iOS视频添加音乐去除原声

如果是预览视频，添加音乐这个很简单，使用AVAudioPlayer来播放音乐，目前我所做的是播放导入在工程本地的音乐文件，在线网络音乐添加尚未涉及。视频播放使用AVplayer。下面是切换背景音乐的方法：

-(void)anotherMusic:(NSURL *)url withVolume:(CGFloat)volume{_usingMusic = YES;_musicUrl = url;_musicPlayer = [[AVAudioPlayer alloc]initWithContentsOfURL:url error:nil];[_musicPlayer setVolume:volume];[_musicPlayer prepareToPlay];[_musicPlayer play];
}

我的功能基本是仿照微博发布视频做的，也有声音大小控制。一行代码控制，超级简单。

-(void)changeMusic:(CGFloat)value{
[_musicPlayer setVolume:value];
_musicVolume = value;
}
如果要关闭背景音乐，调用AVAudioPlayer 的stop方法就行。如果要控制原声：（想要静音直接将声音的值设为0）

      AVURLAsset *asset = [AVURLAsset URLAssetWithURL:_videoUrl options:nil];NSArray *audioTracks = [asset tracksWithMediaType:AVMediaTypeAudio];if(audioTracks.count>0){AVAssetTrack *assetAudioTrack = audioTracks.firstObject;audioTrack = assetAudioTrack;AVMutableAudioMixInputParameters* audioInputParams = [AVMutableAudioMixInputParameters audioMixInputParameters];[audioInputParams setVolume:value atTime:kCMTimeZero];[audioInputParams setTrackID:[assetAudioTrack trackID]];NSArray* audioParams = [NSArray arrayWithObject:audioInputParams];AVMutableAudioMix* audioMix = [AVMutableAudioMix audioMix];[audioMix setInputParameters:audioParams];[self.playItem setAudioMix:audioMix];````上面都只是预览时可见的效果，这个时候并没有真正的将你要的背景音乐加到视频中去。我们获取视频的videoTrack和audioTrack进行相应地处理合成再导出，这样才算真正的控制了视频的一切。视频原声的控制（包括音量大小或者直接静音我是写在一个方法中，方便我控制，你也可以写两个方法，静音时不加入audioTrack，但我觉得两个方法麻烦，一个方法简单点）

-(void)removeAudioTrack:(AVAsset*)asset{

self.mutableComposition = [AVMutableComposition composition];AVMutableCompositionTrack *compositionVideoTrack = [self.mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVAssetTrack *videoTrack = nil;
AVAssetTrack *assetAudioTrack = nil;
if([asset tracksWithMediaType:AVMediaTypeVideo].count!=0){videoTrack  = [[asset tracksWithMediaType:AVMediaTypeVideo]objectAtIndex:0];
}
CMTimeRange timeRange = CMTimeRangeMake(kCMTimeZero, videoTrack.timeRange.duration);
if(videoTrack!=nil){[compositionVideoTrack insertTimeRange:timeRange ofTrack:videoTrack atTime:kCMTimeZero error:nil];
}
//测试改变原声
if ([[asset tracksWithMediaType:AVMediaTypeAudio] count] != 0) {assetAudioTrack = [asset tracksWithMediaType:AVMediaTypeAudio][0];
}if (assetAudioTrack != nil) {AVMutableCompositionTrack *compositionAudioTrack = [self.mutableComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, assetAudioTrack.timeRange.duration) ofTrack:assetAudioTrack atTime:kCMTimeZero error:nil];AVMutableAudioMixInputParameters *mixParameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:compositionAudioTrack];[mixParameters setVolumeRampFromStartVolume:_sound toEndVolume:_sound timeRange:CMTimeRangeMake(kCMTimeZero,assetAudioTrack.timeRange.duration)];self.mutableAudioMix = [AVMutableAudioMix audioMix];self.mutableAudioMix.inputParameters = @[mixParameters];
}

//导出

 self.exportSession = [[AVAssetExportSession alloc] initWithAsset:[self.mutableComposition copy]  presetName:AVAssetExportPreset1280x720];
//    }self.exportSession.videoComposition = self.mutableVideoComposition;self.exportSession.audioMix = self.mutableAudioMix;self.exportSession.outputURL = [NSURL fileURLWithPath:outputURL];self.exportSession.outputFileType=AVFileTypeQuickTimeMovie;self.exportSession.shouldOptimizeForNetworkUse = YES;[self.exportSession exportAsynchronouslyWithCompletionHandler:^(void){switch (self.exportSession.status) {case AVAssetExportSessionStatusCompleted:{dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{[self writeVideoToPhotoLibrary:[NSURL fileURLWithPath:outputURL]]; });// Step 3// Notify AVSEViewController about export completion[[NSNotificationCenter defaultCenter]postNotificationName:AVSEExportCommandCompletionNotificationobject:self];}break;case AVAssetExportSessionStatusFailed:NSLog(@"导出失败：Failed:%@",self.exportSession.error);break;case AVAssetExportSessionStatusCancelled:NSLog(@"导出取消：Canceled:%@",self.exportSession.error);break;default:break;}}];添加本地音乐，传入url。-(void)addMusic:(AVAsset*)asset{CMTimeRange timeRange = CMTimeRangeMake(kCMTimeZero, [asset duration]);AVMutableCompositionTrack *customAudioTrack = [self.mutableComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];AVAssetTrack *assetAudioTrack = nil;if ([[asset tracksWithMediaType:AVMediaTypeAudio] count] != 0) {assetAudioTrack = [asset tracksWithMediaType:AVMediaTypeAudio][0];}AVAsset *audioAsset = [[AVURLAsset alloc] initWithURL:_musicUrl options:nil];AVAssetTrack *newAudioTrack = [audioAsset tracksWithMediaType:AVMediaTypeAudio][0];[customAudioTrack insertTimeRange:timeRange ofTrack:newAudioTrack atTime:kCMTimeZero error:nil];AVMutableAudioMixInputParameters *mixParameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:customAudioTrack];[mixParameters setVolumeRampFromStartVolume:_music toEndVolume:_music timeRange:CMTimeRangeMake(kCMTimeZero,asset.duration)];NSMutableArray *mut = [NSMutableArray arrayWithArray:self.mutableAudioMix.inputParameters];[mut addObject:mixParameters];self.mutableAudioMix.inputParameters = mut;

对了，上面代码还有一个需要注意的地方，如果你只调用addMusic方法，记得 self.mutableAudioMix = [AVMutableAudioMix audioMix]; 我上面的代码是音乐先调用了removeAudioTrack方法，self,mutableAudioMix被初始化过了，后面就不用再初始化了。
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