Re: Are Quicktime microtones supported?
Re: Are Quicktime microtones supported?
- Subject: Re: Are Quicktime microtones supported?
- From: Bill Stewart <email@hidden>
- Date: Wed, 04 Sep 2002 18:47:07 -0700
on 8/21/02 2:25 PM, Joel May wrote:
>
Chris,
>
>
Is there a way to determine the latency of the internal synth?
There is no builtin latency with the synth AU - but of course, you have to
take into account the latency of your I/O path.
CoreAudio reports information from the device about its latency (safety
offset, hardware latency) which you add to the size of the buffer you're
rendering for.
As you construct this yourself, you have a much greater degree of control
over this characteristic
Bill
>
QTMA has a latency field in one of its data structures. I've found this
>
to be very useful when synchronizing graphics. (Altough this field
>
reports the wrong value in QT5 and QT6. I've figured out that it is
>
always off by about 180 ms.) This field is dynamic -- it varies over
>
time. Presumably, when the cpu is busier, the latency increases and
>
this latency is reflected in this field.
>
>
I need the same thing in CoreAudio.
>
>
Thanks,
>
Joel May
>
>
>
-----Original Message-----
>
From: email@hidden
>
[mailto:email@hidden] On Behalf Of Chris Rogers
>
Sent: Tuesday, August 20, 2002 1:06 PM
>
To: email@hidden
>
Subject: Re: Are Quicktime microtones supported?
>
>
Actually you should use the QuickTime mailing list for this question,
>
but I can help you out here. The QT APIs are deprecated and we highly
>
encourage developers to move over to using AudioUnits, the DLS
>
synth, and the rest of our APIs in CoreMIDI, CoreAudio, and the
>
AudioToolbox framework. These new APIs provide more features
>
not accessible from QTMA, as well as being more efficient, etc....
>
>
Anyway, a bug fix for the latest release of QuickTime 6 (in Jaguar)
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should support the
>
fractional pitches as they were originally meant to work. The scale
>
is logarithmic. Fractional pitches are also supported in the
>
DLS synth AudioUnit, although the fraction in this case is the
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fractional part
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(from 0.0 -> 1.0) when using MusicDeviceStartNote().
>
>
Hope this helps...
>
>
Chris Rogers
>
>
>
>
> Does anyone know what the story is about microtonal intonation under
>
> QuickTime? According to the QuickTime docs, NANotePlay is supposed to
>
accept
>
> fractional pitches, though the meaning of the fraction is poorly
>
documented
>
> (logrithmic, or what?). I'm doing this with OS 10.1.5, and in any
>
event, it
>
> doesn't work: QT clearly understands the format, because it plays the
>
> requested midi pitch even though it's shifted - but it ignores the
>
> fractional part. I've tried doing this with the pitches all shifted up
>
what
>
> should be about a quartertone: e.g., middle C would be 0x3C7F (3C is
>
middle
>
> C; 7F is halfway though the unsigned fractional range of 0 - ff). What
>
I get
>
> is just the same pitch as if I had supplied 0x003C.
>
>
>
> It would be a very fine thing if this were made to work. I figure
>
I must
>
> have the format right, given that the basic pitch is understood. Can
>
someone
>
> from Apple comment on any plans regarding this?
>
>
>
> Thanks, Jeff Evans
>
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