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Question about output data streaming
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Question about output data streaming


  • Subject: Question about output data streaming
  • From: "David Tan" <email@hidden>
  • Date: Wed, 7 Jan 2009 23:57:54 +0800

Hi List,

 

I got a general question about the data streaming of

IOAudioEngine::clipOutputSamples(const void *inMixBuf, void *sampleBuf, UInt32 firstSampleFrame, UInt32 numSampleFrames, const IOAudioStreamFormat *streamFormat, IOAudioStream *audioStream)

 

Please correct me if there’s any misunderstanding of this method.

 

Firstly I generate a binary file with data from value 0 to 65535. Then I used Audacity to convert this raw data file to a wave file. I checked the wave in Audacity and it looks like an ascending incline. While playing this WAV file, these data will be transmitted to kernel driver via CoreAudio. What we get in kernel audio driver will be float data in inMixBuf (firstSampleFrame indicate the first valid data we should process in it). We should convert these float data into integer data before we send them to the device. After the conversion completes, we’ll get actual integer data 0-65535.

 

Is that correct? Thanks a lot!

 

Sincerely yours,

David Tan

Dextrys Co., Ltd.

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