcode{venc=theora,vcodec=theo,vb=512,scale=0.7,acodec=vorb,ab=128,channels
=2,samplerate=44100,audio-sync}:standard{access=file,mux=ogg,dst=test.ogv}" 

I don't know why but vlc crash after a while when attempt to access to the 
device. The strange think is that from the graphic interface I am able to use 
your device and the other one is that the used command line is the same that I 
use with ardesia a part of the beginning part (that say to acquire from the 
direct show devices). 

I have tested the same command line with the webcam video device erasing the 
screen capture flag (="screen-capture-recorder"); in this way I have 
successfully produced the webcam video with audio; VLC crashs when I open it 
but ffmplay visualize this correctly (but this is an other history, I think). 
I'm using vlc 1.1.11 (32 bit) on a windows 7 home 64 bit.

Coming back to your virtual device; seems that or VLC is bugged or that your 
code is not compliant with VLC.

Please if you are reading this post help me to solve the problem...

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I think I've had some other reports of it crashing when transcoding I'll have 
to look into that.

also note that virtual audio capturer can only be used in vista+ XP users will 
have to manually select "waveout mix" as their selected sound card record from 
device.

I'm using windows 7

ok I was able to reproduce it (required XP for me) but think I have fixed it.  
Give it another shot.  However I noticed that with some resolution (not 
divisible by 8, maybe a few more?) that VLC records things with slanted messed 
up video (ffmpeg did record all right though) [1].  Oh and having a "record" 
button might be nice too.

Cheers!
-r
[1] http://forum.videolan.org/viewtopic.php?f=14&t=94127

This is a workaround in order to make a screencast on windows using free 
software
in a scriptable way

First of all you need:
- a virtual audio capturer
- a screen capture recorder

Now the screen recorder include the audio support also. Download and run the 
setup from 
http://sourceforge.net/projects/screencapturer/files/setup%20Screen%20Capturer%2
0Recorder%20v0.3.1.exe/download

This will create two virtual directshow devices.

With this command you can chack if the twice program are working well
ffplay -f dshow -i 
audio="virtual-audio-capturer":video="screen-capture-recorder"

In this case you can start todo your screencast:
ffmpeg.exe -f dshow -i 
audio="virtual-audio-capturer":video="screen-capture-recorder" test.ogv

In ffmpeg for windows is available an ffmpeg device for screencast grabbing
ffmpeg -r 15 -f vfwcap -i 0 test.ogv

But the audio does not work

An other interesting program to make a screencast is the Petri Tuonenen' 
jcaster available on http://code.google.com/p/jcaster/

Are there someone available to hack the code to make a script usable in Ardesia?
Is it a better choice the rogerdpack driver?