iOS smbPitchShift doesn't work

Question

so I'm trying to integrate the famous smbPitchShift algorithm into my project, but the input buffer and output buffer are the same. The smbPitchShift algorithm doesn't alter the samples in the buffer.

Here's what I'm doing in post-render callback:

OSStatus MyAURenderCallback (void                        *inRefCon,
                             AudioUnitRenderActionFlags  *ioActionFlags,
                             const AudioTimeStamp        *inTimeStamp,
                             UInt32                      inBusNumber,
                             UInt32                      inNumberFrames,
                             AudioBufferList             *ioData
                             )
{
    if (*ioActionFlags == kAudioUnitRenderAction_PostRender) {
        NSLog(@"render");
        SBPitchShifter *self = (__bridge SBPitchShifter *)inRefCon;

        float *fBuffer = (float *)(malloc(sizeof(float)*inNumberFrames));

        int stride = 2;
        vDSP_vflt16((SInt16 *)ioData->mBuffers[0].mData, stride, (float *)fBuffer, stride, inNumberFrames);

        smbPitchShift(2.0, inNumberFrames, inNumberFrames, 4, self.linearPCMASBD.mSampleRate, fBuffer, fBuffer);

        vDSP_vfixr16((float *)fBuffer, stride, (SInt16 *)ioData->mBuffers[0].mData, stride, inNumberFrames);

        free(fBuffer);
    }
    return noErr;
};

The sound plays just as normal, as the pitch would be set to 1. Any ideas? :)

Try to use kAudioUnitRenderAction_PreRender and set modified data to ioData buffer. — Aliaksandr Andrashuk, Feb 16 '14 at 11:18

score 1 · Accepted Answer · answered Feb 17 '14 at 13:15

1

I tried kAudioUnitRenderAction_PreRender flag as well, but it didn't work. It think I used vDSP functions from Accelerate framework wrong. I used AEFloatConverter and that did the trick ;)

answered Feb 17 '14 at 13:15

Skiny

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I'm trying to use smbPitchShift also, and am running into similar issues. Can you share (Github gist?) your updated, working, render callback? – Andrew Nov 08 '14 at 05:58

iOS smbPitchShift doesn't work

1 Answers1