We are using AVAssetWriter to write videos using both HEVC and H.264 encoding. Occasionally, we get reports of choppy footage in which frames appear out of order when played back on a Mac (QuickTime) or iOS device (stock Photos app). This occurs extremely unpredictably, often not starting until 20+ minutes of filming, but occasionally happening as soon as filming starts. Interestingly, users have reported the issue goes away while editing or viewing on a different platform (e.g. Linux) or in the built-in Google Drive player, but comes back as soon as the video is exported or downloaded again. When this occurs in an HEVC file, converting to H.264 seems to resolve it. I haven't found a similar fix for H.264 files. I suspect an AVAssetWriter encoding issue but haven't been able to uncover the source. Running a stream analyzer on HEVC files with this issue reveals the following error: Short-term reference picture with POC = [some number] seems to have been removed or not correctly decoded. However, running a stream analyzer on H.264 files with the same playback issue seems to show nothing wrong. At a high level, our video pipeline looks something like this: Grab a sample buffer in captureOutput(_ captureOutput: AVCaptureOutput!, didOutputVideoSampleBuffer sampleBuffer: CMSampleBuffer!) Perform some Metal rendering on that buffer Pass the resulting CVPixelBuffer to the AVAssetWriterInputPixelBufferAdaptor associated with our AVAssetWriter Example files can be found here: https://drive.google.com/drive/folders/1OjDZ3XaC-ubD5hyDiNvMQGl2NVqZbWnR?usp=sharing This includes a video file suffering this issue, the same file fixed after converting to mp4, and a screen recording of the distorted playback in QuickTime. Can anyone help point me in the right direction to solving this issue? I can provide more details as necessary.

Hello, I’ve started testing the Metal Shader Converter to convert my HLSL shaders to metallib directly, and I was wondering if the option ’-frecord-sources’ was supported in any way? Usually I’m compiling my shaders as follows (from Metal): xcrun -sdk macosx metal -c -frecord-sources shaders/shaders.metal -o shaders/shaders.air xcrun -sdk macosx metallib shaders/shaders.air -o shaders/shaders.metallib The -frecord-sources allow me to see the source when debugging and profiling a Metal frame. Now with DXC we have a similar option, I can compile a typical HLSL shader with embedded debug symbols with: dxc -T vs_6_0 -E VSMain shaders/triangle.hlsl -Fo shaders/triangle.dxil -Zi -O0 -Qembed_debug The important options here are ’-Zi` and ’-Qembed_debug’, as they make sure debug symbols are embedded in the DXIL. It seems that right now Metal Shader Converter doesn’t pass through the DXIL debug information, and I was wondering if it was possible. I’ve looked at all the options in the utility and haven’t seen anything that looked like it. Right now debug symbols in my shaders is a must-have, so I’ll explore other routes to convert my HLSL shaders to Metal (I’ve been testing spir-v cross to do the conversion, I haven’t actually tested the debug symbols yet, I’ll report back later). Thank you for your time!

I know opengl is marked as deprecated since ios12 but I have an old project using it and I want to update some feature of it then release the update version. So I'm wondering if I can still release an app using opengl to app store currently? (I know it's better to shift to MetalKit but for some reason I want to cut the cost if I can. )

I have been using MTKView to display CVPixelBuffer from the camera. I use so many options to configure color space of the MTKView/CAMetalLayer that may be needed to tonemap content to the display (CAEDRMetadata for instance). If however I use AVSampleBufferDisplayLayer, there are not many configuration options for color matching. I believe AVSampleBufferDisplayLayer uses pixel buffer attachments to determine the native color space of the input image and does the tone mapping automatically. Does AVSampleBufferDisplayLayer have any limitations compared to MTKView, or both can be used without any compromise on functionality?

Hi, I am using xcode frame capture to profile my app's shader. And I got some question about the shader per line profile statistics. Please see the two screen shot first, it is my compute shader. Begin: End: The first image is the head of the shader. The profile show's that the shader entry function takes 72.44% of the time. And at the end of the shader, the profile shows that the right brace '}' takes 60.45%. Here is my question: How to properly understand the profile data? What's the real performance data of this shader? Why the shader entry function does not take 100% of the time? Can someone help me to answer the question? Thanks! Boson

when I try to import MetalFX in visionOS, Xcode show error : No such module 'MetalFX' , but the document show visionOS is supported

After the build 4.2.9. I have a weird bug. It keep crashing and when I read the message, it display validateRenderPassDescriptor:782: failed assertion `RenderPass Descriptor Validation Texture at colorAttachment[0] has usage (0x01) which doesn't specify MTLTextureUsageRenderTarget (0x04) This happen when I run in debug mode and try to hook up the motion template. I found out that the output texture create have usage only "MTLTextureUsageShaderRead" but no "MTLTextureUsageRenderTarget" Anyone have problem like me? I uusing fxplug 4.2.9 motion 5.7 and final cut 10.7.1. running in sonoma 14.2.1

