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Basic AudioStreamBasicDescription question
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Basic AudioStreamBasicDescription question


  • Subject: Basic AudioStreamBasicDescription question
  • From: "Mike Kluev" <email@hidden>
  • Date: Thu, 11 Dec 2008 21:05:58 +0300

Hi folks,

1) I've got the following sample description from OS:
AudioStreamBasicDescription:
	.mSampleRate == 44100;
	.mFormatID == 'lpcm';
	.mFormatFlags == 0x29; // float, packed, non interleaved
	.mBytesPerPacket == 4;
	.mFramesPerPacket == 1;
	.mBytesPerFrame == 4;
	.mChannelsPerFrame == 2;
	.mBitsPerChannel == 32;
	.mReserved == 0;

Focusing on:

	.mBytesPerFrame == 4;
	.mChannelsPerFrame == 2;
	.mBitsPerChannel == 32;

How could this be true?
In particular: if channels/frame == 2 and bits/channel == 32 then I'd expect
bits/frame to be 64, so bytes/frame should be 8, yet it 4. And vice versa.


2) Is FillOutASBDForLPCM (and CalculateLPCMFlags) API reliable? I do not see how to
instruct it to give me the above result (provided the above result is somehow valid).


Mike

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