[LAU] JACK screencasting guide

I've just wrote a HOWTO for the AV Linux forums on how I created my A3 MIDI vid which is basically a refinement of Jeremy's JACK screencast tutorial with a couple of extra tips bolted on: http://www.remastersys.com/forums/index.php?topic=1362.0 JACK Audio Screencasting (aka The making of 'Introduction to Ardour 3.0 MIDI') This tutorial is largely based upon an earlier one by AutoStatic here: http://apps.linuxaudio.org/wiki/screencasttutorial Unfortunately, that didn't quite work for me so here I present what I had to do to get a nice JACK-friendly screencast captured. You will need a couple of packages not included by default in AV Linux 4.2, namely the ssh server and the Xephyr nested X server apt-get install openssh-server xserver-xephyr fluxbox Fluxbox is entirely optional, its just what I'm using in this example. Before running Xephyr, our 'nested X server' which will be our desktop to capture, you need to start the ssh server, so do so as root: /etc/init.d/ssh start Then I run the following commands to to start Xephyr then launch fluxbox within it - just replace 'iatn' with your username: Xephyr -ac -host-cursor -screen 1280x720x24 -dpi 96 -br -reset-terminate 2> /dev/null :1 & DISPLAY=:1.0 ssh -XfC -c blowfish iatn@localhost fluxbox Note that after typing 'DISPLAY=:1.0' you need to issue a 'DISPLAY=:0.0' to launch programs on your regular desktop again. Now you can run a script like: ------------- #!/bin/bash DATE=`date +%Y%m%d` TIME=`date +%Hh%M%S` export DISPLAY=:1.0 # Start screencast xterm -display :0.0 -e jack_capture --port system:capture_1 --port system:playback_1 ~/a3midvid/a3midvid_audio_$DATE-$TIME.wav & ffmpeg -an -f x11grab -r 30 -s 1280x720 -i :1 -vcodec libx264 -vpre lossless_ultrafast -threads 2 ~/a3midvid/a3midvid_video_$DATE-$TIME.mkv -------------- That should capture the video on your Xephyr desktop as well as creating a stereo wav with one channel consisting of a JACK output channel and the other one capturing the mic connected to your first mic input. To fix the keyboard problem (like arrow keys not working) under Xephyr, start Xephyr/fluxbox/xterm, input something via the keyboard to Xephyr and then in a terminal on the host X server (not in Xephyr) do: DISPLAY=:0.0 xkbcomp $DISPLAY :1 This copies the XKB settings from the encompassing X server to the Xserver under Xephyr. When I imported my video and audio streams into KDEnlive I found I had to displace the audio stream about 9 frames behind the video but this value could well vary depending on numerous factors so some experimentation may be required to get the audio and video to sync properly.