Re: AudioConverter
Re: AudioConverter
- Subject: Re: AudioConverter
- From: Greg Hamilton <email@hidden>
- Date: Wed, 20 Nov 2002 14:29:36 +1100
Cheers, the header file is very useful. I see there's also some html
format documentation for a Java AudioConverter class which has methods
which correspond to the C functions defined in AudioConverter.h so
there are some good clues as to how I might use this.
What's the usual approach to using the AudioConverter ? Is it quick
enough that I could convert data as it's sampled or should I store the
32 bit data and convert it offline ?
Also, I had the perhaps erroneous impression that I should be able to
use AudioStreams to achieve sample rate and buffer format conversion
for the data sent from and received by my Audio Device ioProc ?
I'm not a big fan of ferreting around in header files trying to figure
out how things work, mainly because I'm not very good at it. I'd love
to see some updated docs and sample code for some of this stuff. It's
probably nowhere near as complicated as it seems at the moment, I just
don't know what I'm doing.
Greg
On Wednesday, November 20, 2002, at 01:38 PM, Bill Stewart wrote:
Documentation - what's that:)
AudioToolbox/AudioConverter.h
(seriously, we are trying to get more docs done - this is next on the
list...)
Bill
On Tuesday, November 19, 2002, at 05:05 PM, Greg Hamilton wrote:
Hi,
I've seen a few mentions of the AudioConverter on this list recently.
As usual I don't know what it is or where it's documented.
help ?
Greg
On Tuesday, November 19, 2002, at 01:56 PM, Bill Stewart wrote:
You should use the AudioConverterFillBuffer if you're doing a sample
rate conversion...
The AudioFilePlay code has some fairly comprehensive examples of
using this in several examples in the CoreAudio SDK - PlayAudioFile
is probably the simplest...
Bill
On Monday, November 18, 2002, at 10:58 AM, Martin Hairer wrote:
Hi,
I think a similar issue has already been raised on this list, but I
couldn't find
it and I'm not sure it was really resolved.
The problem I am running into is that of changing the sampling rate
of a piece
of sound using an AudioConverter. When I use
AudioConverterConvertBuffer
with a comfortable value for ioOutputDataSize, I always get a
kAudioConverterErr_InvalidInputSize error, which probably means
that the
AudioConverter would like to fill up my output buffer completely
but doesn't have
enough data in the input buffer. Why doesn't it simply fill up as
much as possible
and writes the achieved size in the ioOutputDataSize variable?
In other words, is there a simple way to tell an AudioConverter to
convert some buffer
of input data into a (big) output buffer and to tell me how many
bytes were actually
written to the output buffer? I must have overlooked something
obvious, since this sounds
to me like one of the main uses for an AudioConverter...
I've already tried to call
kAudioConverterPropertyCalculateOutputBufferSize prior
to AudioConverterConvertBuffer, but it doesn't work either, since
it seems to always
return some minimal (or maximal) size for the buffer, but not the
precise size...
Thanks for any insight,
Martin
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In the beginning, there was nothing, which exploded" - Terry Pratchett
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