0
我想要的：在AVVideoCompositionTrack时间0:00插入多个不透明度为ALL的视频图层。使用AVFoundation没有CALayer合成2个半透明不透明的视频变成附加视频？
我仔细阅读了官方AVFoundation文档以及许多WWDC关于此主题的讨论。但我不明白为什么结果不遵循API声明。
我可以在播放过程中用2 AVPlayerLayer实现重叠结果。这也意味着我可以使用AVVideoCompositionCoreAnimationTool在导出过程中实现类似的功能。 但我倾向于将CALayer留给字幕/图像叠加层或动画。
我想对于任何插入AVAsset什么：
- (void)addVideo:(AVAsset *)asset_in withOpacity:(float)opacity
{
// This is demo for composition of opaque videos. So we all insert video at time - 0:00
[_videoCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset_in.duration)
ofTrack:[ [asset_in tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0 ]
atTime:kCMTimeZero error:nil ];
AVMutableVideoCompositionInstruction *mutableVideoCompositionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
AVAssetTrack *assettrack_in = [ [asset_in tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0 ];
mutableVideoCompositionInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, assettrack_in.timeRange.duration);
AVMutableVideoCompositionLayerInstruction *videoCompositionLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:_videoCompositionTrack];
[videoCompositionLayerInstruction setTransform:assettrack_in.preferredTransform atTime:kCMTimeZero];
[videoCompositionLayerInstruction setOpacity:opacity atTime:kCMTimeZero];
mutableVideoCompositionInstruction.layerInstructions = @[videoCompositionLayerInstruction];
[_arrayVideoCompositionInstructions addObject:mutableVideoCompositionInstruction];
}
请注意，insertTimeRange有atTime：kCMTimeZero作为参数。所以我希望他们会放在视频作品的开头。
我尝试导出：
- (IBAction)ExportAndPlay:(id)sender
{
_mutableVideoComposition.instructions = [_arrayVideoCompositionInstructions copy];
// Create a static date formatter so we only have to initialize it once.
static NSDateFormatter *kDateFormatter;
if (!kDateFormatter) {
kDateFormatter = [[NSDateFormatter alloc] init];
kDateFormatter.dateStyle = NSDateFormatterMediumStyle;
kDateFormatter.timeStyle = NSDateFormatterShortStyle;
}
// Create the export session with the composition and set the preset to the highest quality.
AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:_mutableComposition presetName:AVAssetExportPresetHighestQuality];
// Set the desired output URL for the file created by the export process.
exporter.outputURL = [[[[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:@YES error:nil] URLByAppendingPathComponent:[kDateFormatter stringFromDate:[NSDate date]]] URLByAppendingPathExtension:CFBridgingRelease(UTTypeCopyPreferredTagWithClass((CFStringRef)AVFileTypeQuickTimeMovie, kUTTagClassFilenameExtension))];
// Set the output file type to be a QuickTime movie.
exporter.outputFileType = AVFileTypeQuickTimeMovie;
exporter.shouldOptimizeForNetworkUse = YES;
exporter.videoComposition = _mutableVideoComposition;
_mutableVideoComposition.instructions = [_arrayVideoCompositionInstructions copy];
// Asynchronously export the composition to a video file and save this file to the camera roll once export completes.
[exporter exportAsynchronouslyWithCompletionHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
switch ([exporter status]) {
case AVAssetExportSessionStatusFailed:
{
NSLog(@"Export failed: %@ %@", [[exporter error] localizedDescription],[[exporter error]debugDescription]);
}
case AVAssetExportSessionStatusCancelled:
{
NSLog(@"Export canceled");
break;
}
case AVAssetExportSessionStatusCompleted:
{
NSLog(@"Export complete!");
NSLog(@"Export URL = %@", [exporter.outputURL absoluteString]);
[self altPlayWithUrl:exporter.outputURL];
}
default:
{
NSLog(@"default");
}
}
});
}];
}
什么证明：它导出视频与第一视频后追加第二个视频，如果我选择2个视频剪辑。
这不是从我读出相同的行为：AVMutableCompositionTrack
可能任何人一些启发这个无助的羔羊？
编辑：是否有任何细节丢失，以至于没有人可以借我一只手？如果是这样，请留下评论，以便我可以做出来。