HOWTO: Proper Screencasting on Linux

[artti]

Tutorial is great! But like user arcmorrison, I also have fps 3. Tips to improve this?

[FakeOutdoorsman]

Please show your ffmpeg command and the complete console output.

[dannyboy79]

im using avconv not to screencast but to livestream to twitch. I found a script and am attempting to use it but it appears like the video codec min and max bitrate and buffsize are missing, where or how exactly would I edit this script so that my video bitrate has different bitrate settings from the audio which is how this script is currently limited based on my testing

INRES="1680x1050"                                            # input resolution
OUTRES="1280x720"                                           # Output resolution
FPS="30"                                                    # target 
FPSQUAL="fast"                                               # one of the many FFMPEG preset on (k)ubuntu found in /usr/share/ffmpeg
# If you have low bandwidth, put the qual preset on 'fast' (upload bandwidth)
# If you have medium bandwitch put it on normal to medium # Write your key in a file named .twitch_key in your home directory

STREAM_KEY=$(cat ~/.twitch_key)  
# This is your streamkey generated by jtv/twitch found at: http://www.justin.tv/broadcast/adv_other

avconv \   
-f x11grab -s $INRES  -r "$FPS" -i :0.0 \   
-f alsa -ac 2 -i pulse  \    
-vcodec libx264 -s $OUTRES -preset $QUAL \   
-acodec libmp3lame -ar 44100 -threads 4 -qscale 3 -b 712000  -bufsize 512k \    
-f flv "rtmp://live.justin.tv/app/$STREAM_KEY"

[FakeOutdoorsman]

This howto is specifically for ffmpeg from FFmpeg.

[dannyboy79]

i didn't think they were that different, i understand preset names are different and some options are named or abbreviated differently but I just need to know where I would insert the min, max, and buffer for my video bitrate. Any help would be appreciated. and actually this thread is titled "Howto: Proper Screencasting in Linux" and doesn't state its for ffmpeg only.

[millerthegorilla]

I was having problems recording sound with ffmpeg screencast as I don't use the pulseaudio sound server. I found this page :

http://stefan.boxbox.org/2011/09/26/...cast-in-linux/

There is a little script that starts ffmep for screenrecording and jack_capture for audio.

When finished, there is also some info about transcoding and interweaving the separate video and audio so that you are left with one file.

The only problem that I now have is that my screen is 1440x900 and even with the ffmpeg parameter video_size set (I have also tried -s) the recorded screen is too short, possibly due to 720p set.

[FakeOutdoorsman]

The only problem that I now have is that my screen is 1440x900 and even with the ffmpeg parameter video_size set (I have also tried -s) the recorded screen is too short, possibly due to 720p set.

Please show your actual ffmpeg command and the complete ffmpeg console output.

[thesleash]

this is command I use for decent quality at low bit-rate.

avconv -f x11grab -s `xdpyinfo | grep 'dimensions:'|awk '{print $2}'` -i :0.0 -r 7 -s 680x384 output.mkv

[willard2]

First of all, i'm not an Ubuntu user. I've used Mandrake/Mandriva since 1997 and i'm currently running Mageia

But this guide was really helpful and i wanted to share one problem that i had. I had the issue that the sound was out of sync everytime, and i googled like a maniac. Tried -vsync and -itsoffset. This thread came up several times and i read and tested but could not come up with a solution until i nearly gave up.

I thought to hell with this and deleted the output file. An hour later... Ok, one last try and it worked

Apparently when i pressed enter to start recording, ffmpeg asked me if i wanted to overwrite the already existing output.mkv. Ffmpeg had already started recording at this point. The time it took me to press y to overwrite was the offset time in the audio.

Most people try out a few times then do the final recording. Remeber to delete the old, or save to a new file

Don't know about everyone else but i'm a systems administrator and configure servers and write firewalls for a living, i live in a bash script. I was totally unaware and unfamiliar about this as i've never done it before.

This might not apply for everyone. I just thought i'd share this experience in good Linux Spirit and hope it might be of use to someone else. I'd also like to thank the OP for an excellent tutorial.

Merry Christmas everyone

[alanpotteiger]

Hello! I'm not a very experienced person with this type of thing. I have followed the tutorial and have successfully recorded my screen with audio from my microphone, with one problem. For some reason the audio from my microphone is not synced with the video, Is this a common ocurrence? Any fixes or ideas? Thanks!