OP-1 Tools

At present, this is just notes about how to create a sample file that's suitable for dragging onto the OP-1's internal USB drive.

Note that I used Ubuntu for this research.

Creating a working sample

1. sudo apt-get install espeak libav-tools
2. espeak -ven-us+f4 -w congrats.wav "Congratulations. Your OP-1 sample work s"
3. avconv -i congrats.wav congrats.aif
4. Plug in OP-1 to computer, shift-COM, drag congrats.aif to synth/user, eject drive, see working sample.

Converting an existing WAV

1. Download wav from [http://www.orangefreesounds.com/amen-break/] and rename to lowercase.
2. Confirm that the sample is 6 seconds or less in length.
3. avconv -i amen-break.wav -ac 1 amen-break.aif
4. Transfer to OP-1. Confirm it works.

Notes

There is a conversion process on the OP-1 after transfer that adds some metadata to the aif file. Here is what I saw after transferring the amen-break.aif file back to my computer:

{
   "adsr":[
      64,
      10746,
      32767,
      10000,
      4000,
      64,
      4000,
      4000
   ],
   "base_freq":440.0,
   "fx_active":false,
   "fx_params":[
      8000,
      8000,
      8000,
      8000,
      8000,
      8000,
      8000,
      8000
   ],
   "fx_type":"delay",
   "knobs":[
      0,
      0,
      32767,
      32767,
      12000,
      0,
      0,
      8192
   ],
   "lfo_active":false,
   "lfo_params":[
      16000,
      0,
      0,
      16000,
      0,
      0,
      0,
      0
   ],
   "lfo_type":"tremolo",
   "name":"amen-break",
   "octave":0,
   "synth_version":2,
   "type":"sampler"
}

For the congrats.aif file, the two 32767 values in the knobs list were 9335. I suspect that I fiddled with the knobs in between imports. I don't know what the knobs mean yet.

It is surprising that amen-break.aif does appear to be based at 440Hz (the higher A key on the keyboard), just as the JSON metadata suggests, but congrats.aif is based at 220Hz (the lower A on the keyboard). I can't figure out why this is the case.