[clug] Recording screencasts on Linux?

[Ian Munsie]

>> The best that I can find so far is ffmpeg, as detailed here:
>> http://nienhueser.de/blog/?p=469 . RecordMyDesktop looks good but it seems
>> to have had no development since 2008.
>
> Works just fine. Does audio - but I suspect just Desktop sounds (teeraw
> might work).  If I remember correctly you need to set the name of the
> saved file and it's location before starting the recording. Output is ogg.


First, I'd recommend using the gtk-recordmydesktop frontend rather
than recordmydesktop directly (unless you want to script it). It
pretty much is a one click solution and seems to work pretty well
whenever I've used it in the past.

I did notice that I had to open it's advanced settings and change the
device in Sound tab from "DEFAULT" to "default" for it to work, and
obviously the Sound recording checkbox should be enabled on the main
interface, but other than that just optionally select a window to
record (which isn't working for me in i3, but that did used to work
when I used in wmii so that might just be a window manager issue),
then hit record. It minimises to the statusbar - simply right click to
pause/resume, left click to stop.


It looks like the sound recording in recordmydesktop uses ALSA, so
that means (honestly the defaults will probably just work so long as
you select the Sound checkbox in gtk-recordmydesktop and changed the
device to "default" - if this looks like too much text to read just
try it and only read this is the audio didn't work):



1. If you DO NOT have pulseaudio installed it will record from
whatever input stream from your sound card ALSA is set to capture from
- probably a microphone (or occasionally nothing at all, in which case
you may need to tweak things in alsamixer's capture tab). Depending on
your sound card you may or may not be able to record desktop sounds,
though nowadays this is actually pretty rare since it requires the
loop back done in hardware on the sound card.

2. If you DO have pulseaudio (and the appropriate ALSA hooks which
your distro should have taken care of for you) you can use pavucontrol
tool (you may need to install this as it is often packaged separately
from pulseaudio) to select where the audio is being routed from:

a) On the Configuration tab you select what mode your sound device[s]
is in (The defaults are usually fine, though it should generally
include the word "Duplex" i.e. both Input and Output work
simultaneously). If you are using another audio device such as a USB
microphone or Bluetooth headset you should check that it's mode is
sensible for recording (Bluetooth devices cannot record in A2DP, for
example).

b) On the Input Devices tab you select which input to use on each
device for recording. The default may be correct, but you should check
in case it's selected the wrong input (My laptop has a built-in
microphone, a microphone jack on the side and a microphone jack on the
docking station). You should be able to see the volume monitor on this
tab moving up and down as you make noises if you selected the right
one.

c) When the application actually opens the sound device for recording,
it will appear in the Recording tab. Let me say that again - the
stream WILL NOT APPEAR on this tab until you actually start recording
with the application! If pulseaudio recognises the application it will
try to assign whatever recording device was used last time to it
(assuming the device is still present and enabled), so if you do a
test run and set it correctly you shouldn't need to change it when you
start recording for real.
One warning - the options that start with "Monitor of ..." are for
recording the sound being sent to the device - i.e. that is how you
would record desktop sounds. If you are recording from a microphone
you want to make sure that you have not accidentally selected the
monitor entry.

The one thing I don't know how to do in pulseaudio, is how to get it
to mix two streams together (say if you wanted to mix both the
microphone input and an output monitor simultaneously). Anyone else on
list know how to do that?

Cheers,
-Ian

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