Re: Understanding ComplexPlayThru
Re: Understanding ComplexPlayThru
- Subject: Re: Understanding ComplexPlayThru
- From: Neil Clayton <email@hidden>
- Date: Thu, 7 Sep 2006 23:15:52 +0100
That's what is strange - that's what I can see the intention is -
yet, when I remove it completely, it works. I'm happy to post the
code, if anyone is interested ...
On 7/09/2006, at 10:51 PM, William Stewart wrote:
On 07/09/2006, at 3:52 AM, Neil Clayton wrote:
On a more interesting note, I removed the Varispeed unit from the
graph and modified the code so that the DefaultOutput AU stream
format is set to the ouptut format of the AUHAL (element 1).
Now it all 'just works'. I read somewhere that the DefaultOutput
AU had a AudioConverter inside - so assuming that's right and I'm
not making it up, does this mean that the Varispeed is was
required some time in the past, but is no longer? (e.g: old code?)
No.
The varispeed is required to match the potentially different rates
of different and non-synchronised audio devices.
The sample rates should be getting handled like this:
Input Device SR - AUHAL (for input side) - Input of Varispeed
Output of Varispeed - AUHAL (for output side) - Output Device SR
In other words, the varispeed can and should do the rate conversion
(as well as the rate adjustments) between the device being used for
input and the device being used for output. You do this by making
sure that the sample rate between the input of the varispeed and
the device it is getting its data from is the same, and then that
the output of the varispeed is at the same sample rate that of the
device it is outputting its data too.
Bill
Neil
On 6/09/2006, at 9:33 AM, Neil Clayton wrote:
Hi Everyone.
I am currently looking through ComplexPlayThru in order to
understand it better. One of the tests I've been doing is to
use Soundflower as the input, and built-in-audio as the output.
Assuming both use the sample sample rate (which they do, as
confirmed in AMS) things work fine.
If I change the default output device to use a sample rate of
48000, then things are not quite as rosy. There is about 1s
worth of audio played, which is at a lower pitch (I think the
varispeed conversion ration was about 0.91 or thereabouts), and
then it goes pear shaped.
Pear shaped, for the moment I don't mind. What's confusing me
is that I would have thought he varispeed unit would have
accounted for the differences in sample rate, and therefore the
audio wouldn't be heard at a different pitch. Is this correct?
Regards,
Neil Clayton
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