alBufferDataStatic instead of alBufferData

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Posts: 345
Joined: 2002.04

Post: #1

Jan 23, 2009 — 03:18 AM

According to Tech Note TN2199 it is better to use alBufferDataStatic instead if alBufferData for sound on the iPhone. However even when I import OpenAL/oalStaticBufferExtension.h the function is undeclared. Has anyone else experienced this?

Slope Rider | Twit

AnotherJake

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Post: #2

Jan 23, 2009 — 09:42 AM

Yes, it is super funky to figure it out. Look closely at what they're doing with alBufferDataStaticProc in the oalTouch sample. ... Funky!

AnotherJake

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Post: #3

Jan 23, 2009 — 09:47 AM

Actually, the way they do it is kind of dramatic. Here's what I do:

Code:

// retrieve the static buffer function

alBufferDataStaticProcPtr    alBufferDataStaticProc = (alBufferDataStaticProcPtr)alcGetProcAddress(nil, (const ALCchar *)"alBufferDataStatic");

// buffer the data

alBufferDataStaticProc(bufferID, bitChanFormat, audioData, audioDataSize, dataFormat.mSampleRate);

monteboyd

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Posts: 345
Joined: 2002.04

Post: #4

Jan 23, 2009 — 09:57 AM

That's great, thanks AnotherJake. I'd had a quick look at oalTouch example and was a bit confused!

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kordos

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Posts: 6
Joined: 2009.01

Post: #5

Feb 15, 2009 — 10:37 AM

Pardon my ignorance, but I've replaced my calls to alBufferData() with alBufferDataStaticProc(), and I'm getting some very unpleasant results.

The sequence is more or less:

Code:

        NSUInteger bufferID;

        alGenBuffers(1, &bufferID);

        error = alGetError(); 

        if (error) NSLog(@"    alGenBuffers got alGetError():  %d\n\n", error);

//alBufferData(bufferID,AL_FORMAT_STEREO16,outData,fileSize,44100);

        alBufferDataStaticProcPtr    alBufferDataStaticProc = (alBufferDataStaticProcPtr)alcGetProcAddress(nil, (const ALCchar *)"alBufferDataStatic");

        alBufferDataStaticProc(bufferID, AL_FORMAT_STEREO16, outData, fileSize, 44100);

        error = alGetError(); 

        if (error) NSLog(@"    alBufferData got alGetError():  %d\n\n", error);

        // save the buffer so I can release it later

        [bufferStorageArray addObject:[NSNumber numberWithUnsignedInteger:bufferID]];

        // grab a source ID from openAL

        UInt32 sourceID;

        alGenSources(1, &sourceID);

        error = alGetError(); 

        if (error) NSLog(@"    alGenSources got alGetError():  %d\n\n", error);

        // attach the buffer to the source

        alSourcei(sourceID, AL_BUFFER, bufferID);

        alSourcef(sourceID, AL_GAIN, 1.0f);

With alBufferData it works perfectly, but with alBufferDataStaticProc, the sound is horrendous on playback. Do I need to do something to retain the buffer?

AnotherJake

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Posts: 3,552
Joined: 2003.06

Post: #6

Feb 15, 2009 — 12:27 PM

I don't see anything poking out except that you're manually inputing the audio format and sample rate. I get the format using:

Code:

size = sizeof(dataFormat);

AudioFileGetProperty(audioFile, kAudioFilePropertyDataFormat, &size, &dataFormat);

And use the values from that.

Still, you'd think that if a given file worked for you using alBufferData, it should work exactly the same with alBufferDataStaticProc. Weird.

monteboyd

Member

Posts: 345
Joined: 2002.04

Post: #7

Feb 16, 2009 — 04:12 AM

Actually, I had a similar problem. Try AnotherJake's solution first as that might work and is simpler, but what I did was to use the oalTouch sample's loading code and that solved whatever problem was causing the distorted sound.

Slope Rider | Twit

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