TapeDeck 1.0.1

I'm pretty stoked about releasing TapeDeck 1.0.1 today. It contains some huge audio code overhaulin' that I started about a week before we shipped 1.0…

Just before we shipped TapeDeck, I noticed there was some utterly horrible skipping during audio playback. I attributed the skipping to a small jump in our CPU usage, right after adding the new Core Animation-powered HUD. It was so bad that TapeDeck was nearly unusable. This caused me to spend a 12h day rewriting our audio playback code (in a branch!).

The new code followed Apple's recommendation for high-performance glitch-free audio playback. So I created a separate high-priority feeder thread reading chunks of a file's audio data into a ring buffer that was consumed on the high-priority AU render thread.

I was about 80% done this rewrite when I realized that it was a different bug that caused this unbearable skipping to occur. I don't recall the specifics, but I think I was re-seeking the file accidentally when some unintentional extra KVO updates got triggered. It was caused by the new HUD changes I checked in—are you surprised? :P

Content with the performance of the audio engine on my test systems (an 8-core Mac Pro, and a PowerBook G4 1.5), we shipped TapeDeck. Unfortunately, it still wasn't perfect. I got reports that recent MacBook Pro machines were also experiencing the skipping, and some more heavy-duty testing on my PowerBook G4 was causing the skips to show up more often.

Well it was a good thing I kept the rewritten audio engine in a branch! I merged that branch with what we released in 1.0, and completed the last 20% of the rewrite. TapeDeck 1.0.1 contains this new, more efficient playback engine which should take up slightly less CPU time, and skip a lot less frequently (never say never!).

Unfortunately, I can't say that the skips in playback are completely gone on my PowerBook G4 when you heavily load the system (I was able to get a few skips while doing compiles in Xcode), but they're greatly reduced. On the other hand, I am unable to get TapeDeck 1.0.1 to skip on my wife's MacBook Pro, even when pushing it pretty hard by browsing our very large collection of RAW photos in iPhoto—an operation that brought TapeDeck 1.0 to tears.

Anyway, this was the fix that required the largest effort in TapeDeck 1.0.1. I hope it solves the skipping problem completely for our users!