Re: (no subject)
Re: (no subject)
- Subject: Re: (no subject)
- From: Doug Wyatt <email@hidden>
- Date: Tue, 27 Jul 2004 10:28:19 -0700
On Jul 25, 2004, at 17:22, Dominic Feira wrote:
Hello.
I have been trying to get the AUHAL Audio Input example (technote:
TN2091) to work.
I have successful at receiving all silence in the AUHAL's input
callback.
I have been searching the list archives for quite some time now and
have noticed that a lot people have had the same problem. I have yet
to find a solution.
I am using a USB microphone with mono input.
It is using the following ABSDs for the conversion (to/from) :
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Sample Rate:8000.000000
Format ID:lpcm
Format Flags:B
Bytes per Packet:4
Frames per Packet:1
Bytes per Frame:4
Channels per Frame:1
Bits per Channel:32
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mono packed big-endian float ... OK
- - - - - - - - - - - - - - - - - - - -
Sample Rate:8000.000000
Format ID:lpcm
Format Flags:6
Bytes per Packet:4
Frames per Packet:1
Bytes per Frame:4
Channels per Frame:1
Bits per Channel:16
- - - - - - - - - - - - - - - - - - - -
Strictly correct would be format flags of kAudioFormatFlagIsPacked |
kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsBigEndian (14),
though the converter may be tolerating the packed flag being set, I
can't remember off the top of my head.
More problematic is that you've said that bits per channel is 16, which
means that (since channels per frame is 1), you probably want 2 bytes
per packet and 2 bytes per frame. Right now you're telling it you want
16 bit integers aligned low in 32 bit (4 byte) sample words.
Doug
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| | >(no subject) (From: Dominic Feira <email@hidden>) |