I have provided a test UIKit app which displays three different images, side by side, each inside a separate MTKView. Each image is tagged with a different color profile: Display P3 uRGB Test RGB (from an image supplied in Apple's ImageApp sample). I set up default values for all color spaces and formats. I then check if the image is tagged and, if so, I override those values with state from the tagged color space. The variables I am setting: “workingColorSpace” in the Metal CIContext, default = sRGB “workingFormat” in the Metal CIContext, default = RGBAf “outputColorSpace” in the Metal CIContext, default = displayP3 “colorPixelFormat” in the MTKView, default = bgra8Unorm “colorSpace” in a CIRenderDestination that I use in the MTKView delegate draw method The “colorSpace” default value = CGColorSpaceCreateDeviceRGB() I also set “pixelFormat” in CIRenderDestination with the MTKView.colorPixelFormat. If the image is tagged, I override the following values with the tagged colorSpace: CIContext.workingColorSpace CIContext.outputColorSpace CIRenderDestination.colorSpace If the tagged colorSpace.isWideGamutRGB = true, then I set the CIRenderDestination.colorSpace to extendedSRGB, ignoring the color space in the tagged wide gamut color space, as well as set the colorPixelFormat = bgr10_xr Results: The above scenario will properly render the DisplayP3 image, and the uRGB image. The “Test RGB” image fails: If I do not override the CIRenderDestination.colorSpace with a value from the tagged image, then the “Test RGB” image succeeds, but the “uRGB” image fails to render properly: Question: Do I have everything hooked up correctly and, if so, why does one image fail, and the other succeed? Link to sample project: https://www.dropbox.com/scl/fi/57u2fcrgdvys7jtzykzxt/ColorSpaceTest.zip?rlkey=unjeeiu7mi0wx9wfpylt78nwd&dl=0

Hello all We would like to use AMD's FidelityFx Downsampler in our custom game engine and we are having difficulties to correctly implement it for Metal due to its use of the globallycoherent keyword. We have done extensive search online but have not succeeded in finding an answer. What we have found is the largely undocumented 'volatile' keyword, so we were hypothesising that marking a texture with 'volatile' (which implies 'device volatile' since it's a texture) could have the same effect but we are far from convinced it would work. Does anyone have insights into this?

Hello, This exact question was already asked in this forum (8 years ago) but I can't find a definitive answer: Does Metal allow using the same color texture as both an input and output (color attachment) of a fragment shader? Is the behavior defined somewhere? I believe this results in undefined behavior under both DirectX and OpenGL, so I'd assume the same for Metal, but then why doesn't Metal warn me about this as it does on some many other "misconfigurations"? It also seems to work correctly in my case, as I found out by accident. Would love to get a clarification! Thanks ahead!

I am a VOIP app developer. I am planning to develop a VOIP app on iOS using WebRTC that operates in PiP (Picture-in-Picture) mode. Since MTKView (CAMetalLayer) cannot be used in PiP mode, I am considering using AVSampleBufferDisplayLayer. Regarding this, I am curious about the performance differences between CAMetalLayer and AVSampleBufferDisplayLayer. As far as I know, CAMetalLayer utilizes the GPU. Does AVSampleBufferDisplayLayer also render using the GPU? If AVSampleBufferDisplayLayer renders using the GPU, will the rendering performance be similar? => Based on tests, there seems to be no difference in CPU usage between the two, which leads me to speculate that AVSampleBufferDisplayLayer also uses the GPU. If both use the GPU and there are no performance differences, is there a significant advantage to using CAMetalLayer? Thank you in advance.

Why do I get this error almost immediately on starting my rendering pass? Multiline BlockQuote. 2024-05-29 20:02:22.744035-0500 RoomPlanExampleApp[491:10341] [] <<<< AVPointCloudData >>>> Fig assert: "_dataBuffer" at bail (AVPointCloudData.m:217) - (err=0) 2024-05-29 20:02:22.744455-0500 RoomPlanExampleApp[491:10341] [] <<<< AVPointCloudData >>>> Fig assert: "_dataBuffer" at bail (AVPointCloudData.m:217) - (err=0) 2024-05-29 20:05:54.079981-0500 RoomPlanExampleApp[491:10025] [CAMetalLayer nextDrawable] returning nil because allocation failed. 2024-05-29 20:05:54.080144-0500 RoomPlanExampleApp[491:10341] [] <<<< AVPointCloudData >>>> Fig assert: "_dataBuffer" at bail (AVPointCloudData.m:217) - (err=0)

