Newbie: trying to log samples
Newbie: trying to log samples
- Subject: Newbie: trying to log samples
- From: Michael Hanna <email@hidden>
- Date: Thu, 3 Feb 2005 01:55:07 -0500
hi, I'm trying to log the samples coming from the microphone. This code
is from the net that uses the MTCoreAudio. buffer->mDataByteSize %u
gives me 4096 bytes, so I'm assuming that I'm being fed 4096 bytes, or
2048 samples per cycle(each sample being 2 bytes long, or 16-bit).
I added the unsigned char aSample[2] (want to see if I can get the
first sample out of the buffer as a starting point). Then once the data
is read-in, I memcpy the first sample to the aSample array. Then I log
it to the console as an unsigned 16-bit. However my output is the same
over and over:
2005-02-03 01:44:45.577 Recordotron[4074] aSample 5392
2005-02-03 01:44:45.588 Recordotron[4074] aSample 5392
2005-02-03 01:44:45.600 Recordotron[4074] aSample 5392
Clearly I'm not doing something right, but I'm not sure what! :)
Any help at all would be appreciated.
Michael
- (OSStatus) readCycleForDevice: (MTCoreAudioDevice *) theDevice
timeStamp: (const AudioTimeStamp *) now
inputData: (const AudioBufferList *) inputData
inputTime: (const AudioTimeStamp *) inputTime
outputData: (AudioBufferList *) outputData
outputTime: (const AudioTimeStamp *) outputTime
clientData: (void *) clientData
{
unsigned char aSample[2];
// peer into the data
const AudioBuffer *buffer;
buffer = &inputData->mBuffers[0];
//NSLog(@"buffer->mDataByteSize %u", buffer->mDataByteSize);
// will this sample put us over the line? If so, dump the data
// and tell the UI to stop the recording and disable the Stop
// button. We don't stop the actual reading from here
// because it seems to leave some stale locks in the MTCoreAudio
// guts.
if (g_lastIndex + buffer->mDataByteSize > SOUND_BUFFER_SIZE) {
[self performSelectorOnMainThread: @selector(stopRecording:)
withObject: self
waitUntilDone: NO];
} else {
memcpy (aSample + 2, buffer->mData, 2); // grab 2 bytes(one sample)
NSLog(@"aSample %hi", aSample); // output as an unsigned 16-bit
integer
// append the data to the end of our buffer
memcpy (g_soundBuffer + g_lastIndex,
buffer->mData, buffer->mDataByteSize);
g_lastIndex += buffer->mDataByteSize;
}
return (noErr);
} // readCycleForDevice
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