[lbotos]

Aside: "A DJ using Ableton Live, a huge bundle of MaxMSP emitting a UDP stream of beat information (courtesy of the immensely pro Cade), a UDP ➝ WebSockets server, and DJGif pulling hundreds of GIFs off various Tumblrs to beatmatch <x-gif> on two projectors makes for a hell of a good show."

Does anyone know why he wouldn't have used the midi clock from Ableton (or other DJ software) to a "midi->websocket" server?

[radiowave]

One reason might be that MIDI clock is just a repeating, identical message. It does not contain any position information (like where the next bar starts). To get positional information relating to beats and bars, you need to use MIDI Song Position Pointers, however these use a 14 bit counter which will typically overflow after about 10 minutes. In short, long-running musical clock sync over MIDI is problematic.

For syncing sound recorders, MIDI Time Code (MTC) is usually used, which works fine for up to 24 hours, but doesn't contain information about bars and beats, so unless the system receiving the MTC has a-priori knowledge of what time locations will correspond to bars and beats (which it typically wouldn't have in the context of a live performance), MTC can't be used for this purpose.

[lbotos]

Sweet! Thanks for the detailed run down. As a DJ myself, at my residency we have a random splattering of strange movie clips that we just play and they are never beat matched but mentally something "always" hits a beat when you are watching it. I guess he's going for stuff actually changing in musical time.

[arthurdenture]

The beat information might have been more elaborately derived from the audio, as opposed to just sending the basic tempo.