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我正在将叠加层添加到视频中，并在 Facebook 和 whatsaap 上分享。但是视频的质量特别是在whatsapp上变得很差，而其他没有覆盖的视频质量最好。用 overlay 编辑覆盖视频的代码：

AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:outputFileURL options:nil];
AVMutableComposition* mixComposition = [AVMutableComposition composition];

AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo  preferredTrackID:kCMPersistentTrackID_Invalid];
AVMutableCompositionTrack *audioComposition = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
AVAssetTrack *clipVideoTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVAssetTrack *sourceAudioTrack = [[videoAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];

[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
                               ofTrack:clipVideoTrack
                                atTime:kCMTimeZero error:nil];
[audioComposition insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:sourceAudioTrack atTime:kCMTimeZero error:nil]; //[asset duration]

[compositionVideoTrack setPreferredTransform:[[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] preferredTransform]];

AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, [mixComposition duration]);
AVAssetTrack *videoTrack = [[mixComposition tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVMutableVideoCompositionLayerInstruction* layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];

//*****************//
UIImageOrientation videoAssetOrientation_;// = UIImageOrientationUp;
BOOL isVideoAssetPortrait_  = NO;
CGAffineTransform videoTransform = clipVideoTrack.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;
    isVideoAssetPortrait_ = NO;
}
if (videoTransform.a == -1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == -1.0) {
   videoAssetOrientation_ = UIImageOrientationDown;
    isVideoAssetPortrait_ = NO;
}
[layerInstruction setTransform:clipVideoTrack.preferredTransform atTime:kCMTimeZero];
[layerInstruction setOpacity:0.0 atTime:videoAsset.duration];
//*****************//
CGSize naturalSize;
if(isVideoAssetPortrait_){
    naturalSize = CGSizeMake(clipVideoTrack.naturalSize.height, clipVideoTrack.naturalSize.width);
} else {
    naturalSize = clipVideoTrack.naturalSize;
}


UIImage *myImage = [UIImage imageNamed:@"overlay.png"];
CALayer *aLayer = [CALayer layer];
if (naturalSize.width > 359) {
    aLayer.frame = CGRectMake((naturalSize.width-340)/2, 0, 340, 90);

}
 else if (naturalSize.width > 200) {
     aLayer.frame = CGRectMake(10, 0, naturalSize.width-20, 65);
}
else{
     aLayer.frame = CGRectMake(15, 0, naturalSize.width-30, 60);

}
aLayer.contents = (id)myImage.CGImage;
//Needed for proper display. We are using the app icon (57x57). If you use 0,0 you will not see it
// aLayer.opacity = 1.0; //Feel free to alter the alpha here

aLayer.backgroundColor = [UIColor clearColor].CGColor;
[aLayer setMasksToBounds:YES];
// CGSize videoSize = [videoAsset naturalSize];
CALayer *parentLayer = [CALayer layer];
CALayer *videoLayer = [CALayer layer];


//NSURL *url = [NSURL fileURLWithPath:[urlsOfVideos objectAtIndex:self.pageControl.currentPage]];

 NSLog(@"videoSize ++++: %@", NSStringFromCGSize(naturalSize));
AVMutableVideoComposition* videoComp = [AVMutableVideoComposition videoComposition] ;

float renderWidth, renderHeight;
renderWidth = naturalSize.width;
renderHeight = naturalSize.height;
videoComp.renderSize = CGSizeMake(renderWidth, renderHeight);
videoComp.instructions = [NSArray arrayWithObject:instruction];
videoComp.frameDuration = CMTimeMake(1, 30);


videoLayer.frame = CGRectMake(0, 0, naturalSize.width, naturalSize.height);
parentLayer.frame = CGRectMake(0, 0, naturalSize.width, naturalSize.height);
[parentLayer addSublayer:videoLayer];
[parentLayer addSublayer:aLayer];

videoComp.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];

/// instruction

instruction.layerInstructions = [NSArray arrayWithObject:layerInstruction];
videoComp.instructions = [NSArray arrayWithObject: instruction];

assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];

assetExport.outputURL = exportUrl;
assetExport.outputFileType = AVFileTypeQuickTimeMovie;
assetExport.shouldOptimizeForNetworkUse = YES;
assetExport.videoComposition = videoComp;

//[strRecordedFilename setString: exportPath];

[assetExport exportAsynchronouslyWithCompletionHandler:
 ^(void ) {
     switch (assetExport.status) {
         case AVAssetExportSessionStatusFailed:{
             NSLog(@"Fail");
             NSLog(@"asset export fail error : %@", assetExport.error);

             dispatch_async(dispatch_get_main_queue(), ^
                            {

                            });

             break;
         }
         case AVAssetExportSessionStatusCompleted:{
             NSLog(@"Success");

                              dispatch_async(dispatch_get_main_queue(), ^
                            {

                            });


             break;
         }

         default:
             break;
     }

 }       
 ];   
}

我究竟做错了什么？任何想法？

4

1 回答 1

1

使用以下代码在视频上添加叠加层：

CALayer *overlayLayer = [CALayer layer];
UIImage *overlayImage = [UIImage imageNamed:@"overlay.png"];
[overlayLayer setContents:(id)[overlayImage CGImage]];
overlayLayer.frame = CGRectMake(0, 0, size.width, size.height);
[overlayLayer setMasksToBounds:YES];

//Set Up the Parent Layer
CALayer *parentLayer = [CALayer layer];
CALayer *videoLayer = [CALayer layer];
parentLayer.frame = CGRectMake(0, 0, size.width, size.height);
videoLayer.frame = CGRectMake(0, 0, size.width, size.height);
[parentLayer addSublayer:videoLayer];
[parentLayer addSublayer:overlayLayer];

看看下面的链接包含很好的教程：

http://www.raywenderlich.com/30200/avfoundation-tutorial-adding-overlays-and-animations-to-videos

于 2014-01-23T06:34:19.710 回答