DJ Software Update
I hit a brick wall today when I discovered I couldn't mix mplayer's output across two outputs (one for fronts, one for monitoring).

So instead, I went back to review some old DJ software. Mixxx is starting to look much better. It was not hanging and crashing as much as the last time I tried it, and it's under active development. Apparently they are grabbing the attention of hardware controller vendors, who are releasing open source drivers. The beta version even has a scripting environment that looks fun.

BPMDJ also released a new version recently. I guess I'm not real excited about how the interface is put together, but the tempo analysis is top-notch, and using the "beatgraph" visualization to set cue points is a nice tool I've not seen elsewhere.

So after an email exchange with the author, I was able to decipher the binary format used by its index files, and wrote a php script (meh. it was fast, and I knew it) to parse the beat period, calculate the tempo, and use eyeD3 to insert it into the mp3 file's id3 tags. Mixxx, once it loads the file, will then pick the bpm out of that tag, and synchronize track playback based on that.

The beta version of Mixxx also saves cue points in it's library. I wonder if I could translate that to the id3 Event Timing Codes tag? That way all that data is stored in the file.

I suppose I'm about to find out whether the existing tools are useful enough that I won't be reinventing any wheels after all.

Also interesting in the Linux audio front is a recent review of Linux sound drivers, which speaks very highly of OSSv4. There's a widespread impression that OSSv3 was left behind for ALSA back in the day when the the original developer decided to close the source (a more than adequate reason). But since that time, 4front has re-released OSS version 4 under the GPL, giving it an opportunity for a second look. And it's very, very good-looking indeed, with latencies well below ALSA in most cases, backward-compatibility with all ancient applications that never switched to ALSA (indeed, often the problem is that apps don't support OSS), and non-blocking behavior now the default.

I will need to check this out soon.