IPhone (SDK 6): AudioQueue still wonky-can't play mp3

Question

I have an mp3 streaming app up and running (sortof).
Initially I set things up in "VBR" mode, which requires supplying packet descriptions for each frame supplied to the queue. That worked (??). Mostly. I was getting some dropouts and other flaky behaviour, but it gave me something to demo.
Note that this is a CBR stream. So then I set up things to handle CBR, which is much simpler.
So I have a call similar to this:
status=AudioQueueEnqueueBuffer(inAQ, inCompleteAQBuffer,0, NULL);
This does not work. My connectLoop is as follows taken from the audio queue example code:
do
loopError=CFRunLoopRunInMode(kCFRunLoopDefaultMode,0.25,false);
}while(!m_myInfo.mDone);
When working, my audio callback routine is regularly called when the queue is ready for more data. When it is not working using the CBR approach the callback is NEVER called. It is as if somewhere along the line it gets gummed up, or is not initialized properly, even though the CBR method is less involved so should be harder to make mistakes.
Is there any gotcha here that is easy to overlook? The format data is retrieved from a call to to AudioFileGetProperty(), also per the example. So in theory, that should be all I need.
Any ideas?

Answer 1

Hi, here is what I have got so far with regards to streaming and playing an MP3..
I hope it helps some people, and I hope some people can help me!
First, I define a custom data structure to hold stuff throughout..
typedef struct {
AudioFileStreamID audioFileStream;
AudioStreamBasicDescription mDataFormat;
AudioQueueRef mQueue;
CFReadStream readStream;
UInt32 mNumPackets;
AudioStreamPacketDescription *mPacketDescs;
} CustomData;
CustomData customData;
I also set up an AudioQueue with a callback..
AudioQueueNewOutput(&customData.mDataFormat,
AudioOutputCallBack,
&customData,
NULL,
kCFRunLoopCommonModes,
0,
&customData.mQueue);
I set up an AudioFileStream..
AudioFileStreamOpen(0,
audioFileStream_Properties,
audioFileStream_Packets,
kAudioFileMP3Type,
&customData.audioFileStream);
..this has call back functions attached when the AudioFileStream receives either stream properties or stream packets..
I then open a data stream to a URL of an MP3 stream..
NSURL *url = [NSURL URLWithString:@"http://mp3stream.com"];
CFHTTPMessageRef message = CFHTTPMessageCreateRequest(kCFAllocatorDefault,
CFSTR("GET"),
(CFURLRef)url,
kCFHTTPVersion1_1);
customData.readStream = CFReadStreamCreateForHTTPRequest(kCFAllocatorDefault, message);
CFOptionFlags events = kCFStreamEventHasBytesAvailable | kCFStreamEventErrorOccured | kCFStreamEventEndEncountered;
CFStreamClientContext dataStreamContext = {0, self, NULL, NULL, NULL};
if (CFReadStreamSetClient(customData.readStream, events, readStreamEventCallBack, &dataStreamContext)) {
CFReadStreamScheduleWithRunLoop(customData.readStream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
CFReadStreamOpen(customData.readStream);
..this opens a CFReadStream with a call back function that is called on bytes available events, error events and end events..
void readStreamEventCallBack(CFReadStreamRef stream, CFStreamEventType eventType, void *clientcallBackInfo) {
switch(eventType) {
case kCFStreamEventHasBytesAvailable:
UInt8 buf[4096];
CFIndex bytesRead = CFReadStreamRead(stream, buf, 4096);
if (bytesRead > 0) {
AudioFileStreamParseBytes(customData.audioFileStream, bytesRead, buf, 0);
case kCFStreamEventErrorOccurred:
//do stuff
break;
case kCFStreamEventEndOccurred:
//do stuff
break;
So when the CFReadStream reads some bytes it passes them to the AudioFileStream which will in turn call its callback functions when it receives stream properties or stream packets..
In audioFileStream_Properties I attempt to get the dataFormat of the stream..
void audioFileStream_Properties (void *inClientData,
AudioFileStreamID inAudioFileStream,
AudioFileStreamPropertyID inPropertyID,
UInt32 *ioFlags) {
if (inPropertyID == kAudioFileStreamProperty_DataFormat) {
UInt32 size;
AudioFileStreamGetPropertyInfo(inAudioFileStream, inPropertyID, &size, nil)
AudioFileStreamGetProperty(inAudioFileStream, inPropertyID, &size, &customData.mDataFormat);
Most of these function calls return an OSStatus which should be checked for error (!= 0) but I have left them out for now..
Then the AudioFileStream packets..
void audioFileStream_Packets (void *inClientData,
UInt32 inNumberBytes,
UInt32 inNumberPackets,
const void *inInputData,
AudioStreamPacketDescription *inPacketDescs) {
customData.mNumPackets = inNumberPackets;
customData.mPacketDescs = inPacketDescs;
AudioQueueBufferRef outBuffer;
AudioQueueAllocateBuffer(customData.mQueue, inNumberBytes, &outBuffer);
AudioOutputCallBack(&customData, customData.mQueue, outBuffer);
..here I try and allocate the stream packets into the an AudioQueueBuffer and force that buffer into the AudioQueue callback..
static void AudioOutputCallBack(void *inCustomData,
AudioQueueRef outAQ,
AudioQueueBufferRef) {
CustomData *customData = (CustomData*)inCustomData;
AudioQueueEnqueueBuffer(customData->mQueue, outBuffer, (customData->mPacketDescs ? customData->mNumPackets : 0), playState->mPacketDescs);
..Now, I would hope this would be queuing buffers up ready to play! However,
AudioQueueEnqueueBuffer returns error 1718449215 - I am not sure what this means, I am led to believe it might be a dataFormat error
Hope everyone call follow!
Adam
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