Re: QT7 changes behavior of AudioConverterConvertBuffer
Re: QT7 changes behavior of AudioConverterConvertBuffer
- Subject: Re: QT7 changes behavior of AudioConverterConvertBuffer
- From: William Stewart <email@hidden>
- Date: Mon, 2 May 2005 14:31:33 -0700
On 01/05/2005, at 8:42 PM, Tim Dorcey wrote:
In case anyone else is having problems with audio corruption after
QT7/Tiger
installation, you might have a look at places you are using
AudioConverter.
I had been trying to use AudioConverterConvertBuffer for sample rate
conversions, which seemed to work fine before QT7/Tiger.
We've been telling people since at least Jaguar, that ConvertBuffer
should *not* be used to do sample rate conversions. We don't test
this code path either. AudioConverterFillComplexBuffer is the way to go.
On one system that I got some debugging going on, ConvertBuffer was
returning an error code of 1768846202
Input Size Error (insz)
on alternating calls, causing me to
ignore that chunk of audio.
If I just ignore the error code instead, it
apparently sounds okay, though I haven't confirmed it is exactly
right.
Also, I was surprised to see it always returning the same amount of
data for
a given amount of input data, when I would expect it to be
periodically
outputting accumulation of "fractional" samples (as it does on my
pre-QT7
system).
It may also be that ConvertBuffer has not changed, but
AudioConverterGetProperty is behaving differently for
kAudioConverterPropertyCalculateOutputBufferSize. I was using that to
determine how much data to ask ConvertBuffer to produce. Perhaps
GetProperty is ignoring internally accumulated state, and then maybe
1768846202 means I didn't allow enough output for all the input.
Not sure if this is a bug, since I can't seem to find any
explanation of how
things are supposed to work. Perhaps I just got lucky prior to QT7.
Yes (as I said, we don't test this code path) - you should be using
AudioConverterFillComplexBuffer
Does anyone know where is the hidden trove of CoreAudio docs?
Bill
Tim
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden
--
mailto:email@hidden
tel: +1 408 974 4056
________________________________________________________________________
__
"Much human ingenuity has gone into finding the ultimate Before.
The current state of knowledge can be summarized thus:
In the beginning, there was nothing, which exploded" - Terry Pratchett
________________________________________________________________________
__
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden