updated internalRenderBlock

VolumePluginAudioUnit.m

- (AUInternalRenderBlock)internalRenderBlock {
    // Capture in locals to avoid ObjC member lookups. If "self" is captured in render, we're doing it wrong. See sample code.
    __block Buffer* buffer = &_buffer;
    
    return ^AUAudioUnitStatus(AudioUnitRenderActionFlags *actionFlags, const AudioTimeStamp *timestamp, AVAudioFrameCount frameCount, NSInteger outputBusNumber, AudioBufferList *outputData, const AURenderEvent *realtimeEventListHead, AURenderPullInputBlock pullInputBlock) {
        // Do event handling and signal processing here.
        AudioUnitRenderActionFlags pullFlags = 0;
        buffer->prepareInputBufferList();
        AUAudioUnitStatus err = pullInputBlock(&pullFlags, timestamp, frameCount, 0, buffer->mutableAudioBufferList);
        
        if (err != 0) {
            NSLog(@"borama VolumePluginAudioUnit AudioUnitRenderActionFlags");
            return err;
        }
        
        AudioBufferList *inAudioBufferList = buffer->mutableAudioBufferList;
        AudioBufferList *outAudioBufferList = outputData;
        
        // If passed null output buffer pointers, process in-place in the input buffer.
        if (outAudioBufferList->mBuffers[0].mData == nullptr) {
            for (UInt32 i = 0; i < outAudioBufferList->mNumberBuffers; ++i) {
                outAudioBufferList->mBuffers[i].mData = inAudioBufferList->mBuffers[i].mData;
            }
        }
        
        UInt32 samplesCount = inAudioBufferList->mBuffers[0].mDataByteSize / sizeof(float);
        
        for (int j = 0; j < inAudioBufferList->mNumberBuffers; j++) {
            float* input = (float*)inAudioBufferList->mBuffers[j].mData;
            float* output = (float*)outAudioBufferList->mBuffers[j].mData;
            // the might be more than one channel (stereo)
            for (int i = 0; i < samplesCount; i++) {
                output[i] = buffer->volume * input[i];
            }
        }
        
        return noErr;
    };
}