[RESOLVED] Problems with screen recording

[AlekseyK]

I'm trying to record my screen in background using following command line which was partially copy-pasted from VLC GUI:

vlc screen:// -I dummy --no-video :screen-fps=10 :screen-caching=300 :sout'#transcode{vcodec=mp1v,vb=2000,fps=10,scale=1,width=640,height=480,acodec=none} :no-sout-rtp-sap :no-sout-standard-sap :ttl=1 :sout-keep :file{dst=~/Work/TD_capture.avi}'

I also tried other vcodecs: mp4v, theo, WMV2, mp1v. Have few problems:

• no file created at all, no recording, however...
• high CPU consumption after start is 100% on all the codecs: I saw people able to record desktops with VLC even in h264 format in real time - this one of course not with my PC (old Sempron with 1,6GHz) but it is able to record in mp4 or at least in MPEG-1/2 formats in real time.
• How to stop vlc correctly after it was recording fo some time?
• What is sout and transcode correct syntax is? I read few topics here: there should be a space?

[AlekseyK]

Found correct command line here: viewtopic.php?f=4&t=46971, so 1st and 4th issues are solved. However quit is not clear: command line help says about "vlc vlc://quit", but that url works only if --one-instance option is specified and vlc is in playing mode then another vlc copy with "vlc://quit" parameter leads to both copies quitting. But if vlc is in recording mode then this option does nothing.

About CPU: works fine on my Windows PC with dual core Athlon 3800+ with both h264, mp4v. But on Sempron 1,6 GHz occupies all the CPU, may be because of non-workable video card driver 2D acceleration? Do not know, how to check this?

[AlekseyK]

Also, how to make mouse cursor visible on screencast?

P.S. --screen-follow-mouse does not work. Need to try --screen-mouse-image=<string>?

[AlekseyK]

Disappointment: http://wiki.videolan.org/Interfaces

Note that if you only use the dummy interface, you won't be able to tell vlc to quit (except watching a video).

What to do?!

[Rémi Denis-Courmont]

vlc://quit works fine and the wiki is full of crap. But since screen:// is a never-ending source, VLC will never hit the quit command.

High CPU usage may be due to the high capture frame rate. Screen capture as such is very inefficient; video adapter memory is optimized for output, not for input. In fact, it's even slower on Windows.
For efficiency, you'd need to use Xvfb instead, which tells the application to write to main memory. However then, you would not "see" the application on your screen at all, so it is mostly useless and consequently VLC does not even support Xvfb.

Mouse cursor is not visible. This is partly a limitation of the X11 protocol and partly a limitation of the X11 screen capture plugin in VLC. Patch is most welcome.

[AlekseyK]

I checked yesterday: vlc://quit works fine if run vlc with -I rc or -I hotkeys, etc and with --one-instance option. Then running second vlc copy with vlc://quit quits both. I run following command:

vlc screen:// --one-instance -I rc --screen-follow-mouse --no-video --screen-fps 5 --sout "#transcode{vcodec=mp4v,vb=400,fps=5,scale=1,width=1280,height=1024,acodec=none}:duplicate{dst=std{access=file,mux=ts,dst="/home/alex/Work/TD_capture.avi"}}"

so frame rate is lowest possible. Works fine and very fast on my Windows machine with Athlon X2 3800+ even with h264 codec, and very slow in linux (Sempron 1,6 GHz). May be problem here in X settings or old ATI videocard driver?

[AlekseyK]

Very strange: started to consume a 70-80% of one of CPU's cores under Windows too. What is wrong???!!!

[AlekseyK]

vlc screen:// --one-instance -I dummy --screen-follow-mouse --no-video :screen-fps=5 :screen-caching=300 --sout "#transcode{vcodec=h264,vb=400,fps=5,scale=1,width=1280,height=1024,acodec=none}:duplicate{dst=std{access=file,mux=avi,dst="/home/user/Work/TD_capture.avi"}}" --run-time=1200 vlc://quit

this is final and correct command line to record 20 minutes of screencast video and quit. CPU consumption on my machine (Athlon X2) less than 30%. Previous was not quit correct. Changes are bold.

[AlekseyK]

Here the mouse pointer included, dummy interface DOS box suppressed.

"c:\Program Files\VideoLAN\VLC\vlc.exe" screen:// --one-instance -I dummy --dummy-quiet --screen-follow-mouse --screen-mouse-image="c:\Program Files\VideoLAN\VLC\mouse_pointer.png" --no-video :screen-fps=5 :screen-caching=300 --sout "#transcode{vcodec=h264,vb=400,fps=5,scale=1,width=1280,height=1024,acodec=none}:duplicate{dst=std{access=file,mux=avi,dst="e:\Documents\TD\TD_capture.avi"}}" --run-time=60 vlc://quit