Re: How to implement quick-playing and slow-playing of sound file?
Re: How to implement quick-playing and slow-playing of sound file?
- Subject: Re: How to implement quick-playing and slow-playing of sound file?
- From: "I. Savant" <email@hidden>
- Date: Mon, 23 Mar 2009 14:09:52 -0400
On Mar 23, 2009, at 1:23 PM, mm w wrote:
Hello, it depends if you have time to learn, using AudioUnits is a
long way to go before beeing statisfy, I don't know your background, I
am only an hobbyist musician and doing hobbyist stuff with CoreAudio,
for instance
you have to learn to use AU Lab or create your testing View-tool, + do
you use AUGraph? , + sure it depends on what kind of sound/music...
CORRECTION
You *do not* have to learn to use AU Lab merely to apply this
effect. It is in fact trivial to add this very effect to a QTMovie by
setting the QTMovieRateChangesPreservePitchAttribute attribute on the
movie. You don't even have to deal directly with the AudioUnit behind
it:
[movie setAttribute:[NSNumber numberWithBool:YES]
forKey:QTMovieRateChangesPreservePitchAttribute];
... done.
Now changing the movie's -rate will not bend the pitch (but will
cause audio artifacts to occur - especially when slowing down - if the
rate is too far positive or negative of 1.0. If this limitation is
"acceptable", you're all set. If not, *then* you'll have to drop down
to CoreAudio and write your own (better) AudioUnit to do the same
processing.
While this isn't quite so easy to find (it takes a few minutes of
searching and cross-referencing terms), you should always start with
the highest level possible (in the case of multimedia, it's QTKit),
and only work deeper (CoreAudio) if necessary. In this particular
scenario, it happens to not be necessary.
To "Mac" (the OP), I hope the above code is helpful, though you
really should do the searching to familiarize yourself with the parts
of the documentation that are relevant to this work. It'll help you in
the future.
META-DISCUSSION
As you included me in your reply, "mm w", I must assume you read my
previous post, which mentioned this solution (while leaving the
research to the OP), so I'm not sure what your post adds, besides
confusion and misinformation. Considering yesterday's GC thread
(especially your vague, unsubstantiated assertions) and a quick search
of others like it in the archives, this appears to be a habit of
yours. Please, out of respect for others' time (not to mention your
own pubic image), take greater care in your responses and take the
time to substantiate your assertions with references. You've not been
careful lately and it's demonstrably caused needless confusion and
noise.
APOLOGIES
Apologies to the list and especially to Scott [our moderator, who
art in heaven], for whom this will undoubtedly create drama. This kind
of "help" damages our community and we shouldn't tolerate it.
--
I.S.
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