Recognition fails for some pre-recorded shows: pitch shift

We received a few reports that while recognition usually works fine, it fails on certain music programs, recognizing few or none of the songs played in those particular programs.

We ruled out that it’s because these programs play music that ACRCloud (our recognition provider) doesn’t know. And we ruled out user error—it can happen when people make no mistakes in using Spinitron.

The reports began as stations transitioned to broadcasting more pre-recorded programs owing to difficulty safely operating their studios as the pandemic arrived. Iiuc, the pre-recorded programs are typically produced by individual DJs using whatever means they can muster in conditions of social isolation.

I think something technical in the production of certain programs throws ACRCloud’s recognition algorithms out of whack.

Pitch shift is a likely suspect known to mess with fingerprint matching. It is a simple way to stretch or squeeze a pre-recorded program to fit a time slot by speeding up or slowing down the audio in a file.

For example, a station might set up automation to play 60 seconds of IDs and stuff at the top of every hour followed by a 59-minute program. DJs are told to make their programs’ audio files exactly 59 minutes long: a shorter file will leave dead air and a longer file will be truncated.

DJs can tackle this problem in various ways. One solution is to record a program close to 59 minutes long and then adjust its duration to exactly 59 minutes with pitch shift.

If you’re experiencing problems with recognition like this, contact me or Eva.