我目前正在使用合并所需数量的视频的iOS应用程序。用户点击按钮合并视频后，将加入视频，然后使用Avplayer播放为：
CMTime nextClipStartTime = kCMTimeZero;
NSInteger i;
CMTime transitionDuration = CMTimeMake(1, 1); // Default transition duration is one second.
// Add two video tracks and two audio tracks.
AVMutableCompositionTrack *compositionVideoTracks[2];
AVMutableCompositionTrack *compositionAudioTracks[2];
compositionVideoTracks[0] = [self.mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
compositionVideoTracks[1] = [self.mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
compositionAudioTracks[0] = [self.mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
compositionAudioTracks[1] = [self.mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
CMTimeRange *passThroughTimeRanges = alloca(sizeof(CMTimeRange) * [self.selectedAssets count]);
CMTimeRange *transitionTimeRanges = alloca(sizeof(CMTimeRange) * [self.selectedAssets count]);
// Place clips into alternating video & audio tracks in composition, overlapped by transitionDuration.
for (i = 0; i < [self.selectedAssets count]; i++ )
{
NSInteger alternatingIndex = i % 2; // alternating targets: 0, 1, 0, 1, ...
AVURLAsset *asset = [self.selectedAssets objectAtIndex:i];
NSLog(@"number of tracks %d",asset.tracks.count);
CMTimeRange assetTimeRange;
assetTimeRange.start = kCMTimeZero;
assetTimeRange.duration = asset.duration;
NSValue *clipTimeRange = [NSValue valueWithCMTimeRange:assetTimeRange];
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];
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 < [self.selectedAssets 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 < [self.selectedAssets 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]];
passThroughInstruction.layerInstructions = [NSArray arrayWithObject:passThroughLayer];
[instructions addObject:passThroughInstruction];
AVMutableVideoCompositionLayerInstruction *fromLayer;
AVMutableVideoCompositionLayerInstruction *toLayer;
if (i+1 < [self.selectedAssets count])
{
// Add transition from clip i to clip i+1.
AVMutableVideoCompositionInstruction *transitionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
transitionInstruction.timeRange = transitionTimeRanges[i];
fromLayer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTracks[alternatingIndex]];
toLayer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTracks[1-alternatingIndex]];
// Fade out the fromLayer by setting a ramp from 1.0 to 0.0.
[fromLayer setOpacityRampFromStartOpacity:1.0 toEndOpacity:0.0 timeRange:transitionTimeRanges[i]];
transitionInstruction.layerInstructions = [NSArray arrayWithObjects:fromLayer, toLayer, nil];
[instructions addObject:transitionInstruction];
}
AVURLAsset *sourceAsset = [AVURLAsset URLAssetWithURL:[self.selectedItemsURL objectAtIndex:i] options:[NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:AVURLAssetPreferPreciseDurationAndTimingKey]];
AVAssetTrack *sourceVideoTrack = [[sourceAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
CGSize temp = CGSizeApplyAffineTransform(sourceVideoTrack.naturalSize, sourceVideoTrack.preferredTransform);
CGSize size = CGSizeMake(fabsf(temp.width), fabsf(temp.height));
CGAffineTransform transform = sourceVideoTrack.preferredTransform;
self.videoComposition.renderSize = sourceVideoTrack.naturalSize;
if (size.width > size.height) {
[fromLayer setTransform:transform atTime:sourceAsset.duration];
} else {
float s = size.width/size.height;
CGAffineTransform new = CGAffineTransformConcat(transform, CGAffineTransformMakeScale(s,s));
float x = (size.height - size.width*s)/2;
CGAffineTransform newer = CGAffineTransformConcat(new, CGAffineTransformMakeTranslation(x, 0));
[fromLayer setTransform:newer atTime:sourceAsset.duration];
}
}
self.videoComposition.instructions = instructions;
self.videoComposition.frameDuration = CMTimeMake(1, 30);
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];
self.exporter = [[AVAssetExportSession alloc] initWithAsset:self.mixComposition presetName:AVAssetExportPresetMediumQuality];
self.exporter.outputURL=url;
self.exporter.outputFileType = AVFileTypeQuickTimeMovie;
self.exporter.videoComposition = self.videoComposition;
self.exporter.shouldOptimizeForNetworkUse = YES;
self.playerItem = [AVPlayerItem playerItemWithAsset:self.mixComposition];
self.playerItem.videoComposition = self.videoComposition;
AVPlayer *player = [AVPlayer playerWithPlayerItem:self.playerItem];
AVPlayerLayer *playerLayer = [AVPlayerLayer playerLayerWithPlayer:player];
[playerLayer setFrame:CGRectMake(0, 0, self.imageView.frame.size.width, self.imageView.frame.size.height)];
[[[self imageView] layer] addSublayer:playerLayer];
playerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[player play];
[[NSNotificationCenter defaultCenter]
addObserver:self selector:@selector(checkPlayEnded) name:AVPlayerItemDidPlayToEndTimeNotification object:self.playerItem];
我目前面临以下问题：
如果一个视频在肖像中，而另一个视频在景观中，那么我将如何在景观中旋转肖像视频，因为我的观点是景观方向，而肖像视频保留了它的原始视频？（我正在加载存储在相机卷中的视频，而不是在我的应用中记录它们）
忽略上述问题，如果我合并了任何数量的视频，它们都可以正常工作。一旦我将该新视频保存在库中，然后再次将其加载到我的应用中，并尝试与其他一些新视频一起加入该视频，尽管两个视频在应用程序中单独播放，但该分辨率都会受到打扰。我该如何解决？
（我试图遵循WWDC 2010视频编辑教程，因此从那里提取此代码。）
您可以在为avmutableVideOpospositionstructions创建对象时在上述代码中检查视频运行时间的方向。
要附加到代码以解决问题的代码是....
AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, [mutableComposition duration]);
AVAssetTrack *videoTrack = [[mutableComposition tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVMutableVideoCompositionLayerInstruction * layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
UIImageOrientation videoAssetOrientation_ = UIImageOrientationUp;
BOOL isVideoAssetPortrait_ = NO;
CGAffineTransform videoTransform = assetVideoTrack.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;
}
CGFloat FirstAssetScaleToFitRatio = 320.0 / assetVideoTrack.naturalSize.width;
if(isVideoAssetPortrait_)
{
videoSize=CGSizeMake(350,400);
FirstAssetScaleToFitRatio = 320.0/assetVideoTrack.naturalSize.height;
CGAffineTransform FirstAssetScaleFactor = CGAffineTransformMakeScale(FirstAssetScaleToFitRatio,FirstAssetScaleToFitRatio);
[layerInstruction setTransform:CGAffineTransformConcat(assetVideoTrack.preferredTransform, FirstAssetScaleFactor) atTime:kCMTimeZero];
}
else
{
videoSize=CGSizeMake(assetVideoTrack.naturalSize.width,assetVideoTrack.naturalSize.height);
}
上面的代码将使景观视频保持在景观中，并防止视频从肖像转换为景观。
我希望这会有所帮助。首先转换为适当的方向然后应用编辑。如果您附加此代码，则您的一个步骤将减少，并且可以在一个代码中完成这两个方案（即编辑＆amp; entrientation），也可以在更快的方式。