byzanz-record cuts recording short when screen is not repainted

[Mitch Curtis]

I'm trying to record interaction with UI controls using byzanz-record, but am running into an issue where it will cut the beginning/end off of a recording if it detects no screen repaints. It can be reproduced by recording a GIF where the mouse is moved within the recording region continuously for the entire duration, and another where nothing happens for the entire duration. The latter will be a millisecond or two in duration.

I figured out that it wasn't working by printing a message to the console every 100 milliseconds to force screen repaints. Even though this occurred outside of the recording region, it still worked. When I knew that that worked, I forced screen updates via QQuickView, but not everyone can or wants to do that.

I'm not sure if this is the correct place to report bugs against byzanz; the only other place I saw was here:

https://bugs.debian.org/cgi-bin/pkgreport.cgi?pkg=byzanz;dist=unstable

Ubuntu release:
Description: Ubuntu 14.04.1 LTS
Release: 14.04

Package version:
byzanz:
  Installed: 0.3.0+git20140123-1
  Candidate: 0.3.0+git20140123-1
  Version table:
 *** 0.3.0+git20140123-1 0
        500 http://no.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages
        100 /var/lib/dpkg/status

[Markus Koschany (apoleon)]

Hello and thanks for the report. I am the Debian maintainer of Byzanz. It is completely fine to report bugs to launchpad.net if you are an Ubuntu user. However you often get faster responses when you report to Debian's bug tracker or to the upstream developers directly.

Though in this case upstream has been pretty inactive for the past years and Byzanz mostly receives language updates.

I can reproduce this bug when I try to record videos without the -c flag, e.g.

byzanz-record test.flv

Without some interaction it will basically record nothing useful at all. You can avoid this behaviour by using the -c flag.

byzanz-record test.flv -c

This seems to trigger screen repaints. I can't reproduce this issue with gif files, the default file format, here it works even without the -c switch.

So it looks like you can circumvent this issue by using the -c flag without having to rely on external tools for screen repaints.

[Mitch Curtis (mitchcurtis)]

That workaround may be fine for some, but for my use case (documentation involving UI controls), it's not desirable to have the cursor included. Good to know, though.