AudioFileWriteBytes() fails with error code -40
AudioFileWriteBytes() fails with error code -40
- Subject: AudioFileWriteBytes() fails with error code -40
- From: Alex Wiltschko <email@hidden>
- Date: Sun, 21 Mar 2010 00:34:01 -0400
I'm trying to write raw audio bytes to a file using AudioFileWriteBytes(). I get an error of "-40".
This is a function I'm calling from an NSTimer, after properly initializing the audio file. Here's what I'm doing:
void writeSingleChannelRingBufferDataToFileAsSInt16(AudioFileID audioFileID, AudioConverterRef audioConverter, ringBuffer *rb, SInt16 *holdingBuffer) {
// First, figure out which bits of audio we'll be
// writing to file from the ring buffer
UInt32 lastFreshSample = rb->lastWrittenIndex;
OSStatus status;
int numSamplesToWrite;
UInt32 numBytesToWrite;
if (lastFreshSample < rb->lastReadIndex) {
numSamplesToWrite = kNumPointsInWave + lastFreshSample - rb->lastReadIndex - 1;
}
else {
numSamplesToWrite = lastFreshSample - rb->lastReadIndex;
}
numBytesToWrite = numSamplesToWrite*sizeof(SInt16);
// Then I copy the audio data (stored as floats) to a holding buffer (SInt16)
// that will be written directly to the file.
// The copying looks funky because it's from a ring buffer.
UInt32 buffLen = rb->sizeOfBuffer - 1;
for (int i=0; i < numSamplesToWrite; ++i) {
holdingBuffer[i] = rb->data[(i + rb->lastReadIndex) & buffLen];
}
// Okay, now we actually try to write the audio from the SInt16 buffer "holdingBuffer"
// to the audio file. The NSLog will spit out an error -40,
// but also claims that it's writing bytes. No data is written to file.
status = AudioFileWriteBytes(audioFileID, NO, 0, &numBytesToWrite, &holdingBuffer);
rb->lastReadIndex = lastFreshSample;
NSLog(@"Error = %d, wrote %d bytes", status, numBytesToWrite);
return;
What is this error -40? By the way, everything works fine if I write straight from the ringBuffer to the file. Of course, when I play the AIF file, it sounds like junk, because I'm writing floats, not SInt16s, but AudioFileWriteBytes doesn't complain. _______________________________________________
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