如何解决iOS中的视频定位问题

Question

我正在使用一个应用程序，用户从照片中选择视频并将其上传到服务器。 由于我的服务器是.Net服务器，因此视频会轮换。 我知道问题的原因可能与图像的情况相同（你可以参考我之前的答案https://stackoverflow.com/a/10601175/1030951 ），所以我用谷歌搜索并得到一个代码来修复视频方向 ，我从RayWenderlich.com获得代码并按以下方式修改。 现在我的输出视频工作正常，但视频是静音。 它播放但不播放音频。 如果我遗失了什么，请帮助我。

我传递信息字典-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info方法

- (void)fix:(NSDictionary*)pobjInfoDirectory withFileName:(NSString*)pstrOutputFileName
{
    firstAsset = [AVAsset assetWithURL:[pobjInfoDirectory objectForKey:UIImagePickerControllerMediaURL]];


    if(firstAsset !=nil)
    {
        //Create AVMutableComposition Object.This object will hold our multiple AVMutableCompositionTrack.
        AVMutableComposition* mixComposition = [[AVMutableComposition alloc] init];

        //VIDEO TRACK
        AVMutableCompositionTrack *firstTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
        [firstTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, firstAsset.duration) ofTrack:[[firstAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:kCMTimeZero error:nil];

        AVMutableVideoCompositionInstruction * MainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];

                MainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, firstAsset.duration);

        //FIXING ORIENTATION//
        AVMutableVideoCompositionLayerInstruction *FirstlayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:firstTrack];

        AVAssetTrack *FirstAssetTrack = [[firstAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];

        UIImageOrientation FirstAssetOrientation_  = UIImageOrientationUp;

        BOOL  isFirstAssetPortrait_  = NO;

        CGAffineTransform firstTransform = FirstAssetTrack.preferredTransform;

        if(firstTransform.a == 0 && firstTransform.b == 1.0 && firstTransform.c == -1.0 && firstTransform.d == 0)
        {
            FirstAssetOrientation_= UIImageOrientationRight; isFirstAssetPortrait_ = YES;
        }        
        if(firstTransform.a == 0 && firstTransform.b == -1.0 && firstTransform.c == 1.0 && firstTransform.d == 0)
        {
            FirstAssetOrientation_ =  UIImageOrientationLeft; isFirstAssetPortrait_ = YES;
        }
        if(firstTransform.a == 1.0 && firstTransform.b == 0 && firstTransform.c == 0 && firstTransform.d == 1.0)
        {
            FirstAssetOrientation_ =  UIImageOrientationUp;
        }
        if(firstTransform.a == -1.0 && firstTransform.b == 0 && firstTransform.c == 0 && firstTransform.d == -1.0)
        {
            FirstAssetOrientation_ = UIImageOrientationDown;
        }

        CGFloat FirstAssetScaleToFitRatio = 320.0/FirstAssetTrack.naturalSize.width;

        if(isFirstAssetPortrait_)
        {
            FirstAssetScaleToFitRatio = 320.0/FirstAssetTrack.naturalSize.height;
            CGAffineTransform FirstAssetScaleFactor = CGAffineTransformMakeScale(FirstAssetScaleToFitRatio,FirstAssetScaleToFitRatio);
            [FirstlayerInstruction setTransform:CGAffineTransformConcat(FirstAssetTrack.preferredTransform, FirstAssetScaleFactor) atTime:kCMTimeZero];
        }
        else
        {
            CGAffineTransform FirstAssetScaleFactor = CGAffineTransformMakeScale(FirstAssetScaleToFitRatio,FirstAssetScaleToFitRatio);
            [FirstlayerInstruction setTransform:CGAffineTransformConcat(CGAffineTransformConcat(FirstAssetTrack.preferredTransform, FirstAssetScaleFactor),CGAffineTransformMakeTranslation(0, 160)) atTime:kCMTimeZero];
        }
        [FirstlayerInstruction setOpacity:0.0 atTime:firstAsset.duration];

        MainInstruction.layerInstructions = [NSArray arrayWithObjects:FirstlayerInstruction,nil];;

        AVMutableVideoComposition *MainCompositionInst = [AVMutableVideoComposition videoComposition];
        MainCompositionInst.instructions = [NSArray arrayWithObject:MainInstruction];
        MainCompositionInst.frameDuration = CMTimeMake(1, 30);
        MainCompositionInst.renderSize = CGSizeMake(320.0, 480.0);

        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString *myPathDocs =  [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"mergeVideo-%d.mov",arc4random() % 1000]];

        NSURL *url = [NSURL fileURLWithPath:myPathDocs];

        AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];

        exporter.outputURL=url;
        exporter.outputFileType = AVFileTypeQuickTimeMovie;
        exporter.videoComposition = MainCompositionInst;
        exporter.shouldOptimizeForNetworkUse = YES;
        [exporter exportAsynchronouslyWithCompletionHandler:^
         {
             dispatch_async(dispatch_get_main_queue(), ^{
                 [self exportDidFinish:exporter];
             });
         }];
    }
}

- (void)exportDidFinish:(AVAssetExportSession*)session
{
    if(session.status == AVAssetExportSessionStatusCompleted)
    {
        NSURL *outputURL = session.outputURL;
        ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];

        if ([library videoAtPathIsCompatibleWithSavedPhotosAlbum:outputURL])
        {
            if ([self.delegate respondsToSelector:@selector(videoExported)])
                [self.delegate videoExported];    
        }
    }       
    firstAsset = nil;
}

Answer 1

在//VIDEO TRACK部分之后添加

        //AUDIO TRACK
        AVMutableCompositionTrack *firstAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
        [firstAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, firstAsset.duration) ofTrack:[[firstAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:kCMTimeZero error:nil];

Answer 2

AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:@"your video url here..." options:nil];

在AVMutableCompositionTrack之后添加。

set setPreferredTransform:在此处设置要以相同方向导出的源视频。

 // Grab the source track from AVURLAsset for example.
AVAssetTrack *assetVideoTrack = [videoAsset tracksWithMediaType:AVMediaTypeVideo].lastObject;

// Grab the composition video track from AVMutableComposition you already made.
AVMutableCompositionTrack *compositionVideoTrack = [mixComposition tracksWithMediaType:AVMediaTypeVideo].lastObject;

// Apply the original transform.
if (assetVideoTrack && compositionVideoTrack) {
        [compositionVideoTrack setPreferredTransform:assetVideoTrack.preferredTransform];
    }