Re: Few sample rate conversion questions
Re: Few sample rate conversion questions
- Subject: Re: Few sample rate conversion questions
- From: William Stewart <email@hidden>
- Date: Wed, 21 Jan 2009 12:54:43 -0800
On Jan 21, 2009, at 5:08 AM, Mike Kluev wrote:
On Wed, 21 Jan 2009 16:00:38 +0300
"Mike Kluev" <email@hidden> wrote:
On Wed, 21 Jan 2009 15:51:48 +0300
"Mike Kluev" <email@hidden> wrote:
On Sun, 04 Jan 2009 23:53:40 +1100 work <email@hidden> wrote:
On Dec 24, 2008, at 7:30 PM, Mike Kluev wrote:
3) For the purposes of sample rate conversion are AUConverter
and AUVarispeed equally good? (Capable to handle the same set of
input/output rates, same quality, etc)
yes - they use the same underlying resampler
Do they use the same resampler as in AudioConverter?
With AudioConverter I can specify both complexity and quality,
to be precise, with kAudioConverterSampleRateConverterComplexity
and kAudioConverterSampleRateConverterQuality.
while with AUConverter and AUVarispeed only "quality".
... with kAudioUnitProperty_RenderQuality.
Does it correspond to the kAudioConverterSampleRateConverterQuality?
Correcting myself: kAudioUnitProperty_SampleRateConverterComplexity
works with AUConverter but not with AUVarispeed, so the following pair
of questions relates to AUVarispeed only:
What complexity do
they use?
'norm'
Can I control it?
no
I also found that they produce initial zeroes in output frames,
while AudioConverter result doesn't have it.
this is the latency of the audio unit - you can throw these out (it
will be the number of samples that correspond to the reported latency
of the AU and that is true for ANY audio unit)
I attribute it to the values of primeMethod & primeInfo that are
controllable with AudioConverter, (however I haven't figured out
yet how to actually control these values correctly with
AudioConverter).
Anyway, is there a way to control prime information with
AUConverter/AUVarispeed?
No - but what you do is a "latency pull" - you pull at least as much
latency samples through the AU providing correct input and then throw
out latency num samples of the output of the AU, then you are good to
go.
Though it is a bit convoluted, you can have a look at auprocess in the
examples, it does all of this for you
Bill
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