I\'m recording the screen from my iPhone device to my Mac. As a preview layer I am collecting sample buffers directly from a AVCaptureVideoDataOutput
, from whic
Another way to get from a CVPixelBufferRef to MetalTexture, you could go via a CIImage and use a CIContext with a Metal device (hopefully minimises getting the CPU involved with copying the pixel buffer);
Make sure your target metal texture is appropriately sized.
CIContext* ciContext = [CIContext contextWithMTLDevice:mtlDevice
options:[NSDictionary dictionaryWithObjectsAndKeys:@(NO),kCIContextUseSoftwareRenderer,nil]
];
id<MTLCommandBuffer> metalCommandBuffer=[mtlCommandQueue commandBufferWithUnretainedReferences];
CIImage* ciImage = [[CIImage alloc] initWithCVPixelBuffer:cvPixelBuffer];
[ciContext render:ciImage
toMTLTexture:metal_texture
commandBuffer:mtlCommandBuffer
bounds:[ciImage extent])
colorSpace:[ciImage colorSpace]];
I found a workaround for this, which keeps the 2vuy
format in the pixel buffer, but the bad thing is that you make a copy of the pixel buffer data which affects performance. I'm posting this for future reference, or if anyone else finds it useful. Basically we intercept the pixel buffer and then add attributes while copying the data.
NSDictionary *attributes = @{
@"IOSurfaceCoreAnimationCompatibility": @YES
};
CVPixelBufferRef copy = NULL;
CVPixelBufferCreate(kCFAllocatorDefault,
CVPixelBufferGetWidth(pixelBuffer),
CVPixelBufferGetHeight(pixelBuffer),
CVPixelBufferGetPixelFormatType(pixelBuffer),
(__bridge CFDictionaryRef)attributes,
©);
CVPixelBufferLockBaseAddress(pixelBuffer, kCVPixelBufferLock_ReadOnly);
CVPixelBufferLockBaseAddress(copy, 0);
void *baseAddress = CVPixelBufferGetBaseAddress(pixelBuffer);
void *copyBaseAddress = CVPixelBufferGetBaseAddress(copy);
memcpy(copyBaseAddress, baseAddress, CVPixelBufferGetDataSize(pixelBuffer));
CVPixelBufferUnlockBaseAddress(copy, 0);
CVPixelBufferUnlockBaseAddress(pixelBuffer, kCVPixelBufferLock_ReadOnly);
I've come across the same issue, the problem was not asking for Metal compatibility when configuring the AVCaptureVideoDataOutput
. I guess the system started to check this in macOS 10.13, possibly to apply some optimization when not requested.
The solution was to add the kCVPixelBufferMetalCompatibilityKey
to the videoSettings
property of AVCaptureVideoDataOutput
.
In Objective-C:
outputCapture.videoSettings = @{
/* ... */
(NSString *)kCVPixelBufferMetalCompatibilityKey: @YES
};
In Swift:
outputCapture.videoSettings = [
/* ... */
kCVPixelBufferMetalCompatibilityKey as String: true
]
I think this warrants a radar, to ask Apple to at least print a warning message when this occurs. I'll update this if I get to it.