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AirPlay mirroring freezes after switching away from full-screen video in Photos
Hello Apple team, This issue is reproducible with AirPlay mirroring from an iPhone. When a video is played full screen in the Photos app and the user then switches to another app or enters the multitasking flow, the mirrored video output freezes completely on the receiving device. The AirPlay session appears to remain connected, but the receiver keeps displaying the last video frame and the mirrored stream does not recover automatically. Stopping and restarting AirPlay mirroring is required to recover. Environment: Sender: iPhone, iOS [26.5] Receiver: AirPlay receiver device/app The same behavior can also be reproduced when mirroring from iPhone to a Mac Source app: Photos Content: local video played in full screen Steps to reproduce: Start AirPlay mirroring from an iPhone to an AirPlay receiver. Open the Photos app on the iPhone. Play a local video in full screen. While the video is playing, switch to another app or enter the multitasking flow. Observe the mirrored output on the receiver side. Video Recording: https://drive.google.com/file/d/1X9Mj9EB4IYZXjDdCaqrXfgg1PpbhZoUN/view?usp=sharing Expected behavior: AirPlay mirroring should continue smoothly after the app switch, or recover automatically when the source video/app state changes. Actual behavior: The mirrored video freezes completely. The AirPlay connection remains active, but no new video frames are rendered on the receiver side. The stream does not recover until AirPlay mirroring is stopped and restarted. Could Apple confirm whether this is a known AirPlay mirroring issue? Is there any recommended workaround, receiver-side handling, or additional diagnostic information that should be collected for this case?
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Metadata updated for exported photo items
Hi, I have been trying to capture the EXIF metadata using JS from the images while selecting them in a web-app using simple file/photo picker. There's an option to adjust the original datetime for any image in iOS photos app and that's where my query starts. Whenever and image with adjusted date is selected in the browser using the photo picker, the image being given to the browser contains the adjusted date as the original date without any metadata tag containing the original timestamp from the image. Is there any way to capture the original timestamp in a web-app from the image even after it's timestamp is adjusted in IOS photos app? Also, if I may ask what might be the intended reason for this functionality since I could not get hands on something concrete and convincing about this, specially considering that we are able to adjust the timestamp to a value way ahead in the future as well. Any help and support is highly appreciated!
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Best practice for rapid sequential Live Photo captures with AVCapturePhotoOutput?
Hi everyone, I’m working on a camera app as a learning project and have reached a point where I’m trying to better understand the intended architecture for Live Photo capture using AVCapturePhotoOutput. The app currently supports: Live Photos Depth data Location metadata Multiple lens presets on a virtual multi-camera device Everything is working well, but I’m now thinking about capture throughput and rapid shutter presses. Right now, my implementation is fairly conservative. I wait for a Live Photo capture to finish processing and importing before allowing another capture. This is reliable, but it doesn’t feel particularly camera-like when compared to Apple’s Camera app. One observation from field testing caught my attention: I took a Live Photo, immediately switched lenses, then took another Live Photo. When I viewed the first Live Photo later, the movie portion included the lens-switching actions that occurred after I pressed the shutter. That made me realize that I may be thinking about the capture lifecycle incorrectly. My questions are: When using AVCapturePhotoOutput with Live Photos enabled, what is the earliest point at which a capture can be considered “safely secured”? Is it expected that apps wait for PhotoKit import to complete before accepting another Live Photo capture request? If supporting rapid sequential shutter presses, is the recommended approach to queue capture requests and process them one at a time? Are there any best practices around lens changes or camera reconfiguration while a Live Photo is still being captured or processed? I’m not looking for details about the implementation of Apple’s Camera app. I’m mainly trying to understand the recommended approach when working with the public AVFoundation APIs. I’d appreciate any guidance, documentation references, or examples from developers who have worked through similar problems. Thanks!
