[我正在尝试在Mac OS X上镜像从网络摄像头收到的视频。接收视频缓冲区后,我想避免进行手动翻转/转换。因此,我想设置AVCaptureSession
,以使AVFoundation自身镜像在captureOutput
的AVCaptureVideoDataOutputSampleBufferDelegate
方法中接收的视频缓冲区。我不想使用预览层。
在iMac(10.8.5)上,要镜像视频,在设置AVCaptureConnection isVideoMirroringSupported
属性之前,已成功测试videoMirrored
。但是captureOutput
委托中接收的视频缓冲区未镜像。
注意:当我按照this SO回答时,iOS上的视频镜像成功。但这对Mac OS X没有帮助。
使用的代码如下。这篇文章没有进行错误检查。
//create session
_session = [[AVCaptureSession alloc] init];
//get capture device
_device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
//create sesion input
NSError * error;
_sessionInput = [AVCaptureDeviceInput deviceInputWithDevice:_device error:&error];
//create session output
_sessionOutput = [[AVCaptureVideoDataOutput alloc] init];
[_sessionOutput setAlwaysDiscardsLateVideoFrames:YES];
[[_sessionOutput connectionWithMediaType:AVMediaTypeVideo] setEnabled:YES];
NSDictionary *videoSettings = [NSDictionary dictionaryWithObject: [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey];
[_sessionOutput setVideoSettings:videoSettings];
//serial queue to process video frames
dispatch_queue_t videoOutputQueue = dispatch_queue_create("deviceeraQueue", DISPATCH_QUEUE_SERIAL);
[_sessionOutput setSampleBufferDelegate:self queue:videoOutputQueue];
//begin session configuration
[_session beginConfiguration ];
//input and output for session
if( [_session canAddInput:_sessionInput]) {
[_session addInput:_sessionInput];
}
if( [_session canAddOutput:_sessionOutput]) {
[_session addOutput:_sessionOutput];
}
//set video mirroring
AVCaptureConnection* avConnection = [_sessionOutput connectionWithMediaType:AVMediaTypeVideo];
if( [avConnection isVideoMirroringSupported]) {
avConnection.videoMirrored = YES;
NSLog(@"Video mirroring Support: YES"); // this line is printed
} else {
NSLog(@"Video mirroring Support: NO");
}
//set session preset
[_session setSessionPreset:AVCaptureSessionPreset640x480];
[ _session commitConfiguration ];
...........
...........
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
.........
//sampleBuffer is not mirrored video
........
重要性较轻1-尽管使用C ++,但我也尝试研究OpenCV的VideoCapture实现以镜像视频。但是,OpenCV不能从Mac镜像视频(使用翻转)。左边是libVlc / V4L。
次要重要性2-在this 2010 wwdc苹果演示文稿(3Mb pdf)的幻灯片73中,提到“ AVCaptureVideoDataOutput”连接不支持setVideoOrientation
。但是在2013年,苹果docs已更新并支持此方法。
您可以在预览层上添加变换以翻转帧的x值,然后再进入预览窗口。
[[self previewLayer] setTransform:CATransform3DMakeScale(-1, 1, 1)];
然后,您可以在导出会话中运行录制的视频并进行相同的转换。这样,视频预览将与最终录制的视频匹配。有点骇人听闻,但结果却相同。
为什么很简单,为什么要破解呢?只需自动设置AVCaptureConnection的AdjustVideoMirroring,然后手动设置即可。
aPreviewLayer.connection.automaticallyAdjustsVideoMirroring = NO;
aPreviewLayer.connection.videoMirrored = YES;
Swift 5版本的“ÞorvaldurRúnarsson”答案:
previewLayer.connection?.automaticallyAdjustsVideoMirroring = false
previewLayer.connection?.isVideoMirrored = true