Re: how to integrate Core Audio code into the run loop
Re: how to integrate Core Audio code into the run loop
- Subject: Re: how to integrate Core Audio code into the run loop
- From: Jeff Moore <email@hidden>
- Date: Sun, 07 Sep 2008 09:06:51 -0700
Basically, it sounds like you are trying to do too much work on the
main thread. How about moving your networking code and audio playback
code to it's own work thread? That will do two good things for you.
First, your main thread (which is where AppKit does all it's work for
the most part) will be free to do UI stuff. Secondly, you'll be taking
much better advantage of the multiple CPU cores we have in our systems
these days.
On Sep 7, 2008, at 8:04 AM, John Michael Zorko wrote:
... what i've tried hasn't worked :-(
Hello, all ...
I have what is likely a very easy question. I'm new to Core Audio,
and i'm working with AudioFileStreamExample. I was quite happy to
find this, and i've learned a lot about Core Audio by seeing it
work, but the problem is that this example doesn't illustrate how to
integrate into the run loop. Basically, my app plays the audio
streamed from the server fine, but the user can't do anything else
while it's going on.
What i've done is:
1. replace the example's main() function with my own,
NSURLConnection-based code, like this:
- (void)playStream:(Song *)streamToPlay
{
NSLog(@"playing mp3 stream %s", [streamToPlay.mp3 UTF8String]);
// initialize a mutex and condition so that we can block on buffers
in use.
pthread_mutex_init(&myData.mutex, NULL);
pthread_cond_init(&myData.cond, NULL);
OSStatus err = AudioFileStreamOpen(&myData, MyPropertyListenerProc,
MyPacketsProc,
kAudioFileAAC_ADTSType, &myData.audioFileStream);
if (err)
{
NSLog(@"AudioFileOStreamOpen error %d", err);
}
NSString *url = @"http://he3.magnatune.com/all/";;
url = [url stringByAppendingString:streamToPlay.mp3];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL
URLWithString:[url
stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding]]
cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
NSURLConnection *connection = [[NSURLConnection alloc]
initWithRequest:request delegate:self];
if (connection)
{
receivedData = [[NSMutableData data] retain];
}
else
{
NSLog(@"can't connect to server");
}
}
... and inside my NSURLConnection's received-data method, I tried to
integrate into the run loop thusly:
- (void)connection:(NSURLConnection *)connection didReceiveData:
(NSData *)data
{
unsigned int length = [data length];
NSLog(@"recv'd %d bytes", length);
OSStatus status = AudioFileStreamParseBytes(myData.audioFileStream,
length, [data bytes], 0);
CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.25, false);
[receivedData appendData:data];
}
... but alas, it doesn't work -- my app is still unresponsive while
the stream is playing. I'm also not so sure that didReceiveData is
the best place to do this, but I don't know of a better place yet.
Any pointers?
--
Jeff Moore
Core Audio
Apple
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