合併音頻和視頻

Question

我有一個應用程序，我需要將音頻文件合併到視頻文件中。

有時我的音頻文件大於視頻文件的持續時間。我曾使用AVFoundation的MixComposition，兩者都被合併。但問題是，如果視頻文件的持續時間較短，那麼當視頻結束時，聲音仍會繼續播放並完成整個持續時間。它應該是如果視頻完成音頻必須停止。

任何人都可以提供任何解決方案。

Answer 1

使用下面的代碼停止你的音頻，同時也創造最後5秒鐘

淡出音頻

- (void)getFadeAudioFile { 

    if (![appDelegate.musicFilePath isEqualToString:@"Not set"]) { 
     NSURL *url = [[[NSURL alloc]initWithString:appDelegate.musicFilePath]autorelease]; 

     AVURLAsset* audioAsset = [[[AVURLAsset alloc]initWithURL:url options:nil]autorelease]; 

     NSString *filePath = [self applicationDocumentsDirectory]; 
     NSString *outputFilePath = nil; 
     outputFilePath = [filePath stringByAppendingPathComponent:@"/mySong.m4a"]; 
     NSURL *outputFileUrl = [[[NSURL alloc]initFileURLWithPath:outputFilePath]autorelease]; 

     NSError *theError = nil; 

     if ([[NSFileManager defaultManager] fileExistsAtPath:outputFilePath]) 
      [[NSFileManager defaultManager] removeItemAtPath:outputFilePath error:&theError]; 

     [self exportAsset:audioAsset toFilePath:outputFileUrl]; 

    } 
} 

- (BOOL)exportAsset:(AVAsset *)avAsset toFilePath:(NSURL *)filePath { 

    // get the first audio track 
    NSArray *tracks = [avAsset tracksWithMediaType:AVMediaTypeAudio]; 
    if ([tracks count] == 0) return NO; 

    AVAssetTrack *track = [tracks objectAtIndex:0]; 

    // create the export session 
    // no need to retain here since the session will be retained by the 
    // completion handler since it is referenced there 

    AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:avAsset presetName:AVAssetExportPresetAppleM4A]; 
    if (nil == exportSession) return NO; 

    NSLog(@"arrOfImagesForVideo.coun:%d",arrImageDataDict.count); 

    int imgCount = arrImageDataDict.count+1; 
    int delay = appDelegate.delaySecond; 

    int duration = imgCount*delay; 

    CMTime stopTime = CMTimeMake(duration, 1); 

    // create trim time range - 20 seconds starting from 30 seconds into the asset 
    // NSInteger totalTime = CMTimeGetSeconds(avAsset.duration); 

    CMTime startTime = CMTimeMake(0, 1); 
    //CMTime stopTime = CMTimeMake(totalTime, 1);//0,30 
    CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime); 

    // create fade in time range - 10 seconds starting at the beginning of trimmed asset 
    NSInteger fadeTime = duration-5; 

    NSLog(@"fade time:%d",fadeTime); 
    NSLog(@"fade duration:%d",duration); 

    CMTime startFadeInTime = CMTimeMake(fadeTime, 1); 
    CMTime endFadeInTime = CMTimeMake(duration, 1); 
    CMTimeRange fadeInTimeRange = CMTimeRangeFromTimeToTime(startFadeInTime, endFadeInTime); 

    // setup audio mix 
    AVMutableAudioMix *exportAudioMix = [AVMutableAudioMix audioMix]; 
    AVMutableAudioMixInputParameters *exportAudioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:track]; 

    [exportAudioMixInputParameters setVolumeRampFromStartVolume:1.0 toEndVolume:0.0 timeRange:fadeInTimeRange]; 
    exportAudioMix.inputParameters = [NSArray arrayWithObject:exportAudioMixInputParameters]; 

    // configure export session output with all our parameters 
    exportSession.outputURL = filePath; // output path 
    exportSession.outputFileType = AVFileTypeAppleM4A;   // output file type 
    exportSession.timeRange = exportTimeRange;     // trim time range 
    exportSession.audioMix = exportAudioMix;     // fade in audio mix 

    [exportSession exportAsynchronouslyWithCompletionHandler: 
      ^(void) { 
       //[self saveVideoToAlbum:outputFilePath]; 
      } 
      ]; 

    return YES; 
} 

它將被保存在你的文件路徑，文件目錄，並使用它像

NSString *filePath = [self applicationDocumentsDirectory]; 
NSString *outputFilePath1 = [filePath tringByAppendingPathComponent:@"/mySong.m4a"]; 

NSURL *audio_inputFileUrl = [[NSURL alloc]initFileURLWithPath:outputFilePath1]; 
int imgCount = imageArray.count; 
int delay = appDelegate.delaySecond; 

NSLog(@"audio merged"); 
int duration = imgCount*delay; 

CMTime seekingCM = CMTimeMake(duration, 1); 

AVURLAsset* audioAsset = [[AVURLAsset alloc]initWithURL:audio_inputFileUrl options:nil]; 
CMTimeRange audio_timeRange = CMTimeRangeMake(kCMTimeZero, seekingCM); 
AVMutableCompositionTrack *b_compositionAudioTrack = [mixComposition MutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid]; 
[b_compositionAudioTrack insertTimeRange:audio_timeRange ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:nextClipStartTime error:nil]; 
//[audioAsset autorelease]; 
newAudioTrack = [audioAsset tracksWithMediaType:AVMediaTypeAudio][0];