如何在iOS中修复视频方向问题

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，所以视频会被旋转。我知道问题的原因可能与图像的情况相同（您可以参考我之前的答案https://dev59.com/TWkv5IYBdhLWcg3wbgUx#10601175），所以我进行了谷歌搜索，并获得了一段代码来解决视频方向问题。我从RayWenderlich.com获得了一段代码，并按以下方式进行了修改。现在我的输出视频效果很好，但没有声音。请帮助我，如果我漏掉了什么。

我传递了-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info方法的 Info 字典。

- (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;
}

- HarshIT

---

你确定不是你的iPhone被静音了吗？ - Rui Peres

检查这个可能会对你有所帮助：http://stackoverflow.com/questions/2814626/programatically-access-orientation-of-an-iphone-video - Nitin Gohel

@NitinGohel，谢谢，但它只检测视频的方向，我已经在else if梯度中完成了相同的操作。我的问题是声音不播放，只有音频播放。 - HarshIT

@HarshIT，我想合并竖屏和横屏视频，但我无法弄清楚。请问我能加入这个群吗？ - Vatsal Shukla

@Vats，抱歉由于一些繁忙的日程，我没有及时回复你。要合并具有如此不同方向的视频，您可能需要调整视频帧的大小，我相信。 - HarshIT

Answer 1

请将以下内容添加到//VIDEO TRACK之后

        //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];

- Or Arbel

---

它对视频也适用吗？我的意思是，在应用转换后，合并的视频方向出现了问题。任何帮助都将不胜感激。 - Abdul Yasin

@AbdulYasin，你找到合并后方向问题的解决方案了吗？如果是的话，能给我一些建议吗？ - Nilesh

Answer 2

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

在 AVMutableCompositionTrack 后添加内容。

使用 setPreferredTransform: 设置你想要以相同方向导出的源视频。请在此处设置。

 // 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];
    }

- kuldip bhalodiya