In C hands every ensemble the same 53 fragments and lets each player decide when to move on, so no two performances match. iNCYNC plays up to six at once and puts a rate slider on each, so a 1968 studio session, a Kyoto temple and a Commodore 64 can lock to one pulse.
The library holds 99 recordings, in date order. Riley’s 1968 Columbia album, added to the National Recording Registry in 2022. The Shanghai Film Orchestra on zither, lute and flutes in 1989. Africa Express with kora and balafon in Bamako. JS666 on a Commodore 64’s sound chip. An “In D” for double basses. A bootleg of Bang on a Can in Berkeley this May, for Riley’s 90th-birthday year. Each card shows the sleeve and opens onto liner notes: where and when, the instruments, and whether it strays from the score. Nine wear a “With Terry!” corner, and filters narrow a channel to Riley’s own, bootlegs, length or ensemble size.
Syncing is by ear. The slider runs from 0.5× to 2×, and a readout under it scales the recording’s estimated tempo. It deals in approximations, “120ish bpm”, and the page admits the figures are “human-tapped” and “probably not quite right”. In the screenshot, six recordings made at 104 to 132 bpm are nudged to about 120. There is no play-all button and no beat detection: you start each channel and drag until the pulses stop fighting, which suits a piece built on players drifting in and out of phase.
A correction to our find: the Kiyomizu-dera performance was not 2023 but 21 July 2024, a full-moon night marking the piece’s 60th year, with about 50 musicians. Riley had stopped playing In C in 2009; this was his return, at 89. The page opens with it loaded beside the 1968 album, the same piece 56 years apart.
Play Along opens a separate window with all 53 fragments on a synthesized marimba: arrow keys step through them, a held key loops one, and an optional high-C pulse keeps time. “Stick together” makes you work through them in order, as the score asks. For the undecided, “In C ∞” in the footer is a radio station, Consistant C: “In many forms. For many hours.”
It is free, with no account, and hand-kept by an unnamed maker who asks for corrections by email. Most recordings link out to Bandcamp or Discogs; the page doesn’t say whether it has permission to stream all 99.