AVMutableVideoComposition 以纵向模式捕获的旋转视频 [英] AVMutableVideoComposition rotated video captured in portrait mode

问题描述

我使用以下代码在视频上添加图像叠加，然后将新生成的视频导出到文档目录.但奇怪的是，视频旋转了 90 度.

I have used below code to add image overlay over video and then export the new generated video to document directory. But strangely,video gets rotated by 90 degrees.

- (void)buildTransitionComposition:(AVMutableComposition *)composition andVideoComposition:(AVMutableVideoComposition *)videoComposition
{
    CMTime nextClipStartTime = kCMTimeZero;
    NSInteger i;

    // Make transitionDuration no greater than half the shortest clip duration.
    CMTime transitionDuration = self.transitionDuration;
    for (i = 0; i < [_clips count]; i++ ) {
        NSValue *clipTimeRange = [_clipTimeRanges objectAtIndex:i];
        if (clipTimeRange) {
            CMTime halfClipDuration = [clipTimeRange CMTimeRangeValue].duration;
            halfClipDuration.timescale *= 2; // You can halve a rational by doubling its denominator.
            transitionDuration = CMTimeMinimum(transitionDuration, halfClipDuration);
        }
    }

    // Add two video tracks and two audio tracks.
    AVMutableCompositionTrack *compositionVideoTracks[2];
    AVMutableCompositionTrack *compositionAudioTracks[2];
    compositionVideoTracks[0] = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    compositionVideoTracks[1] = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    compositionAudioTracks[0] = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    compositionAudioTracks[1] = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

    CMTimeRange *passThroughTimeRanges = alloca(sizeof(CMTimeRange) * [_clips count]);
    CMTimeRange *transitionTimeRanges = alloca(sizeof(CMTimeRange) * [_clips count]);

    // Place clips into alternating video & audio tracks in composition, overlapped by transitionDuration.
    for (i = 0; i < [_clips count]; i++ ) {
        NSInteger alternatingIndex = i % 2; // alternating targets: 0, 1, 0, 1, ...
        AVURLAsset *asset = [_clips objectAtIndex:i];
        NSValue *clipTimeRange = [_clipTimeRanges objectAtIndex:i];
        CMTimeRange timeRangeInAsset;
        if (clipTimeRange)
            timeRangeInAsset = [clipTimeRange CMTimeRangeValue];
        else
            timeRangeInAsset = CMTimeRangeMake(kCMTimeZero, [asset duration]);

        AVAssetTrack *clipVideoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
        [compositionVideoTracks[alternatingIndex] insertTimeRange:timeRangeInAsset ofTrack:clipVideoTrack atTime:nextClipStartTime error:nil];

        /*
        CGAffineTransform t = clipVideoTrack.preferredTransform;
        NSLog(@"Transform1 : %@",t);
        */
        AVAssetTrack *clipAudioTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
        [compositionAudioTracks[alternatingIndex] insertTimeRange:timeRangeInAsset ofTrack:clipAudioTrack atTime:nextClipStartTime error:nil];

        // Remember the time range in which this clip should pass through.
        // Every clip after the first begins with a transition.
        // Every clip before the last ends with a transition.
        // Exclude those transitions from the pass through time ranges.
        passThroughTimeRanges[i] = CMTimeRangeMake(nextClipStartTime, timeRangeInAsset.duration);
        if (i > 0) {
            passThroughTimeRanges[i].start = CMTimeAdd(passThroughTimeRanges[i].start, transitionDuration);
            passThroughTimeRanges[i].duration = CMTimeSubtract(passThroughTimeRanges[i].duration, transitionDuration);
        }
        if (i+1 < [_clips count]) {
            passThroughTimeRanges[i].duration = CMTimeSubtract(passThroughTimeRanges[i].duration, transitionDuration);
        }

        // The end of this clip will overlap the start of the next by transitionDuration.
        // (Note: this arithmetic falls apart if timeRangeInAsset.duration < 2 * transitionDuration.)
        nextClipStartTime = CMTimeAdd(nextClipStartTime, timeRangeInAsset.duration);
        nextClipStartTime = CMTimeSubtract(nextClipStartTime, transitionDuration);

        // Remember the time range for the transition to the next item.
        transitionTimeRanges[i] = CMTimeRangeMake(nextClipStartTime, transitionDuration);
    }

    // Set up the video composition if we are to perform crossfade or push transitions between clips.
    NSMutableArray *instructions = [NSMutableArray array];

    // Cycle between "pass through A", "transition from A to B", "pass through B", "transition from B to A".
    for (i = 0; i < [_clips count]; i++ ) {
        NSInteger alternatingIndex = i % 2; // alternating targets

        // Pass through clip i.
        AVMutableVideoCompositionInstruction *passThroughInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
        passThroughInstruction.timeRange = passThroughTimeRanges[i];
        AVMutableVideoCompositionLayerInstruction *passThroughLayer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTracks[alternatingIndex]];
        /*
        CGAffineTransform rotationTransform = CGAffineTransformMakeRotation(M_PI_2);
        CGAffineTransform rotateTranslate = CGAffineTransformTranslate(rotationTransform,320,0);
        [passThroughLayer setTransform:rotateTranslate atTime:kCMTimeZero];
         */
        passThroughInstruction.layerInstructions = [NSArray arrayWithObject:passThroughLayer];
        [instructions addObject:passThroughInstruction];

        if (i+1 < [_clips count]) {
            // Add transition from clip i to clip i+1.

