Obtaining and running Unity 8 Desktop Preview
If you like playing with new toys you might have already downloaded and tried the Unity 8 Desktop Preview (available here: http://cdimage.ubuntu.com/ubuntu-desktop-next/daily-live/current/)
If you haven’t, you should take it for a spin. If you have an Intel graphics everything should be fine and dandy, if not YMMV at the moment.
- Download the ISO
- Find a spare >1GB USB thumb drive
- Run “disks” via the dash
- Highlight your USB drive and from the cog icon on the right choose “Restore Disk Image…”
- Select your ISO and “Start Restoring” – this will of course erase everything else on your USB stick
You can now boot from your USB stick and have a play with Unity 8. Right now you’ll be seeing the Phone view of Unity 8, but that will all be changing in time.
Capturing a screencast
Once you’ve got everything up and running you might like to make a few screencasts, so how do you do it? Well, the Mir developers have provided us with the mirscreencast tool so let’s use that:
Switch to tty1 (ctrl+alt+f1) and log in and run:
mirscreencast --file <output file> -m /run/lightdm-mir-0
Then switch back to tty8 (ctrl-alt-f8) and use Unity.
Your file will now be filling up FAST. Mirscreencast will be trying to write every raw frame to that file, probably at a rate of 60 frames a second. To kill mirscreencast I first hit ctrl-z and then:
pkill -9 mirscreencast
but there is probably a better way.
Capturing a better screencast
There are a few command line options for mirscreencast which will can help us shrink the file size a bit:
mirscreencast --file <output file> -m /run/lightdm-mir-0 -s 683 384 -n 3600
The option “-s” will resize the captured frames. Note that 683 384 is exactly half my native resolution, so you will need to adjust this to your display.
The option “-n” will capture n frames and then stop. At 60 frames a second, 3600 frames is one minute. If you use -n then mirscreencast will exit gracefully at the end.
Playing back your screencast
I am lucky enough to have a spare machine with a touch screen just for running Unity 8 on (http://www.dell.com/uk/dfh/p/inspiron-11-3137/pd) so I SCP the raw video file on to my main machine for playback and editing.
I use mplayer for most of my video playback and encoding needs and it will happily play the raw video file, but it needs a few pointers:
mplayer -demuxer rawvideo -rawvideo fps=60:w=683:h=384:format=bgra <filename>
or, to convert the raw file into something which you can edit in OpenShot try this:
mencoder -demuxer rawvideo -rawvideo fps=60:w=683:h=384:format=bgra -ovc x264 -o <output filename> <filename>
And then you can edit and upload the processed file. When I export from OpenShot I use the “Web” profile, then target “YouTube-HD”, “HD 720p 29.97 fps” “Med” – it’s a bit overly compressed, but it looks OK.