SoundTouchAVAssetPlayer.mm

//
// Copyright 2011 Mike Coleman
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Note: You are NOT required to make the license available from within your
// iOS application. Including it in your project is sufficient.
//
// Attribution is not required, but appreciated :)
//

#import "SoundTouchAVAssetPlayer.h"
#include <SoundTouch/SoundTouch.h>

@interface SoundTouchAVAssetPlayer() {
    soundtouch::SoundTouch soundTouchEngine;
}
- (void)setupSoundTouch;

@end

@implementation SoundTouchAVAssetPlayer

- (id)init {
    self = [super init];
    if (self) {
        [self setupSoundTouch];
        self.filteringCallback = ^(AudioAssetPlayer *player, char *srcBuffer, UInt32 srcBytesAvailable, char *dstBuffer, UInt32 dstBufferCapacity, UInt32 *dstBytesWritten) {
            soundTouchEngine.setTempoChange(tempo);
            soundTouchEngine.putSamples((soundtouch::SAMPLETYPE *)srcBuffer, srcBytesAvailable / 4);
            UInt32 samplesWritten = soundTouchEngine.receiveSamples((soundtouch::SAMPLETYPE *)dstBuffer, 32768 / 4);
            *dstBytesWritten = samplesWritten * 4;
        };
    }

    return self;
}

- (float)tempo {
    return tempo;
}

- (void)setTempo:(float)aTempo {
    if (aTempo < -95.0f) {
        aTempo = -95.0f;
    }
    else if (aTempo > 5000.0f) {
        aTempo = 5000.0f;
    }
    tempo = aTempo;
    soundTouchEngine.setTempoChange(tempo);
}

- (void)setupSoundTouch {
    int sampleRate = 44100;
    int channels = 2;
    soundTouchEngine.setSampleRate(sampleRate);
    soundTouchEngine.setChannels(channels);
    soundTouchEngine.setTempoChange(0.0f);
    soundTouchEngine.setPitchSemiTones(0.0f);
    soundTouchEngine.setRateChange(0.0f);
    soundTouchEngine.setSetting(SETTING_USE_QUICKSEEK, TRUE);
    soundTouchEngine.setSetting(SETTING_USE_AA_FILTER, FALSE);
}

- (void)stop {
    soundTouchEngine.clear();
    [super stop];
}

@end