HOWTO: Proper Screencasting on Linux

[shantiq]

thanx for that so coool FOM
so handy



one more example

ffcast --xwininfo  -v -t 00:00:30 -r 40 -o  ./Desktop/screencast.mkv

start it click once on the window of your choice and you have 30 seconds recorded in mkv to your desktop brilliant tool


could one add sound?

[FakeOutdoorsman]

@FakeOutdoorsman: Problem with ffcast is that it doesn't support audio, does it?. However, the xrectsel tool is particularly useful. It is brilliant. I think I might add it to the guide.

could one add sound?

No, it doesn't deal with audio. It's one of the TODOs, but this script has not been updated since December 2009. Someone with more interest in using this script and a little bash experience could easily add audio support though.

The best part of this script is definitely xrectsel.

I think it is always better for people to be at "ground zero" and learn ffmpeg itself instead of learning a single purpose interface of another interface. It is for their own good

Yes, I agree, but it is good to have options. I've seen some Ubuntu users interested in this script, but they thought it was for Arch Linux only or didn't know how to get it working or installed.

[shantiq]

it is a really cute tool. ffmpeg "raw" is really quite daunting and yes it has to be one of the best tools ever designed but to learn to use it is really quite a task

what i am saying is that one does not preclude the other

ffmpeg is the forest ffcast a nice glade anyway that's my tuppence worth

[verb3k]

Guide update: Added information about the xrectsel tool to the FAQ section.

[verb3k]

thanx that is just what i was looking for ffmpeg really roks



ok changed it a tad so the file ends up on desktop which i prefer

ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 30 -s 1024x768 -i :0.0 -acodec pcm_s16le -vcodec libx264 -vpre lossless_ultrafast -threads 0 ./Desktop/mydesktop.mkv

i have a question tho how can i do this and also add myself being recorded on the cam can it be done?

You can record webcam feed with ffmpeg by using -f video4linux2 -i /dev/video0. You can record infinite number of streams simultaneously. For example, you can record audio from mic, audio from application, video from screen and video from webcam and store them as 4 tracks in a single file, which you can then import to a video editor like openshot and overlay, mix etc... to get the result you wanted. However, note that the likelihood of your streams getting out of sync is quite high, especially if your computer isn't the latest specs or some Alien technology

[verb3k]

Just curious: I have a 1920x1200 native res. monitor and have used FakeOutdoorsman's Tutorial to compile FFmpeg with x264 and all
available options. My refresh rate is 60hz and no matter what I do I get flicker when using the commands on page one. I also get the same
with Recordmydesktop. Even when I do a screen print, it is not quite right if I tilt the cube or do anything. A regular screenprint comes out OK.
I am using the absolute latest nVidia drivers and everything is amazing!

60hz is the max. for my monitor and I cannot figure out why I get the flicker. I even tried using fps=50 instead of 30 and still I get flicker.

Any help would be greatly appreciated!

Even I tried capturing more than 30 fps and couldn't do it. There seems to be a bottleneck somewhere. You can ask the people at #ffmpeg on irc.freenode.net, they might be able to help.

[verb3k]

Guide updated: Expanded the FAQ section to include information on how to get help.

[shantiq]

You can record webcam feed with ffmpeg by using -f video4linux2 -i /dev/video0. You can record infinite number of streams simultaneously. For example, you can record audio from mic, audio from application, video from screen and video from webcam and store them as 4 tracks in a single file, which you can then import to a video editor like openshot and overlay, mix etc... to get the result you wanted. However, note that the likelihood of your streams getting out of sync is quite high, especially if your computer isn't the latest specs or some Alien technology

Verb thanx for that and God i wish i had the alien technology



this is almost alien and gives me a great webcam with voice combo thanx for the info

ffmpeg -f alsa -ac 2 -i pulse  -f video4linux2 -i /dev/video0 -acodec pcm_s16le -vcodec libx264 -vpre lossless_ultrafast -threads 0 -s 320x240   -r 30   ./Desktop/mywebcam.avi

and if you fancy direct recording to other codecs read here

[dannyboy79]

id like to add to this thread about the hours I spent trying over and over, uploading over and over to youtube and spending time on IRC with FFMPEG people so others won't have to spend the time I did.

When i capture to mkv using this command:

ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 29.97 -s 1024x768 -i :0.0 -acodec pcm_s16le -vcodec libx264 -vpre lossless_ultrafast -threads 0 output.mkv

the audio at the end prior to me hitting "q" is cutoff. not sure why but i can repeat the audio being cutoff all the time. Anyone else seeing this? I added the -r 29.97 because apparently youtube doesn't like anything non-standard FPS and the people on ffmpeg irc chat told me to add it.

Also, when I try to encode it for youtube using the command

ffmpeg -i output-new.mkv -acodec libfaac -ab 128k -ac 2 -r 29.97 -vcodec libx264 -vpre slow -crf 22 -threads 0 pm_message_settings.mp4

youtube totally f's up my clip from a 36 second clip to 3 second clip. it appears to make video super fast and audio normal.

So the great people on ffmpeg irc chat told me to add -vsync 1 to my encode line and it now works. final render command is this:

ffmpeg -i output-new.mkv -acodec libfaac -ab 256k -ac 2 -r 29.97 -vsync 1 -vcodec libx264 -vpre slow -crf 22 -threads 0 pm_message_settings.mp4

I am using ffmpeg SVN-r25112 with the following compile options. configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-pthreads --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libx264 --enable-libxvid --enable-x11grab

I do have composite extra enabled on 10.04 Lucid Lynx for zooming in during my screencast. I have the NVIDIA 96.43.17 driver installed.

SO if anyone else can help with the audio being cutoff prior to hitting the q button please let me know. Shouldn't the audio stop with the video when you hit "q"? thanks for any help

[verb3k]

id like to add to this thread about the hours I spent trying over and over, uploading over and over to youtube and spending time on IRC with FFMPEG people so others won't have to spend the time I did.

When i capture to mkv using this command:

ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 29.97 -s 1024x768 -i :0.0 -acodec pcm_s16le -vcodec libx264 -vpre lossless_ultrafast -threads 0 output.mkv

the audio at the end prior to me hitting "q" is cutoff. not sure why but i can repeat the audio being cutoff all the time. Anyone else seeing this?

This happens when you are recording through pulse (bug?). If you're recording through microphone, replacing -i pulse with -i hw:0,0 will solve your problem.

I added the -r 29.97 because apparently youtube doesn't like anything non-standard FPS and the people on ffmpeg irc chat told me to add it.

Youtube works fine for 30 fps. Both lossless and compressed mp4.

Also, when I try to encode it for youtube using the command

ffmpeg -i output-new.mkv -acodec libfaac -ab 128k -ac 2 -r 29.97 -vcodec libx264 -vpre slow -crf 22 -threads 0 pm_message_settings.mp4

youtube totally f's up my clip from a 36 second clip to 3 second clip. it appears to make video super fast and audio normal.

Not reproducible. Clips compressed with AAC and H.264 in .mp4 are handled properly by youtube and stay at full length.