There’s a lot of confused (and confusing) information online about making OP-1 samples. They have to be 16-bit mono AIF files with a sample rate of 22050 hz.

ffmpeg is a sort of Swiss Army knife for media conversion. Here’s how you use it to make an OP-1 sample out of any audio file :

ffmpeg -i your-input-file.wav -ss 0 -t 6 -c:a pcm_s16le -ac 1 -ar 22050 your_sample_file.aif

This grabs the first 6 seconds of your input file and turns it into an OP-1 sample. If you want a different timespan, specify the start time in seconds with -ss , and the length with -t (six seconds is the OP-1 maximum). You can use decimals to get more precise ranges (eg. -s 10.725 -t 5.93).

This method creates a mono file by mixing the two stereo tracks into one, which could create phasing problems. You can use other mapping methods with ffmpeg, as described here:

https://trac.ffmpeg.org/wiki/AudioChannelManipulation .

ffmpeg runs on pretty much any platform. See https://ffmpeg.org/