HOWTO: Proper Screencasting on Linux

[dannyboy79]

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

Im not sure if you actually tried to upload your clip to youtube but it's weird. the file does play fine in vlc and totem but it's only after it uploads to youtube that it's all screwed if I don't use the "-vsync 1" option to the encode line. Here's a sample if you don't believe me.

http://www.youtube.com/watch?v=kJ7_5b6kw0c

if i run a ffmpeg -i on the mp4 prior to uploading to youtube, the one without the -vsync 1, you can see this.
Stream #0.0(und): Video: h264, yuv420p, 1024x768 [PAR 1:1 DAR 4:3], 226 kb/s, 2.60 fps, 29.97 tbr, 30k tbn, 59.94 tbc

BUT when I use the -vsync 1 the fps and tbr match.
Stream #0.0(und): Video: h264, yuv420p, 1024x768 [PAR 1:1 DAR 4:3], 559 kb/s, 29.97 fps, 29.97 tbr, 2997 tbn, 59.94 tbc

as i stated someone on the ffmpeg irc chat pointed this out to me. whats more weird is that if you don't use the -vsync 1 and instead of using the mp4 container and you use a mkv container on the end of the file name the fps and tbr DO match. So this may be a bug with mp4 but I am not sure.


Next problem is the audio, I will try that although I remember trying to enter that in gtk-recordmydesktop and it returned that it couldn't configure the sound but that may be gtk-recordmydesktop problem. Thanks for trying to help. I'll post back sound result using hw:0,0 after work.

[verb3k]

I'm not saying I don't believe you. I'm saying that I could not get what you desrcibed in the tests I've conducted. I know ffmpeg is one buggy piece of software; it's not unbelievable that problems like that occur to its users

[techunit]

While many screencasting tools exist on Linux, none of them is able to really pull a high-quality screencast. I’ve tried almost all existing tools such as recordmydesktop, xvidcap, istanbul, wink etc.. and all of them produced poor results. Horrible video/audio quality, bad sync, lots of limitations, and some even simply segfault while doing the recording. The real solution and the ultimate answer to all your screencasting needs on Linux has been there for quite a long time. It is called FFmpeg. I am surprised to see that many people would just overlook this awesome piece of software.

I disagree for one reason. Most people who are going to do screencasts seriously are going to be using a VM thus there needs to be something else doing the recording. I ffmpeg is far to hard to get going and it can't be run in a vm.

[FakeOutdoorsman]

I disagree for one reason. Most people who are going to do screencasts seriously are going to be using a VM thus there needs to be something else doing the recording. I ffmpeg is far to hard to get going and it can't be run in a vm.

Please don't quote the whole post. I just created a screencast of a VM creating a screencast: ffmpegvm.mkv.

[.35Whelen]

My goal is to show a screencast of Ubuntu 10.04LTS with Compiz Fusion, full cube rotation, all the great eyecandy in a high graphic environment.
I have followed the tutorial provided by Verb3K


Code:
ffmpeg -f alsa -ac 2 -ab 128k -i pulse -acodec pcm_s16le -f x11grab -r 30 -s 1280x1024 -i :0.0 -aspect 4:3 -vcodec libx264 -vpre lossless_ultrafast -threads 0 SCREENCAST.mkv
Encode

Code:
ffmpeg -i output.mkv -acodec libfaac -ab 128k -ac 2 -vcodec libx264 -vpre slow -crf 22 -threads 0 our-final-product.mp4


This gives me a choppy and lagging fps rate. The bigger problem is audio is not working. I have PulseAudio and pavucontrol set to Microphone1 and have tried it on Amplifier to no avail. What could I be missing? Any info or lead to track down would be appreciated.

[ron999]

I have followed the tutorial provided by Verb3K


Code:
ffmpeg -f alsa -ac 2 -ab 128k -i pulse -acodec pcm_s16le -f x11grab -r 30 -s 1280x1024 -i :0.0 -aspect 4:3 -vcodec libx264 -vpre lossless_ultrafast -threads 0 SCREENCAST.mkv

That command is not the one used in the tutorial.

[.35Whelen]

It was posted #22 on page 3 and seems viable. I have also used the first example:


Code:
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 output.mkv

from the tutorial and all record and encode combinations that Verb3K was kind enough to provide. My preparation consisted of:


For this tutorial, you’ll need FFmpeg (preferably a recent revision) compiled with "--enable-x11grab" and the following libraries:

* libx264
* libfaac
* libmp3lame
* libxvid
* libtheora
* libvorbis

to no avail.

[mocha]

This gives me a choppy and lagging fps rate. The bigger problem is audio is not working. I have PulseAudio and pavucontrol set to Microphone1 and have tried it on Amplifier to no avail. What could I be missing? Any info or lead to track down would be appreciated.

You probably didn't select the proper audio input source in the Pulseaudio recording section after you started ffmpeg. As for lagging capture, maybe your computer specs are too low? What hardware are you running?

[wgilthorpe]

HELP!

Please excuse the yelling, but I am at wits end. I have been successfully recorded a couple of screencasts with ffmpeg and they come out beautifully. My only problem (and it is driving me crazy) is that I want to record both my microphone input and the system sounds simultaneously. I am trying to show a friend who lives far away my Ubuntu theme. I would like to narrate while doing so. If anyone knows how i might accomplish this I would be most grateful.

[.35Whelen]

wgilthorpe


HELP!

Please excuse the yelling, but I am at wits end. I have been successfully recorded a couple of screencasts with ffmpeg and they come out beautifully. My only problem (and it is driving me crazy) is that I want to record both my microphone input and the system sounds simultaneously. I am trying to show a friend who lives far away my Ubuntu theme. I would like to narrate while doing so. If anyone knows how i might accomplish this I would be most grateful.

Ya, I'm not sure why you hijacked my post?