音频剪切

1.音频剪切比较简单传入音频文件和剪切的时间段就可以了

/** 初始化输出文件路径 */NSString *url = "音频源文件路径";NSString *outPutPath = "音频前切完成输出文件路径";NSURL *audioFileOutput = [NSURL fileURLWithPath:outPutPath];[[NSFileManager defaultManager] removeItemAtURL:audioFileOutput error:NULL];/** 初始化要剪切的音频文件 */AVAsset *asset = [AVAsset assetWithURL:url];AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:assetpresetName:AVAssetExportPresetAppleM4A];/** 剪切的时间段 */CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTime, endTime);exportSession.outputURL = audioFileOutput;exportSession.outputFileType = AVFileTypeAppleM4A;exportSession.timeRange = exportTimeRange;[exportSession exportAsynchronouslyWithCompletionHandler:^{if (AVAssetExportSessionStatusCompleted == exportSession.status) {NSLog(@" FlyElephant \n %@", outPutPath);} else if (AVAssetExportSessionStatusFailed == exportSession.status) {NSLog(@"FlyElephant error: %@", exportSession.error.localizedDescription);}}];
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音频的合成

1.音频的合成这里的背景是有一段录音需要加一个背景音乐,视频合成的也是一样的道理把音频源文件改成视频，然后相应的配置改成文件就好了。

    NSString *exportPath = @"导出文件路径";NSString *url = @"音频源文件路径";//音频来源路径NSURL *audioUrl = [NSURL fileURLWithPath:url];NSURL *backPathUrl = [NSURL fileURLWithPath:backPath];//导出路径NSURL *exporAudiotPath = [NSURL fileURLWithPath:exportPath];//删除相同导出路径的文件unlink([exportPath UTF8String]);//创建可变的音频视频组合AVMutableComposition *mixComposition = [AVMutableComposition composition];/** 初始化音频 */AVURLAsset *audioAsset = [[AVURLAsset alloc] initWithURL:audioUrl options:nil];AVURLAsset *audioBack = [[AVURLAsset alloc] initWithURL:backPathUrl options:nil];/** 音乐的时间 */CMTimeRange audio_timeRange = CMTimeRangeMake(kCMTimeZero,audioAsset.duration);//获取视频或者音频中的音频轨道AVAssetTrack *audioTrack = [[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];AVAssetTrack *audioBackTrack = [[audioBack tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];//可变音视频轨道添加一个 音频通道AVMutableCompositionTrack *audioCompositionTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];AVMutableCompositionTrack *audioCompositionBackTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];//插入音频到容器[audioCompositionTrack insertTimeRange:audio_timeRange ofTrack:audioTrack atTime:kCMTimeZero error:nil];[audioCompositionBackTrack insertTimeRange:audio_timeRange ofTrack:audioBackTrack atTime:kCMTimeZero error:nil];//初始化音频混合器AVMutableAudioMix *exportAudioMix = [AVMutableAudioMix audioMix];//获取到第二条音轨并且设置他的音量大小AVAssetTrack *mixCompositionTrack = [[mixComposition tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:1];//初始化音频混合器导出配置参数AVMutableAudioMixInputParameters *exportAudioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:mixCompositionTrack];/** 设置第二条音轨的背景音效声音大小 */[exportAudioMixInputParameters setVolumeRampFromStartVolume:0 toEndVolume:[AVAudioSession sharedInstance].outputVolume * 0.6 timeRange:audio_timeRange];NSArray *audioMixParameters = @[exportAudioMixInputParameters];exportAudioMix.inputParameters = audioMixParameters;//创建一个输出AVAssetExportSession* assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetAppleM4A];/** 导出文件的地址 */assetExport.outputURL = exporAudiotPath;/** 导出文件的格式 */assetExport.outputFileType = @"com.apple.m4a-audio";/** 网络优化 */assetExport.shouldOptimizeForNetworkUse = YES;assetExport.audioMix = exportAudioMix;[assetExport exportAsynchronouslyWithCompletionHandler:^(void ) {NSLog(@"$$$");NSLog(@"完成！输出路径==%@",exportPath);if(completion)completion(exportPath);}];
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音频的淡入淡出

1.音频的淡入只需要设置音频音轨开始的音量从0到正常的音量，淡出只需要设置音轨音量从淡出时间到结束从正常音量到0就行了。

    NSString *exportPath = @"音频导出文件路径";NSString *exportPath = @"音频源文件路径";//淡入时间NSInteger fadeInTime = 5;//淡出时间NSInteger fadeOutTime = 5;//音频来源路径NSURL *audioUrl = [NSURL fileURLWithPath:url];//导出路径NSURL *exporAudiotPath = [NSURL fileURLWithPath:exportPath];//删除相同导出路径的文件unlink([exportPath UTF8String]);//初始化开始时间CMTime nextClipStartTime = kCMTimeZero;//创建可变的音频视频组合AVMutableComposition *mixComposition = [AVMutableComposition composition];//初始化音频文件AVURLAsset  *audioAsset = [[AVURLAsset alloc] initWithURL:audioUrl options:nil];/** 获取音频时长 */CMTimeRange audioTimeRange = CMTimeRangeMake(kCMTimeZero,audioAsset.duration);//创建一个输出AVAssetExportSession* assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetAppleM4A];assetExport.outputURL = exporAudiotPath;assetExport.outputFileType = @"com.apple.m4a-audio";assetExport.shouldOptimizeForNetworkUse = YES;//获取音频文件中的音频轨道AVAssetTrack *audioTrack = [[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];//初始化一个音频容器AVMutableCompositionTrack *audioCompositionTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];//插入音频到容器[audioCompositionTrack insertTimeRange:audioTimeRange ofTrack:audioTrack atTime:nextClipStartTime error:nil];//初始化音频混合器AVMutableAudioMix *exportAudioMix = [AVMutableAudioMix audioMix];//获取混合后的音轨AVAssetTrack *mixCompositionTrack = [[mixComposition tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];//初始化音频混合器导出配置参数AVMutableAudioMixInputParameters *exportAudioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:mixCompositionTrack];//初始化淡入淡出持续时间  这个可以根据项目需求来设置这里前5秒淡入音量从0到1.0，最后5秒淡出音量从1.0到0 大家可以根据自己需求修改/** 获取当前的音频 */CGFloat volume = [AVAudioSession sharedInstance].outputVolume;if(fadeInTime > 0){//        设置前5秒音乐淡入CMTime continueFadeInTime = CMTimeMakeWithSeconds(fadeInTime, 1);[exportAudioMixInputParameters setVolumeRampFromStartVolume:0 toEndVolume:volume timeRange:CMTimeRangeMake(CMTimeMakeWithSeconds(0, 1), continueFadeInTime)];}if(fadeOutTime > 0){//        计算开始淡出的时间CMTime continueFadeOutTime = CMTimeMakeWithSeconds(fadeOutTime, 1);CMTime fadeOutStartTime = CMTimeSubtract(audioAsset.duration, continueFadeOutTime);//        设置最后5秒音乐淡出[exportAudioMixInputParameters setVolumeRampFromStartVolume:volume toEndVolume:0 timeRange:CMTimeRangeMake(fadeOutStartTime, continueFadeOutTime)];}//        设置音频混合器参数NSArray *audioMixParameters = @[exportAudioMixInputParameters];exportAudioMix.inputParameters = audioMixParameters;//添加到导出配置中assetExport.audioMix = exportAudioMix;//开始导出[assetExport exportAsynchronouslyWithCompletionHandler:^(void ) {NSLog(@"$$$");NSLog(@"完成！输出路径==%@",exportPath);if(completion)completion(exportPath);}];
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