我AVCaptureMovieFileOutput用来录制一些视频。我显示了预览层，使用AVLayerVideoGravityResizeAspectFill它稍微放大。我遇到的问题是最终视频更大，包含在预览期间不适合屏幕的额外图像。
这是预览和生成的视频
有没有一种方法可以指定CGRect我想从视频中剪切的内容AVAssetExportSession？
编辑 - -
当我对它应用 aCGAffineTransformScale时，AVAssetTrack它会放大视频，并用它的AVMutableVideoComposition renderSize设置view.bounds裁剪掉末端。太好了，只剩下1个问题了。视频的宽度没有拉伸到正确的宽度，它只是被黑色填充。
编辑 2 ---- 建议的问题/答案不完整..
我的一些代码：
在我的- (void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error方法中，我可以裁剪和调整视频大小。
- (void)flipAndSave:(NSURL *)videoURL withCompletionBlock:(void(^)(NSURL *returnURL))completionBlock
{
AVURLAsset *firstAsset = [AVURLAsset assetWithURL:videoURL];
// 1 - Create AVMutableComposition object. This object will hold your AVMutableCompositionTrack instances.
AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];
// 2 - 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];
// 2.1 - Create AVMutableVideoCompositionInstruction
AVMutableVideoCompositionInstruction *mainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
mainInstruction.timeRange = CMTimeRangeMake(CMTimeMakeWithSeconds(0, 600), firstAsset.duration);
// 2.2 - Create an AVMutableVideoCompositionLayerInstruction for the first track
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;
}
// [firstlayerInstruction setTransform:firstAssetTrack.preferredTransform atTime:kCMTimeZero];
// [firstlayerInstruction setCropRectangle:self.view.bounds atTime:kCMTimeZero];
CGFloat scale = [self getScaleFromAsset:firstAssetTrack];
firstTransform = CGAffineTransformScale(firstTransform, scale, scale);
[firstlayerInstruction setTransform:firstTransform atTime:kCMTimeZero];
// 2.4 - Add instructions
mainInstruction.layerInstructions = [NSArray arrayWithObjects:firstlayerInstruction,nil];
AVMutableVideoComposition *mainCompositionInst = [AVMutableVideoComposition videoComposition];
mainCompositionInst.instructions = [NSArray arrayWithObject:mainInstruction];
mainCompositionInst.frameDuration = CMTimeMake(1, 30);
// CGSize videoSize = firstAssetTrack.naturalSize;
CGSize videoSize = self.view.bounds.size;
BOOL isPortrait_ = [self isVideoPortrait:firstAsset];
if(isPortrait_) {
videoSize = CGSizeMake(videoSize.height, videoSize.width);
}
NSLog(@"%@", NSStringFromCGSize(videoSize));
mainCompositionInst.renderSize = videoSize;
// 3 - Audio track
AVMutableCompositionTrack *AudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID:kCMPersistentTrackID_Invalid];
[AudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, firstAsset.duration)
ofTrack:[[firstAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:kCMTimeZero error:nil];
// 4 - Get path
NSString *outputPath = [[NSString alloc] initWithFormat:@"%@%@", NSTemporaryDirectory(), @"cutoutput.mov"];
NSURL *outputURL = [[NSURL alloc] initFileURLWithPath:outputPath];
NSFileManager *manager = [[NSFileManager alloc] init];
if ([manager fileExistsAtPath:outputPath])
{
[manager removeItemAtPath:outputPath error:nil];
}
// 5 - Create exporter
AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition
presetName:AVAssetExportPresetHighestQuality];
exporter.outputURL=outputURL;
exporter.outputFileType = AVFileTypeQuickTimeMovie;
exporter.shouldOptimizeForNetworkUse = YES;
exporter.videoComposition = mainCompositionInst;
[exporter exportAsynchronouslyWithCompletionHandler:^{
switch ([exporter status])
{
case AVAssetExportSessionStatusFailed:
NSLog(@"Export failed: %@ : %@", [[exporter error] localizedDescription], [exporter error]);
completionBlock(nil);
break;
case AVAssetExportSessionStatusCancelled:
NSLog(@"Export canceled");
completionBlock(nil);
break;
default: {
NSURL *outputURL = exporter.outputURL;
dispatch_async(dispatch_get_main_queue(), ^{
completionBlock(outputURL);
});
break;
}
}
}];
}