Re: AudioFileWriteBytes() fails with error code -40
Re: AudioFileWriteBytes() fails with error code -40
- Subject: Re: AudioFileWriteBytes() fails with error code -40
- From: Hamilton Feltman <email@hidden>
- Date: Fri, 26 Mar 2010 19:15:29 -0700
status = AudioFileWriteBytes(audioFileID, NO, 0, &numBytesToWrite,
&holdingBuffer);
This line looks suspect. holdingbufer is already a pointer and this
code is taking the address of it.
HTH,
Hamilton
On Mar 20, 2010, at 9:34 PM, Alex Wiltschko wrote:
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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