Picorder

Picorder receives a digital audio stream — S/PDIF, I2S master, I2S slave on one to four stereo data lines, or an eight-channel ADAT lightpipe — and hands it to a USB host as a class-compliant USB Audio Class 1.0 recording device. There are no drivers to install on macOS, Windows or Linux. It simply appears.

Which input is active, on which GPIOs, how many stereo lines it captures and at what USB wire depth is all runtime configuration. A small vendor control interface lets a host tool switch inputs, move pins and change the USB audio format without reflashing, and the settings persist to flash. Changing the format makes the device re-enumerate itself — no replug.

Whatever the source, the audio is captured without any resampling. A rate-matching servo adapts the USB data rate to the input clock by varying the isochronous packet size each frame. And if a source-clocked input is locked at a rate the host did not select, Picorder streams silence and raises a status flag rather than quietly playing your audio back at the wrong pitch.