Hi, I have found that when creating a MLMultiArray from an IOSurface backed CVPixelBuffer that the striding across the last dimension gets fixed to a multiple of 32. Say I have some objective-c code that creates a MLMultiArray from a CVPixelBuffer like so; CVPixelBufferRef pixelBuffer = NULL; NSDictionary* pixelBufferAttributes = @{ (id)kCVPixelBufferIOSurfacePropertiesKey: @{} }; // Since shape == [2, 3, 4], width is 4 (= shape[2]) and height is 6 (= shape[0] * shape[1]). CVPixelBufferCreate(kCFAllocatorDefault, 4, 6, kCVPixelFormatType_OneComponent16Half, (__bridge CFDictionaryRef)pixelBufferAttributes, &pixelBuffer); MLMultiArray *multiArray = [[MLMultiArray alloc] initWithPixelBuffer:pixelBuffer shape:@[@2, @3, @4]]; This successfully creates a MLMultiArray from an IOSurface backed CVPixelBuffer. If I inspect the MLMultiArray, I see that the shape and strides are the following; //_shape: [2, 3, 4] //_strides: [96, 32, 1] To me it makes more sense that the strides should be; //_strides: [12,4,1] I assume that this is likely hardcoded to be multiples of 32 somewhere in the MLMultiArray initialisation code and since strides is a read only member variable of MLMultiArray it cannot be changed explicitly. Is it possible to set the striding explicitly in any way, or create an MLMutliArray from IOSurface backed buffer that allows the striding to be set differently ?

Hi there, I am trying to create a CoreML Custom layer that runs on the GPU, using Objective-C for CoreML setup and Metal for GPU programming. I have created the CoreML model with the custom layer and can successfully execute on the GPU, I wish to create an MTLBuffer from an input MTLTexture in my setup actual GPU execution, although I can't seem to do so, or get access to the memory address to the MTLTexture memory. When defining a custom layer in CoreML to run on the GPU, the following function needs to be defined, with the given prototype; (BOOL) encodeToCommandBuffer:(id<MTLCommandBuffer>)commandBuffer inputs:(NSArray<id<MTLTexture>> *)inputs outputs:(NSArray<id<MTLTexture>> *)outputs error:(NSError *__autoreleasing _Nullable *)error{ // GPU Setup, moving data, encoding, execution and so on here } Here, the inputs are passed as an NSArray of MTLTexture's, we then pass these texture's on to the Metal Shader for computation. My problem is that I want to pass an MTLBuffer to the Metal Shader, which points to the input data, say inputs[0], but I am having troubling copying the input MTLTexture to an MTLBuffer. I have tried using the MTLBlitCommandEncoder to copy the data from the MTLTexture to an MTLBuffer like so; id<MTLBuffer> test_buffer = [command_PSO.device newBufferWithLength:(8) options:MTLResourceStorageModeShared]; id <MTLBlitCommandEncoder> blitCommandEncoder = [commandBuffer blitCommandEncoder]; [blitCommandEncoder copyFromTexture:inputs[0] sourceSlice:0 sourceLevel:0 sourceOrigin:MTLOriginMake(0, 0, 0) sourceSize:MTLSizeMake(1, 1, 1) toBuffer:test_buffer destinationOffset:0 destinationBytesPerRow:8 destinationBytesPerImage:8]; [blitCommandEncoder endEncoding]; The above example should copy a single pixel from the MTLTexture, inputs[0], to the MTLBuffer, test_buffer, but this is not the case. MTLTextures, getBytes also doesn't work as the inputs have MTLResourceStorageModePrivate set. When I inspect the input MTLTexture I note that the attribute buffer = <null> and I'm wondering if this could be an issue since the texture was not created from a buffer, and perhaps doesn't store the address to memory easily, but surely we should be able to get the memory address somewhere? For further reference, here is the input MTLTexture definition; <CaptureMTLTexture: 0x282469500> -> <AGXA14FamilyTexture: 0x133d9bb00> label = <none> textureType = MTLTextureType2DArray pixelFormat = MTLPixelFormatRGBA16Float width = 8 height = 1 depth = 1 arrayLength = 1 mipmapLevelCount = 1 sampleCount = 1 cpuCacheMode = MTLCPUCacheModeDefaultCache storageMode = MTLStorageModePrivate hazardTrackingMode = MTLHazardTrackingModeTracked resourceOptions = MTLResourceCPUCacheModeDefaultCache MTLResourceStorageModePrivate MTLResourceHazardTrackingModeTracked usage = MTLTextureUsageShaderRead MTLTextureUsageShaderWrite shareable = 0 framebufferOnly = 0 purgeableState = MTLPurgeableStateNonVolatile swizzle = [MTLTextureSwizzleRed, MTLTextureSwizzleGreen, MTLTextureSwizzleBlue, MTLTextureSwizzleAlpha] isCompressed = 0 parentTexture = <null> parentRelativeLevel = 0 parentRelativeSlice = 0 buffer = <null> bufferOffset = 0 bufferBytesPerRow = 0 iosurface = 0x0 iosurfacePlane = 0 allowGPUOptimizedContents = YES label = <none>