我每 N 个视频帧从CMSampleBufferRef视频缓冲区获取一个UIImage ，例如：
- (void)imageFromVideoBuffer:(void(^)(UIImage* image))completion {
CMSampleBufferRef sampleBuffer = _myLastSampleBuffer;
if (sampleBuffer != nil) {
CFRetain(sampleBuffer);
CIImage *ciImage = [CIImage imageWithCVPixelBuffer:CMSampleBufferGetImageBuffer(sampleBuffer)];
_lastAppendedVideoBuffer.sampleBuffer = nil;
if (_context == nil) {
_context = [CIContext contextWithOptions:nil];
}
CVPixelBufferRef buffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CGImageRef cgImage = [_context createCGImage:ciImage fromRect:
CGRectMake(0, 0, CVPixelBufferGetWidth(buffer), CVPixelBufferGetHeight(buffer))];
__block UIImage *image = [UIImage imageWithCGImage:cgImage];
CGImageRelease(cgImage);
CFRelease(sampleBuffer);
if(completion) completion(image);
return;
}
if(completion) completion(nil);
}
XCode 和 Instruments 检测到内存泄漏，但我无法摆脱它。我像往常一样发布 CGImageRef 和 CMSampleBufferRef ：
CGImageRelease(cgImage);
CFRelease(sampleBuffer);
[更新]
我输入了AVCapture输出回调来获取sampleBuffer.
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
if (captureOutput == _videoOutput) {
_lastVideoBuffer.sampleBuffer = sampleBuffer;
id<CIImageRenderer> imageRenderer = _CIImageRenderer;
dispatch_async(dispatch_get_main_queue(), ^{
@autoreleasepool {
CIImage *ciImage = nil;
ciImage = [CIImage imageWithCVPixelBuffer:CMSampleBufferGetImageBuffer(sampleBuffer)];
if(_context==nil) {
_context = [CIContext contextWithOptions:nil];
}
CGImageRef processedCGImage = [_context createCGImage:ciImage
fromRect:[ciImage extent]];
//UIImage *image=[UIImage imageWithCGImage:processedCGImage];
CGImageRelease(processedCGImage);
NSLog(@"Captured image %@", ciImage);
}
});
泄漏的代码是createCGImage:ciImage：
CGImageRef processedCGImage = [_context createCGImage:ciImage
fromRect:[ciImage extent]];
甚至有一个autoreleasepool,CGImageRelease的CGImage引用和一个CIContext作为实例属性。
这似乎与此处解决的问题相同：Can't save CIImage to file on iOS without memory leaks
[更新]泄漏似乎是由于一个错误。这个问题 在 iOS 9 的 CIContext createCGImage 上的内存泄漏中有很好的描述？
一个示例项目显示了如何重现此泄漏：http ://www.osamu.co.jp/DataArea/VideoCameraTest.zip
最后的评论保证
看起来他们在 9.1b3 中修复了这个问题。如果有人需要适用于 iOS 9.0.x 的解决方法，我可以使用它：
在测试代码中（在这种情况下为 Swift）：
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error)
{
if (error) return;
__block NSString *filePath = [NSTemporaryDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:@"ipdf_pic_%i.jpeg",(int)[NSDate date].timeIntervalSince1970]];
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
dispatch_async(dispatch_get_main_queue(), ^
{
@autoreleasepool
{
CIImage *enhancedImage = [CIImage imageWithData:imageData];
if (!enhancedImage) return;
static CIContext *ctx = nil; if (!ctx) ctx = [CIContext contextWithOptions:nil];
CGImageRef imageRef = [ctx createCGImage:enhancedImage fromRect:enhancedImage.extent format:kCIFormatBGRA8 colorSpace:nil];
UIImage *image = [UIImage imageWithCGImage:imageRef scale:1.0 orientation:UIImageOrientationRight];
[[NSFileManager defaultManager] createFileAtPath:filePath contents:UIImageJPEGRepresentation(image, 0.8) attributes:nil];
CGImageRelease(imageRef);
}
});
}];
iOS9.0 的解决方法应该是
extension CIContext {
func createCGImage_(image:CIImage, fromRect:CGRect) -> CGImage {
let width = Int(fromRect.width)
let height = Int(fromRect.height)
let rawData = UnsafeMutablePointer<UInt8>.alloc(width * height * 4)
render(image, toBitmap: rawData, rowBytes: width * 4, bounds: fromRect, format: kCIFormatRGBA8, colorSpace: CGColorSpaceCreateDeviceRGB())
let dataProvider = CGDataProviderCreateWithData(nil, rawData, height * width * 4) {info, data, size in UnsafeMutablePointer<UInt8>(data).dealloc(size)}
return CGImageCreate(width, height, 8, 32, width * 4, CGColorSpaceCreateDeviceRGB(), CGBitmapInfo(rawValue: CGImageAlphaInfo.PremultipliedLast.rawValue), dataProvider, nil, false, .RenderingIntentDefault)!
}
}