Re: AUConverter crackling
Re: AUConverter crackling
- Subject: Re: AUConverter crackling
- From: William Stewart <email@hidden>
- Date: Tue, 13 Jan 2004 11:44:45 -0800
On 13/01/2004, at 11:33 AM, John Stiles wrote:
How does this compare to k3DMixerParam_PlaybackRate?
This appears in the Panther distribution (and the QT 6.4 or later
release for Jaguar)
This parameter co-operates with a cheap (linear) resampling algorithm
that we added to the 3D Mixer's inputs. Basically they work as follows:
The 3DMixer will accept a mismatch between the sample rate of any of
its inputs and its output sample rate. If there is a mismatch, a cheap
linear resampling will be done to the input data to bring it to the
output sample rate. The quality of course is not that high, but for
games linear resampling is the norm (that is what the sound blaster
uses for instance)...
Now, additionally, we've added a parameter to each input that allows an
input to be played faster (or slower) than its nominal rate - this is
done through using this resampling as well of course, but it is dynamic
in the same way that the AUVarispeed is dynamic, and can be tweaked as
often as you like.
Meant to write a read me about this - so thanks for the question John
Bill
(When was this added, BTW? If a user has installed QuickTime 6.5, can
we rely on it being there in 10.2.x?)
On Jan 12, 2004, at 3:44 PM, William Stewart wrote:
Yes indeed that does sound like the same problem. The AC's resampler
is NOT about dynamic adjustment (that's why to get a different sample
rate you have to make a new audio converter) and also why we have the
varispeed AU.
Bill
On 12/01/2004, at 7:21 AM, Hugues Pisapia wrote:
Well,
I went back into this thread and it seems to be also a problemk I am
experiencing... I'm using the HAL through Java to access the
recording (and playback) facilities. I want to perform resampling on
the fly and get crackling sound, apparently, between each chunk of
audio that go throught the AC.
Is that the same problem, and do I have to use the AudioUnits as
well? If so... What is the AC for?
Hugues
Stefan Werner wrote:
Hi,
To: email@hidden
From: Chris Rogers <email@hidden>
Subject: Re: AUConverter crackling
The AudioConverter is not designed to change sample-rate on the
fly like
this. The AUVarispeed AudioUnit should be perfectly adapted to
this
application by tweaking the "rate" parameter on the fly.
OK, I'll try that. Is it using FFT or is it doing simple
resampling? I need the latter, that's why I tried the AUConverter.
To me, AUVarispeed sounded more like timestretching than
resampling.
I suppose there's no other documentation than the WWDC presentation
Bill mentioned?
Stefan
http://www.hdm-stuttgart.de/~sw19/audiospace/
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