Re: render callback: To memclear or not to memclear; that is the question...
Re: render callback: To memclear or not to memclear; that is the question...
- Subject: Re: render callback: To memclear or not to memclear; that is the question...
- From: William Stewart <email@hidden>
- Date: Thu, 17 Jun 2010 11:29:34 -0700
On Jun 17, 2010, at 2:44 AM, uɐıʇəqɐz pnoqɥɒɯ wrote:
> Hi. In Apple's samples, I see that they zero out the bytes in the output buffer, like so:
>
> for (UInt32 i=0; i < inData->mNumberBuffers; i++)
> memset(inData->mBuffers[i].mData, 0, inData->mBuffers[i].mDataByteSize);
>
> What I'd like to know is whether I can accomplish the same end-result by just doing so:
>
> ioData->mBuffers[0].mDataByteSize = 0;
> with or without:
> *ioActionFlags |= kAudioUnitRenderAction_OutputIsSilence;
no
it is also good to set the silence flag though
>
> It seems to me that in the iPhoneMixerEQGraphTest sample, when the data in the source buffer isn't sufficient to satisfy the requested inNumberFrames, the following statement:
That isn't how audio units work. You are REQUIRED to provide the requested number of samples, no more and no less.
>
> if (offset < numFramesToRender) {
> numFramesToRender -= offset;
> ioData->mBuffers[0].mDataByteSize = numFramesToRender * userData->soundBuffer[inBusNumber].asbd.mBytesPerFrame;
> }
> (where numFramesToRender is a smaller number than inNumberFrames)
> seems to satisfy the caller, and no noise is heard despite the buffer being returned is smaller than requested.
>
> Am I right, or am I missing something?
>
>
> http://developer.apple.com/iphone/library/samplecode/iPhoneMixerEQGraphTest/Listings/Classes_AUGraphController_mm.html _______________________________________________
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