iOS AVFoundation音频 混合、拼接、播放音量设置

音频 混合-拼接代码段
-(void)addAudioPath1:(NSURL *)firstPath andAudioPath2:(NSURL *)secondPath {
// 第一个音频内容
AVAsset * firstAudioAsset = [AVAsset assetWithURL:firstPath];

// 第二个音频内容
AVAsset * secondAudioAsset = [AVAsset assetWithURL:secondPath];

// 创建可变的音频视频组合 音频组合 音视频组合 视频组合都使用这个
AVMutableComposition *mixComposition = [AVMutableComposition composition];

// 第一个音频轨道
AVMutableCompositionTrack *firstAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

// 第一个音频asset添加到轨道，第一个音频内容添加到firstAudioTrack轨道中
// 参数1：时间0-firstAudioAsset音频的持续时间
// 参数2：AVAssetTrack类型的内容
// 参数3：开始时间
[firstAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, firstAudioAsset.duration) ofTrack:[firstAudioAsset tracksWithMediaType:AVMediaTypeAudio].firstObject atTime:kCMTimeInvalid error:nil];

// 第二个音频轨道
AVMutableCompositionTrack *secondAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

//第二个音频asset添加到轨道，开始时间不同就决定了音频混合或者拼接
// atTime:kCMTimeInvalid 混音 音频1和音频2 同时播放
// atTime:firstAudioAsset.duration 拼接 音频2的播放在音频1结束以后开始
[secondAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, secondAudioAsset.duration) ofTrack:[secondAudioAsset tracksWithMediaType:AVMediaTypeAudio].firstObject atTime:kCMTimeInvalid error:nil];

NSLog(@"%@", [secondAudioAsset tracksWithMediaType:AVMediaTypeAudio].firstObject);


//修改背景音乐的音量start
AVMutableAudioMix *videoAudioMixTools = [AVMutableAudioMix audioMix];
NSMutableArray * params = [[NSMutableArray alloc] initWithCapacity:0];
if (firstAudioAsset) {
    //调节音量
    //获取音频轨道
    AVMutableAudioMixInputParameters *firstAudioParam = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:firstAudioTrack];
    //设置音轨音量,可以设置渐变,设置为1.0就是全音量
    [firstAudioParam setVolumeRampFromStartVolume:0.05 toEndVolume:1.0 timeRange:CMTimeRangeMake(kCMTimeZero, firstAudioAsset.duration)];
    [firstAudioParam setTrackID:firstAudioTrack.trackID];
    [params addObject:firstAudioParam];
}

if (secondAudioAsset) {
    //调节音量
    //获取音频轨道
    AVMutableAudioMixInputParameters *secondAudioParam = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:secondAudioTrack];
    //设置音轨音量,可以设置渐变,设置为1.0就是全音量
    [secondAudioParam setVolumeRampFromStartVolume:0.1 toEndVolume:1.0 timeRange:CMTimeRangeMake(kCMTimeZero, secondAudioAsset.duration)];
    [secondAudioParam setTrackID:secondAudioTrack.trackID];
    [params addObject:secondAudioParam];
}

videoAudioMixTools.inputParameters = [NSArray arrayWithArray:params];

//end


//导出音频
AVAssetExportSession *session = [[AVAssetExportSession alloc]initWithAsset:mixComposition presetName:AVAssetExportPresetAppleM4A];
NSString * outputPath = [self getAudioPath];
self.saveAudioPath = outputPath;

// 千万注意 fileURLWithPath
session.outputURL = [NSURL fileURLWithPath:outputPath];
session.outputFileType = AVFileTypeAppleM4A;
session.shouldOptimizeForNetworkUse = YES;
session.audioMix = videoAudioMixTools;

//导出之前先删除之前旧文件
//导出是否成功回调
[session exportAsynchronouslyWithCompletionHandler:^{
    NSLog(@"exportSession.status == %ld", (long)session.status);
    if (session.status == AVAssetExportSessionStatusCompleted) {
        NSLog(@"音频拼接成功");
        [self playAudio];
    } else {
        NSLog(@"音频拼接失败");
    }
}];

}

-(void)playAudio {
if (!self.musicPlayer) {
NSURL *fileUrl = [NSURL URLWithString:self.saveAudioPath];
self.musicPlayer = [[AVAudioPlayer alloc]initWithContentsOfURL:fileUrl error:nil];
}

if (![self.musicPlayer isPlaying]){
    [self.musicPlayer setVolume:1.0];
    [self.musicPlayer prepareToPlay];
    [self.musicPlayer play];
}

}