iOS WAV to AAC ExtAudio Failing OSStatus -50 - ios

Question

In a function I am trying to convert a user-provided WAV file to AAC, however it is failing with an OSStatus of -50 when setting the client format on the output file:
OSStatus status1, status2;
// Input file
NSURL *srcUrl = [NSURL URLWithString:srcPathParam];
ExtAudioFileRef srcFile;
status1 = ExtAudioFileOpenURL((__bridge CFURLRef)srcUrl, &srcFile);
if (status1 != 0) {
NSLog(#"OSStatus: %d", (int)status1);
NSLog(#"Failed while opening src file");
ExtAudioFileDispose(srcFile);
return false;
}
// Get the source format from the file
AudioStreamBasicDescription srcFormat;
UInt32 propertySize = sizeof(AudioStreamBasicDescription);
memset(&srcFormat, 0, propertySize);
status1 = ExtAudioFileGetProperty(srcFile, kExtAudioFileProperty_FileDataFormat, &propertySize, &srcFormat);
if (status1 != 0) {
NSLog(#"OSStatus: %d", (int)status1);
NSLog(#"Failed while getting file format property from src file");
ExtAudioFileDispose(srcFile);
return false;
}
// Output format
AudioStreamBasicDescription dstFormat;
dstFormat.mFormatID = kAudioFormatMPEG4AAC;
dstFormat.mBitsPerChannel = 0;
dstFormat.mChannelsPerFrame = 2;
dstFormat.mFramesPerPacket = 1024;
dstFormat.mBytesPerPacket = 0;
dstFormat.mSampleRate = 44100;
// Output file
NSURL *dstUrl = [NSURL URLWithString:dstPathParam];
ExtAudioFileRef dstFile;
status1 = ExtAudioFileCreateWithURL((__bridge CFURLRef)dstUrl, kAudioFileAAC_ADTSType, &dstFormat, NULL, kAudioFileFlags_EraseFile, &dstFile);
if (status1 != 0) {
NSLog(#"OSStatus: %d", (int)status1);
NSLog(#"Failed while creating dst file");
ExtAudioFileDispose(srcFile);
ExtAudioFileDispose(dstFile);
return false;
}
// Create the canonical PCM client format
AudioStreamBasicDescription clientFormat;
clientFormat.mFormatID = kAudioFormatLinearPCM;
clientFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger;
clientFormat.mBitsPerChannel = 16;
clientFormat.mChannelsPerFrame = 2;
clientFormat.mFramesPerPacket = 1;
clientFormat.mBytesPerFrame = 4;
clientFormat.mBytesPerPacket = 4;
clientFormat.mSampleRate = srcFormat.mSampleRate;
// Set client data
status1 = ExtAudioFileSetProperty(srcFile, kExtAudioFileProperty_ClientDataFormat, propertySize, &clientFormat);
status2 = ExtAudioFileSetProperty(dstFile, kExtAudioFileProperty_ClientDataFormat, propertySize, &clientFormat);
The last line above it where it fails with -50, the line directly above doesn't fail however.
ExtAudioFile.cpp:700:SetClientFormat: about to throw -50: create audio converter
It's a somewhat vague error, and I'm unsure as to what this is indicating is wrong, some AudioStreamBasicDescription property on input, client, or output?

Answer 1

Setting the client data format succeeds if you fill out all the fields in dstFormat and clientFormat:
dstFormat.mFormatFlags = 0;
dstFormat.mBytesPerFrame = 0;
dstFormat.mReserved = 0;
and
clientFormat.mReserved = 0;