I've got a full-screen animation of a bunch of circles filled with gradients, with plenty of (careless) overdraw, plus real-time audio processing driving the animation, plus the overhead of SwiftUI's dependency analysis, and that app uses less energy (on iPhone 13) than the Xcode "Metal Game" template which is a rotating textured cube (a trivial GPU workload). Why is that? How can I investigate further? Does CoreAnimation have access to a compositor fast-path that a Metal app cannot access? Maybe another data point: when I do the same circles animation using SwiftUI's Canvas, the energy use is "Very High" and GPU utilization is also quite high. Eventually the phone's thermal state goes "Serious" and I get a message on the device that "Charging will resume when iPhone returns to normal temperature".

We’re experiencing an issue with wrong SceneKit hit testing results in iOS 17.2 compared with iOS 16.1 when using the either Metal or OpenGLES2 engines. Tapping on a 3D model to place a SCNNode // pointInScene: tapped point let hitResults = sceneView.hitTest(pointInScene, options: nil) return hitResults.first { $0.node.name?.compare("node_name") == .orderedSame }

I am seeking clarification regarding the new device-coherent memory (buffers and textures) in Metal 3.2. Do I understand the documentation correctly that this feature allows threads from different threadgroups to update data in device memory cooperatively? The documentation mentions, "[results of operations] are visible to other threads across thread groups if you synchronize them properly." How does one do proper synchronization? From what I understand, Metal has no device-scoped barriers.

It’s great that we’ll be able to use Metal custom renderers in passthrough mode on visionOS. https://developer.apple.com/wwdc24/10092 This is a lot of complicated set-up, however. It’s also unclear how occlusion and custom algorithms / raytracing will work in tandem with scene understanding. May we have a project template and/or sample? Preferably with the C api and not just swift. This would be much-appreciated and helpful to everyone who wants this set-up. I’d like to see the whole process. Thank you for introducing this feature!

I have an issue with hand occlusion in immersive mode. I have an entry view for the app and a Metal CompositorLayer (which is the immersive volume) where I have set .upperLimbVisibility(Visibility.hidden). The problem is that when I dismiss the entry view, sometimes it hides the hands and sometimes it doesn't (randomly). @main struct AVPainterApp: App { @State var hand: Int32 = 0 var body: some Scene { WindowGroup() { ContentView(hand: $hand) } .windowResizability(.contentSize) ImmersiveSpace(id: "ImmersiveSpace") { CompositorLayer(configuration: MetalLayerConfiguration()) { layerRenderer in SpatialSceneRun(layerRenderer, hand) } } .upperLimbVisibility(Visibility.hidden) .immersionStyle(selection: .constant(.full), in: .full) } }

I've been upgrading Xcode consistently for years and have never seen Metal shaders behave differently from one version to another until now. On macOS 14.5, Xcode 16 beta, suddenly several color outputs turn out completely black where there should be color. All validation is on and nothing seems to be wrong (and hasn't been since maybe Xcode version 11). I've attached two screens. The first is the normal color scheme, the second is in Xcode 16. The settings are the exact same. Normal: Buggy with black + transparent colors (so it seems like either colors are overflowing or are all 0s)? Before I file a bug report or code level request, may I have some thoughts on how to debug this? The only clue I have is that I'm using bindless to multiply color texture samples with color values from my vertex struct. But it still fails even if I use hard-coded values for the texture samples, meaning somehow the color values are not being sent to the shader correctly? This is the most stable part of my rendering pipeline, so I'm surprised if the issue is there. Thank you.

Hi, Introducing Swift Concurrency to my Metal app has been a bit challenging as Swift Concurrency is limited by the cooperative thread pool. GPU work is obviously not CPU bound and can block forward moving progress, especially when using waitUntilCompleted on the command buffer. For concurrent render work this has the potential of under utilizing the CPU and even creating dead locks. My question is, what is the Metal's teams general recommendation when it comes to concurrency? It seems to me that Dispatch or OperationQueues are still the preferred way for Metal bound tasks in order to gain maximum performance? To integrate with Swift Concurrency my idea is to use continuations that kick off render jobs via Dispatch or Queues? Would this be the best solution to bridge async tasks with Metal work? Thanks!

Call of Duty: Black Ops 4 crashes right after launch while using Game Porting Toolkit 2. The following errors by wine-preloader can be found in the Console: error 16:25:59.318998+0300 wine-preloader Unsupported API: IDXGISwapChain3::SetColorSpace1 error 16:26:00.039271+0300 wine-preloader Unsupported API: D3D11 timestamp query