Re: fractional pitch on ios
Re: fractional pitch on ios
- Subject: Re: fractional pitch on ios
- From: Jeff Evans <email@hidden>
- Date: Sun, 07 Jul 2013 12:01:01 -0700
Ian,
I'm an old reader, though not necessarily alert.
You seem to be telling me that that CoreAudio on ISO supports the MIDI Tuning Standard. Have you tested that? Really, I've never found a device, software or hardware, that did. The software I'm working on must use just the built-in sound; no external hardware at all.
And the way that StartNote does it is so elegant and simple, too. MTS specifies in Hertz, and of course the Hertz difference for a given cents deviation varies by pitch. StartNote specifies in fractions that correspond to cents (e.g. .5 means 50 cents), so that it's not necessary to calculate Hertz for every modification of pitch. Cents are what count!
All I need is accuracy down to one cent. The 1/100 cent specified in MTS is way below the limits of human perception anyway, and this is not for scientific but for musical purposes. MTS seems bulky in any event and I have a hard time believing that it won't introduce serious lagging in polyphony, even if it works. But I'm interested in knowing if it does actually work with CoreAudio. My faith is not strong.
Jeff
On Jul 7, 2013, at 10:17 AM, Ian Kemmish wrote:
On Sun, 07 Jul 2013 at 08:48:59 -0700 Jeff Evans <email@hidden> wrote:
> Pitch Bend is not precise enough for the purpose, and I think it also affects all notes at once. But the Mac is unique in allowing individual notes to be adjusted by fractions - really a wonderful feature.
The way I understand it, it originally appeared in the Quicktime API, and then CoreAudio sort of inherited it. There was a time in the mid-2000's when every time I suggested someone exploit it, someone from Apple popped up and warned that the StartNote API might disappear at any moment :-)
> The MIDI Standard includes a similar capability but I've never found a device that supports it, and it's hardly documented.
I found http://www.midi.org/techspecs/midituning.php to be perfectly adequate for implementing it. They do note that this is an "updated" version of the original documentation, though:-).
If you're trying to decide which trick to implement, I'd recommend MIDI tuning, as it supports a far finer pitch resolution (unless my memory is going, the Quicktime spec only *promises* to honour seven fractional bits, although the Core Audio documentation doesn't say anything about that, and if you're in a situation where Core Audio is just passing the parameters straight through to your Audio Unit, then you normally get away with it!), and it lets you talk and listen to non-Apple stuff (I use it to let my Android Bosanquet keyboard control my Mac OS based synth).
Alert and old readers of this mailing list may remember that I didn't always recommend MIDI Tuning. Hey, I'm allowed to change my mind, right?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Ian Kemmish 18 Durham Close, Biggleswade, Beds SG18 8HZ
email@hidden Tel: +44 1767 601361 Mob: +44 7952 854387
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
--
If this email is spam, report it to
https://support.onlymyemail.com/view/report_spam/MTAxOTYyOjE1NTg1Njk5MDA6amV2YW5zQGFycy1ub3ZhLmNvbTpkZWxpdmVyZWQ
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden