[LAU] Introductory seq24 tutorial

Leigh Dyer lsd at wootangent.net
Wed Oct 27 00:07:48 UTC 2010

On Wed, 2010-10-27 at 01:11 +0200, Frank Neumann wrote:
> Hi Leigh,
> > I've just posted a video tutorial for seq24 -- it discusses what seq24
> > is, and what it isn't, and then proceeds to demonstrate the basics of
> > building and playing patterns. If you've tried it in the past and been
> > confused by its somewhat unique interface, hopefully this will get you
> > past that initial confusion. The direct Youtube link is here:
> > 
> > http://www.youtube.com/watch?v=J2WDHS1wYeM
> Wow, that is finally one really nice tutorial video - very well done!
> I like the quality of video and sound, the speed, the "entertaining bits" -
> everything really!

Thanks! I've answered your questions below:

> May I ask a few short questions about creation of this tutorial (I tried
> to write them so that a simple yes/no suffices in most cases ;-):
> - What toolchain did you use? Was it the Xephyr/jack_capture/ffmpeg
>   package that others (AutoStatic?) had mentioned here or in other places?

Yep, I used AutoStatic's Xephyr and ffmpeg setup for capturing the
video. For the audio, I recorded straight in to Ardour -- that let me
record the synths I used in to separate tracks so I could adjust the
voice and music levels after recording.

> - What frame rate did you choose for video - 15fps?

I had ffmpeg set to 30 FPS -- I can't say for sure that it captured at
that rate all the way through, but I was definitely happy with the

> - I assume you first write out to disk mostly uncompressed video at the
>   highest possible quality and then do a re-encoding to your selected target
>   video format offline afterwards?

I used ffmpeg's default MPEG-4 compression, but with a very high maximum
bitrate -- that gave me high quality, a manageable (large, but not too
large) file size, and relatively low CPU usage. Here's the command I

ffmpeg -an -f x11grab -s 1280x720 -r 30 -i :2.0 -vb 10000000 tute1.avi

> - Did you experience any audio/video out-of-sync problems which you had to
>   compensate for by e.g. time-stretching the video?

Nope, the audio I exported from Ardour lined up perfectly with the video
from ffmpeg. To make it easier to line them up in Kdenlive during the
edit, I started the video by hitting the "send test note" button in
XSynth; I was then able to line up the button press in the video track
with the sound of the note being played by XSynth in the audio track.

> - Since your voice comes over pretty clear, I assume you did not do live
>   voice recording, but rather overdubbed it afterwards by "watching and
>   commenting" your own video?

For the intro, I recorded the voice independently, and then lined up the
images and slides, and the little "apt-cache search" video, with that --
I made use of Kdenlive's video speed features here to speed through the
footage of the seq24 package installing.

For the rest of the video (the actual screencast), I did just record the
audio and video together in one take -- I had my mic set up so I could
talk in to it comfortably while working. If you listen closely, I'm sure
there are a few mouse or key click sounds in there as evidence of
that :)

If the screencast sounds rehearsed, that's because it kinda was -- I
actually recorded a very similar tutorial screencast a week earlier.
Once I decided to add the intro, though, I scrapped that video and
re-recorded it.


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