IOS視訊新增背景音樂同時保留原音

//抽取原視訊的音訊與需要的音樂混合  
-(void)addmusic:(id)sender  
{  
   [MBProgressHUDshowHUDAddedTo:self.viewanimated:YES];  

   AVMutableComposition *composition =[AVMutableCompositioncomposition];  
   audioMixParams =[[NSMutableArrayalloc]initWithObjects:nil];  

   //錄製的視訊  
   NSURL *video_inputFileUrl =[NSURLfileURLWithPath:self
 
.videoPath];  
   AVURLAsset *songAsset =[AVURLAssetURLAssetWithURL:video_inputFileUrloptions:nil];  
   CMTime startTime =CMTimeMakeWithSeconds(0,songAsset.duration.timescale);  
   CMTime trackDuration =songAsset.duration;  

   //獲取視訊中的音訊素材  
   [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];  
   //獲取設定完的本地音樂素材  
   [selfsetUpAndAddAudioAtPath:assetURL2toComposition:compositionstart:startTimedura:trackDurationoffset:CMTimeMake(0
 
,44100)];  

   //建立一個可變的音訊混合  
   AVMutableAudioMix *audioMix =[AVMutableAudioMixaudioMix];  
   audioMix.inputParameters =[NSArrayarrayWithArray:audioMixParams];//從數組裡取出處理後的音訊軌道引數  

   //建立一個輸出  
   AVAssetExportSession *exporter =[[AVAssetExportSessionalloc]  
                                initWithAsset:composition  
                                presetName:AVAssetExportPresetAppleM4A];  
   exporter.audioMix = audioMix;  
   exporter.outputFileType[email protected]"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(@"是否在主執行緒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，資訊: %@", exportError);  
             [MBProgressHUDhideHUDForView:self.viewanimated:YES];  
             break;  
           }  
          caseAVAssetExportSessionStatusCompleted:{  
             NSLog(@"是否在主執行緒2%d",[NSThreadisMainThread]);  
              NSLog(@"成功");  
             //最終混合  
              [selftheVideoWithMixMusic];  
             break;  
           }  
       }  
    }];  

}  

//最終音訊和視訊混合  
-(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(@"無法刪除檔案，錯誤資訊：%@",[error localizedDescription]);  
    }  

   //聲音來源路徑（最終混合的音訊）  
   NSURL   *audio_inputFileUrl =self.mixURL;  

   //視訊來源路徑  
   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;  

   //建立可變的音訊視訊組合  
   AVMutableComposition* mixComposition =[AVMutableCompositioncomposition];  

   //視訊採集  
   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];  

   //聲音採集  
   AVURLAsset* audioAsset =[[AVURLAssetalloc]initWithURL:audio_inputFileUrloptions:nil];  
   CMTimeRange audio_timeRange =CMTimeRangeMake(kCMTimeZero,videoAsset.duration);//聲音長度擷取範圍==視訊長度  
   AVMutableCompositionTrack*b_compositionAudioTrack = [mixCompositionaddMutableTrackWithMediaType:AVMediaTypeAudiopreferredTrackID:kCMPersistentTrackID_Invalid];  
   [b_compositionAudioTrackinsertTimeRange:audio_timeRangeofTrack:[[audioAssettracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0]atTime:nextClipStartTimeerror:nil];  

   //建立一個輸出  
   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);  
}  

//通過檔案路徑建立和新增音訊素材  
- (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);  

   //設定音量  
   //AVMutableAudioMixInputParameters（輸入引數可變的音訊混合）  
   //audioMixInputParametersWithTrack（音訊混音輸入引數與軌道）  
   AVMutableAudioMixInputParameters *trackMix =[AVMutableAudioMixInputParametersaudioMixInputParametersWithTrack:track];  
    [trackMixsetVolume:0.8fatTime:startTime];  

   //素材加入陣列  
   [audioMixParamsaddObject:trackMix];  

   //Insert audio into track  //offsetCMTimeMake(0, 44100)  
    ok = [trackinsertTimeRange:tRangeofTrack:sourceAudioTrackatTime:kCMTimeInvaliderror:&error];  
}  

 #pragma mark - 儲存路徑  
-(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;  

}