//抽取原視頻的音頻與需要的音樂混合 -(void)addmusic:(id)sender {  [MBProgressHUDshowHUDAddedTo:self.viewanimated:YES];  AVMutableComposition *composition =[AVMutableCompositioncomposition];  audioMixParams =[[NSMutableArrayalloc]initWithObjects:nil];  //錄制的視頻  NSURL *video_inputFileUrl =[NSURLfileURLWithPath:self.videoPath];  AVURLAsset *songAsset =[AVURLAssetURLAssetWithURL:video_inputFileUrloptions:nil];  CMTime startTime =CMTimeMakeWithSeconds(0,songAsset.duration.timescale);  CMTime trackDuration =songAsset.duration;  //獲取視頻中的音頻素材  [selfsetUpAndAddAudioAtPath:video_inputFileUrltoComposition:compositionstart:startTimedura:trackDurationoffset:CMTimeMake(14*44100,44100)];  //本地要插入的音樂  NSString *bundleDirectory =[[NSBundlemainBundle]bundlePath];  NSString *path = [bundleDirectorystringByAppendingPathComponent:@"30secs.mp3"];  NSURL *assetURL2 =[NSURLfileURLWithPath:path];  //獲取設置完的本地音樂素材  [selfsetUpAndAddAudioAtPath:assetURL2toComposition:compositionstart:startTimedura:trackDurationoffset:CMTimeMake(0,44100)];  //創建一個可變的音頻混合  AVMutableAudioMix *audioMix =[AVMutableAudioMixaudioMix];  audioMix.inputParameters =[NSArrayarrayWithArray:audioMixParams];//從數組里取出處理后的音頻軌道參數  //創建一個輸出  AVAssetExportSession *exporter =[[AVAssetExportSessionalloc]         initWithAsset:composition         presetName:AVAssetExportPresetAppleM4A];  exporter.audioMix = audioMix;  exporter.outputFileType=@"com.apple.m4a-audio";  NSString* fileName =[NSStringstringWithFormat:@"%@.mov",@"overMix"];  //輸出路徑  NSString *exportFile =[NSStringstringWithFormat:@"%@/%@",[selfgetLibarayPath], fileName];  if([[NSFileManagerdefaultManager]fileExistsAtPath:exportFile]) {   [[NSFileManagerdefaultManager]removeItemAtPath:exportFileerror:nil];  }  NSLog(@"是否在主線程1%d",[NSThreadisMainThread]);  NSLog(@"輸出路徑===%@",exportFile);  NSURL *exportURL =[NSURLfileURLWithPath:exportFile];  exporter.outputURL = exportURL;  self.mixURL =exportURL;  [exporterexportAsynchronouslyWithCompletionHandler:^{   int exportStatus =(int)exporter.status;   switch (exportStatus){    caseAVAssetExportSessionStatusFailed:{     NSError *exportError =exporter.error;     NSLog(@"錯誤，信息: %@", exportError);     [MBProgressHUDhideHUDForView:self.viewanimated:YES];     break;    }    caseAVAssetExportSessionStatusCompleted:{     NSLog(@"是否在主線程2%d",[NSThreadisMainThread]);     NSLog(@"成功");     //最終混合     [selftheVideoWithMixMusic];     break;    }   }  }]; } //最終音頻和視頻混合 -(void)theVideoWithMixMusic {  NSError *error =nil;  NSFileManager *fileMgr =[NSFileManagerdefaultManager];  NSString *documentsDirectory =[NSHomeDirectory()         stringByAppendingPathComponent:@"Documents"];  NSString *videoOutputPath =[documentsDirectorystringByAppendingPathComponent:@"test_output.mp4"];  if ([fileMgrremoveItemAtPath:videoOutputPatherror:&error]!=YES) {   NSLog(@"無法刪除文件，錯誤信息：%@",[error localizedDescription]);  }  //聲音來源路徑（最終混合的音頻）  NSURL *audio_inputFileUrl =self.mixURL;  //視頻來源路徑  NSURL *video_inputFileUrl = [NSURLfileURLWithPath:self.videoPath];  //最終合成輸出路徑  NSString *outputFilePath =[documentsDirectorystringByAppendingPathComponent:@"final_video.mp4"];  NSURL *outputFileUrl = [NSURLfileURLWithPath:outputFilePath];  if([[NSFileManagerdefaultManager]fileExistsAtPath:outputFilePath])   [[NSFileManagerdefaultManager]removeItemAtPath:outputFilePatherror:nil];  CMTime nextClipStartTime =kCMTimeZero;  //創建可變的音頻視頻組合  AVMutableComposition* mixComposition =[AVMutableCompositioncomposition];  //視頻采集  AVURLAsset* videoAsset =[[AVURLAssetalloc]initWithURL:video_inputFileUrloptions:nil];  CMTimeRange video_timeRange =CMTimeRangeMake(kCMTimeZero,videoAsset.duration);  AVMutableCompositionTrack*a_compositionVideoTrack = [mixCompositionaddMutableTrackWithMediaType:AVMediaTypeVideopreferredTrackID:kCMPersistentTrackID_Invalid];  [a_compositionVideoTrackinsertTimeRange:video_timeRangeofTrack:[[videoAssettracksWithMediaType:AVMediaTypeVideo]objectAtIndex:0]atTime:nextClipStartTimeerror:nil];  //聲音采集  AVURLAsset* audioAsset =[[AVURLAssetalloc]initWithURL:audio_inputFileUrloptions:nil];  CMTimeRange audio_timeRange =CMTimeRangeMake(kCMTimeZero,videoAsset.duration);//聲音長度截取范圍==視頻長度  AVMutableCompositionTrack*b_compositionAudioTrack = [mixCompositionaddMutableTrackWithMediaType:AVMediaTypeAudiopreferredTrackID:kCMPersistentTrackID_Invalid];  [b_compositionAudioTrackinsertTimeRange:audio_timeRangeofTrack:[[audioAssettracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0]atTime:nextClipStartTimeerror:nil];  //創建一個輸出  AVAssetExportSession* _assetExport =[[AVAssetExportSessionalloc]initWithAsset:mixCompositionpresetName:AVAssetExportPresetMediumQuality];  _assetExport.outputFileType =AVFileTypeQuickTimeMovie;  _assetExport.outputURL =outputFileUrl;  _assetExport.shouldOptimizeForNetworkUse=YES;  self.theEndVideoURL=outputFileUrl;  [_assetExportexportAsynchronouslyWithCompletionHandler:  ^(void ) {   [MBProgressHUDhideHUDForView:self.viewanimated:YES];   //播放   NSURL*url = [NSURLfileURLWithPath:outputFilePath];   MPMoviePlayerViewController *theMovie =[[MPMoviePlayerViewControlleralloc]initWithContentURL:url];   [selfpresentMoviePlayerViewControllerAnimated:theMovie];   theMovie.moviePlayer.movieSourceType=MPMovieSourceTypeFile;   [theMovie.moviePlayerplay];  }  ];  NSLog(@"完成！輸出路徑==%@",outputFilePath); } //通過文件路徑建立和添加音頻素材 - (void)setUpAndAddAudioAtPath:(NSURL*)assetURLtoComposition:(AVMutableComposition*)composition start:(CMTime)startdura:(CMTime)duraoffset:(CMTime)offset{  AVURLAsset *songAsset =[AVURLAssetURLAssetWithURL:assetURLoptions:nil];  AVMutableCompositionTrack *track =[compositionaddMutableTrackWithMediaType:AVMediaTypeAudiopreferredTrackID:kCMPersistentTrackID_Invalid];  AVAssetTrack *sourceAudioTrack =[[songAssettracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0];  NSError *error =nil;  BOOL ok =NO;  CMTime startTime = start;  CMTime trackDuration = dura;  CMTimeRange tRange =CMTimeRangeMake(startTime,trackDuration);  //設置音量  //AVMutableAudioMixInputParameters（輸入參數可變的音頻混合）  //audioMixInputParametersWithTrack（音頻混音輸入參數與軌道）  AVMutableAudioMixInputParameters *trackMix =[AVMutableAudioMixInputParametersaudioMixInputParametersWithTrack:track];  [trackMixsetVolume:0.8fatTime:startTime];  //素材加入數組  [audioMixParamsaddObject:trackMix];  //Insert audio into track //offsetCMTimeMake(0, 44100)  ok = [trackinsertTimeRange:tRangeofTrack:sourceAudioTrackatTime:kCMTimeInvaliderror:&error]; }  #pragma mark - 保存路徑 -(NSString*)getLibarayPath {  NSFileManager *fileManager =[NSFileManagerdefaultManager];  NSArray* paths =NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);  NSString* path = [pathsobjectAtIndex:0];  NSString *movDirectory = [pathstringByAppendingPathComponent:@"tmpMovMix"];  [fileManagercreateDirectoryAtPath:movDirectorywithIntermediateDirectories:YESattributes:nilerror:nil];  return movDirectory; }