            AVMutableVideoCompositionInstruction *transitionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
            transitionInstruction.timeRange = transitionTimeRanges[i];
            AVMutableVideoCompositionLayerInstruction *fromLayer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTracks[alternatingIndex]];
            AVMutableVideoCompositionLayerInstruction *toLayer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTracks[1-alternatingIndex]];

            if (self.transitionType == SimpleEditorTransitionTypeCrossFade) {
                // Fade out the fromLayer by setting a ramp from 1.0 to 0.0.
                [fromLayer setOpacityRampFromStartOpacity:1.0 toEndOpacity:0.0 timeRange:transitionTimeRanges[i]];
            }
            else if (self.transitionType == SimpleEditorTransitionTypePush) {
                // Set a transform ramp on fromLayer from identity to all the way left of the screen.
                [fromLayer setTransformRampFromStartTransform:CGAffineTransformIdentity toEndTransform:CGAffineTransformMakeTranslation(-composition.naturalSize.width, 0.0) timeRange:transitionTimeRanges[i]];
                // Set a transform ramp on toLayer from all the way right of the screen to identity.
                [toLayer setTransformRampFromStartTransform:CGAffineTransformMakeTranslation(+composition.naturalSize.width, 0.0) toEndTransform:CGAffineTransformIdentity timeRange:transitionTimeRanges[i]];
            }

            transitionInstruction.layerInstructions = [NSArray arrayWithObjects:fromLayer, toLayer, nil];
            [instructions addObject:transitionInstruction];
        }
    }

    videoComposition.instructions = instructions;


}

请帮忙，因为我无法以正确的模式导出纵向视频.感谢任何帮助.谢谢.

Please help,as I am not able to export portrait video in proper mode.Any help appreciated. Thank you.

推荐答案

默认情况下，当您使用 AVAssetExportSession 导出视频时，视频将从其原始方向旋转.你必须应用它的变换来设置它的精确方向.你请尝试下面的代码来做同样的事情.

By default, when you export video using AVAssetExportSession then video will be rotated from its original orientation. You have to apply its transform to set it exact orientation.You please try below code to do the same.

- (AVMutableVideoCompositionLayerInstruction *)layerInstructionAfterFixingOrientationForAsset:(AVAsset *)inAsset 
                                                                                     forTrack:(AVMutableCompositionTrack *)inTrack
                                                                                       atTime:(CMTime)inTime
{
    //FIXING ORIENTATION//
    AVMutableVideoCompositionLayerInstruction *videolayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:inTrack];
    AVAssetTrack *videoAssetTrack = [[inAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
    UIImageOrientation videoAssetOrientation_  = UIImageOrientationUp;
    BOOL  isVideoAssetPortrait_  = NO;
    CGAffineTransform videoTransform = videoAssetTrack.preferredTransform;

    if(videoTransform.a == 0 && videoTransform.b == 1.0 && videoTransform.c == -1.0 && videoTransform.d == 0)  {videoAssetOrientation_= UIImageOrientationRight; isVideoAssetPortrait_ = YES;}
    if(videoTransform.a == 0 && videoTransform.b == -1.0 && videoTransform.c == 1.0 && videoTransform.d == 0)  {videoAssetOrientation_ =  UIImageOrientationLeft; isVideoAssetPortrait_ = YES;}
    if(videoTransform.a == 1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == 1.0)   {videoAssetOrientation_ =  UIImageOrientationUp;}
    if(videoTransform.a == -1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == -1.0) {videoAssetOrientation_ = UIImageOrientationDown;}

    CGFloat FirstAssetScaleToFitRatio = 320.0 / videoAssetTrack.naturalSize.width;

    if(isVideoAssetPortrait_) {
        FirstAssetScaleToFitRatio = 320.0/videoAssetTrack.naturalSize.height;
        CGAffineTransform FirstAssetScaleFactor = CGAffineTransformMakeScale(FirstAssetScaleToFitRatio,FirstAssetScaleToFitRatio);
        [videolayerInstruction setTransform:CGAffineTransformConcat(videoAssetTrack.preferredTransform, FirstAssetScaleFactor) atTime:kCMTimeZero];
    }else{
        CGAffineTransform FirstAssetScaleFactor = CGAffineTransformMakeScale(FirstAssetScaleToFitRatio,FirstAssetScaleToFitRatio);
        [videolayerInstruction setTransform:CGAffineTransformConcat(CGAffineTransformConcat(videoAssetTrack.preferredTransform, FirstAssetScaleFactor),CGAffineTransformMakeTranslation(0, 160)) atTime:kCMTimeZero];
    }
    [videolayerInstruction setOpacity:0.0 atTime:inTime];
    return videolayerInstruction;
}

希望对你有所帮助.

AVAssetTrack *assetTrack = [[inAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];

AVMutableCompositionTrack *mutableTrack = [mergeComposition mutableTrackCompatibleWithTrack:assetTrack];

AVMutableVideoCompositionLayerInstruction *assetInstruction = [self layerInstructionAfterFixingOrientationForAsset:inAsset forTrack:myLocalVideoTrack atTime:videoTotalDuration];

以上是调用上述方法的代码，其中 inAsset 是您的视频资产，videoTotalDuration 是您在 CMTime.mergeComposition 中的视频总持续时间AVMutableComposition 类的对象.

Above is the code to call mentioned method where inAsset is your video asset and videoTotalDuration is your video total duration in CMTime.mergeComposition is object of AVMutableComposition class.

希望这会有所帮助.

这不是任何回调方法或事件，您必须使用上面提到的所需参数按预期调用它.

This is not any callback method or event, you have to call it expectedly with required parameters as mentioned above.

这篇关于AVMutableVideoComposition 以纵向模式捕获的旋转视频的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！