Friday, 9 April 2010

A new unwitting ally in the fight against random orange

I have discovered a new tool in our toolbox in the fight against random test failures: crashinjectdll.dll on Windows, on Linux (I don't know what it's called on MacOS...). I suspect we're randomly injecting crashes into plugins, in order to test recovery from plugin crashes with out-of-process plugins (correct me if I'm wrong). If a mochitest run times out on Tinderbox, and a crash has been injected, when the mochitest run is killed we'll get call stacks in the output log for all the threads that were running. This can give us some details of the state of Firefox when the timeout occurred, and may give us a clue as to why we've timed out.

Maybe we should make always inject a plugin crash at the start of a mochitest run, so that we always have call stacks when we kill a timed-out mochitest run?

Next time someone comments in your random orange bugs with a log, check to see if it's got call stacks in it!

Friday, 2 April 2010

New Ogg video decoder for Firefox

Today I finally landed the new Ogg video decoder for Firefox/Mozilla. It should appear in Firefox nightlies from 2 April 2010 onwards. Chris Double did the initial implementation for the new Ogg decoder, and I took over in December, implemented seeking, and bashed it into shape.

This replaces our old Ogg decoder which used liboggplay. We'll now be able to implement new features easier, and have greater control over our decode pipeline. We can now control our audio and video decode separately, and this allows us to do things like not decoding video interframes if the video decode is taking too much time and causing the audio decode to fall behind. This prevents audio stutter when decoding large-frame-sized videos. The new backend also has more reliable seeking, and can even load a few weirdly formed Ogg files that the previous backend couldn't handle.

It was a large patch, and it's a testament to our robust set of video and audio unit tests that when I checked it into mozilla-central, there was basically only one small fix required. It has been a long grind getting the new decoder to work robustly, but our unit tests have been an invaluable, if fickle, task-mistress.

The new backend should at least be feature-equivalent to the old backend. If you spot a regression in Ogg video playback in new nightly builds, please file a bug in Core in the "Video/Audio" component!