Default Audio Output Stream Format - 32 bit float only?
Default Audio Output Stream Format - 32 bit float only?
- Subject: Default Audio Output Stream Format - 32 bit float only?
- From: "Tracy Lakin" <email@hidden>
- Date: Thu, 6 Jun 2002 14:40:36 -0700
- Thread-topic: Don't touch this - was QT6 & AAC Encoding
Hi,
The Default Output Unit seems to be buggy about supported stream formats.
The Default Output Unit has a default stream format of 32 bit float / 44100Hz. If I set it (SetProperty kAudioUnitPpoperty_StreamFormat) to 16 bit int / 44100Hz, it does not complain. No error. But if I immediately then get the stream format, it is still at the original 32 bit float format.
Also, if I create a connection between the Default Output Unit and another audio unit, where the other unit has a default stream format of 16 bit int / 44100Hz, the output unit does not complain or return any error. I can verify that the stream format of the audio unit is fetched by the output unit. Yet fetching the Default Output Unit's stream format after the sucessful connection still gives back the original 32 bit float / 44100Hz format.
Assuming that the Default Output Unit and the Audio Unit SDK have at least the basic code in common, it appears that it would have returned a kAudioUnitErr_FormatNotSupported error, had the format not been supported.
In playing sound, it definitely sounds like the conversion is not happening from 16 bit int to 32 bit float. Should it be converted in this set up?
So - do I have to feed the Default Output Unit 32 bit float data? That is, do I have to use an Audio Converter in my Audio Unit to always put out 32 bit float?
(Mac OS X 10.1.4)
Thanks,
Tracy
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