6 ms·

MIDI provides polyphonic aftertouch as a standard (i.e. not NRPN or SysEx) message type. I've read the standard and this sounds very wrong to me. If it is in t

by smosher 14y ago

MIDI provides polyphonic aftertouch as a standard (i.e. not NRPN or SysEx) message type. I've read the standard and this sounds very wrong to me. If it is in the spec then I know a few synths that are broken.

colanderman 14y ago
Most synths don't produce that message (status 0xAx where x is the channel), but rather the more generic Channel Aftertouch message (0xDx). (Edit: whoops, I'm bad at converting bin->hex.)
- smosher 14y ago
  I was going to ask about the message details but I figured it would make me sound like an asshole, so thanks for that. I've looked for this kind of message specifically and not found it in the spec. Does it specify a note number or do something odd? FYI, I wasn't worried about synths generating the message but rather receiving it. It's not too hard to tell whether a synth has a concept of per-note aftertouch, but I guess if it's two distinct messages it's okay to be selective about which you support.
  - colanderman 14y ago
    Yes, the message format of polyphonic aftertouch is similar to that of a note on event (= note # + pressure). Channel aftertouch includes only the pressure. In case you're interested, I e-mailed to the address on your GitHub a copy of the message formats from the MIDI spec. I don't know where I found it (it's not freely available) or else I'd have linked it.
    - smosher 14y ago
      Thanks, that may come in handy.
    - unwind 14y ago
      This page: http://www.srm.com/qtma/davidsmidispec.html http://www.srm.com/qtma/davidsmidispec.html (which is quite obviously highly unofficial) mentions both 0xAx and 0xDx, calling them "Key Pressure" and "Channel Pressure", respectively. The explanation says: Some keyboards can detect a change in pressure on each key, while they are held by the player; these keyboards can report "key pressure" over MIDI. Some keyboards may sense the overall pressure on the device, such as with a weight sensor beneath the entire keyboard. These devices can report "channel pressure." Sounds pretty nice.

by smosher 14y ago

colanderman 14y ago

Most synths don't produce that message (status 0xAx where x is the channel), but rather the more generic Channel Aftertouch message (0xDx). (Edit: whoops, I'm bad at converting bin->hex.)

smosher 14y ago
I was going to ask about the message details but I figured it would make me sound like an asshole, so thanks for that. I've looked for this kind of message specifically and not found it in the spec. Does it specify a note number or do something odd? FYI, I wasn't worried about synths generating the message but rather receiving it. It's not too hard to tell whether a synth has a concept of per-note aftertouch, but I guess if it's two distinct messages it's okay to be selective about which you support.
- colanderman 14y ago
  Yes, the message format of polyphonic aftertouch is similar to that of a note on event (= note # + pressure). Channel aftertouch includes only the pressure. In case you're interested, I e-mailed to the address on your GitHub a copy of the message formats from the MIDI spec. I don't know where I found it (it's not freely available) or else I'd have linked it.
  - smosher 14y ago
    Thanks, that may come in handy.
  - unwind 14y ago
    This page: http://www.srm.com/qtma/davidsmidispec.html http://www.srm.com/qtma/davidsmidispec.html (which is quite obviously highly unofficial) mentions both 0xAx and 0xDx, calling them "Key Pressure" and "Channel Pressure", respectively. The explanation says: Some keyboards can detect a change in pressure on each key, while they are held by the player; these keyboards can report "key pressure" over MIDI. Some keyboards may sense the overall pressure on the device, such as with a weight sensor beneath the entire keyboard. These devices can report "channel pressure." Sounds pretty nice.