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Reference Mode custom presets do not reproduce the same grayscale response as built-in Apple presets
I found an issue with macOS Reference Modes where a recreated custom preset does not match the grayscale response of the original Apple-provided preset, even when all visible settings appear to be identical. For example, when duplicating the built-in Apple Display P3-600 nits Reference Mode preset, the duplicated preset does not produce the same grayscale luminance response as the original system preset. The comparison is performed under the same physical display brightness setting. The difference is not caused by different brightness levels. The native Reference Mode preset and the recreated preset are tested at the same display brightness, but the grayscale response is still different. The same behavior also occurs when manually creating a new Reference Mode preset with equivalent parameters, including using Pure Gamma settings. Even when the gamma value and other visible parameters are matched, the grayscale transfer function in the shadow region does not match the original Apple preset. The difference can be observed using grayscale test patterns, including: BarsAndBlack_16bit.TIFF CT ColorBar test pattern With these test images, the recreated preset shows lifted dark tones compared with the original Apple Display P3-600 nits preset. The darker grayscale steps become brighter, indicating that the EOTF/grayscale response is not identical between the built-in preset and the recreated preset. This behavior can be reproduced using the built-in macOS Preview application. Opening the same test image and switching between the native Reference Mode preset and the recreated preset shows differences in the black level and shadow grayscale response. The issue can be reproduced on both macOS 26.4 and macOS 15. Environment: macOS: 26.4 (also reproducible on macOS 15) Mac: 14-inch MacBook Pro Display: Built-in XDR Display Reference Mode tested: Apple Display P3-600 nits The main question is: When there is a difference between the built-in Apple Reference Mode preset and a recreated preset with the same visible parameters, which one represents the intended and accurate gamma/EOTF response? Specifically: Is the built-in Apple Display P3-600 nits Reference Mode using additional internal calibration data or hidden parameters that are not exposed in the Reference Mode configuration UI? Is the recreated preset actually applying the requested gamma curve correctly, while the Apple preset includes additional processing? Or is the Apple built-in preset the accurate reference implementation, and the recreated preset cannot reproduce it because some internal display calibration information is unavailable? Is there a documented way to create a custom Reference Mode preset that exactly matches the grayscale response of an Apple system preset? Thank you.
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MusicKit with Music Understanding?
Is there some bridge we could use to have Music Understanding use a song via MusicKit. it would be great to be able to link a music score to a song in MusicKit, then use the features in music understanding to link a live playback with the score.
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PhotogrammetrySession(input: [PhotogrammetrySample]) Hangs or terminates
Providing a response and feedback to this: https://origin-devforums.apple.com/forums/thread/827311 and https://developer.apple.com/forums/thread/827043?page=1#889020022 I have a created a feedback/bug report with ID FB22823733 Feedback Report: I have created a feedback report as well like recommended with this ID: FB22823733, with more elaborate images of my implementation, also see here More clarity: Yes, this is for an iOS app(iOS 18+) but testing and debugging on Xcode(MacOS 15.7.7, M4 24GB), which traps or hangs on getting to [PhotogrammetrySample] even while using the lazy sequence and the contentsOf as specified in your docs. I also tried using the PhotogrammetrySession folder run but its still failed with : CoreOC.PhotogrammetrySession.Error 6 and I understand to mean alignment failed. What can be done or do you guys expose any functions that can be used to aid, or handle these internally, can't find any internally. The ObjectMasks are actually segmentation masks from an ML algorithm . To replicate try calling PhotogrammetrySession(input: [PhotogrammetrySample]) with contentsOf as captured on your documentation, even with like 30 image set or is there something I'm missing.
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PHAssetResourceUploadJobChangeRequest doesn't upload iCloud-optimized photos — is this expected?
I'm implementing PHBackgroundResourceUploadExtension to back up photos and videos to our cloud storage service. During testing, I observed that iCloud-optimized photos (where the full-resolution original is stored in iCloud, not on device) do not upload. The upload job appears to silently skip these assets. Questions: Is this behavior intentional/documented? I couldn't find explicit mention of this limitation. If the device only has the optimized/thumbnail version locally, does the system: - Automatically download the full-resolution asset from iCloud before uploading? - Skip the asset entirely? - Return an error via PHAssetResourceUploadJobChangeRequest? For a complete backup solution, should we: - Pre-fetch full-resolution assets using PHAssetResourceManager.requestData(for:options:) before creating upload jobs? - Use a hybrid approach (this extension for local assets + separate logic for iCloud-only assets)? Environment: iOS 26, Xcode 18
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Restore certain photo resources
Through the Photos framework, we can access (and thus backup) resources the user created in Photos, such as Adjustments.plist, AdjustmentsSecondary.data, .aae files and more. Is there any way to restore those resources back into the Photos library? (e.g., similar to dropping a combination of .heic and .mov file to restore a Live Photo)
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List of RAW 9 bugs
Thanks for adding CoreML into the Apple RAW decoder. I'm excited with what it can bring. But I'm having a number of issues with it. My code base is written in Objective-C, and I'm using my custom MTKView. Now when I enabled RAW 9 support, the render is extremely slow (instant vs seconds). The UI would appear to hang with a spinning color wheel. It feels like CoreML processing is being delegated in the rendering thread, which runs on the main queue. How can I improve performance? As someone has reported, there is a black horizontal line in the middle of the image. The image that I was testing came from Fuji X-T5. If I enable EDR (Extended Dynamic Range), RAW 9 stops rendering, and will return ANE error. My app does HDR rendering of RAW files. I cannot get something like Sony A7R IV ARW image to load. Same ANE error. Is there a memory setting I need to tweak? When I render the X-T5 image, the colors appear to be overly saturated, which is different from the result of RAW 8. I cannot speak for the color rendering of other types of RAW files. I was told code base with Catalyst (and perhaps Swift) works without issue, other than being slow (except for large RAW files), but there seems to be an issue with Objective-C?
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How to upload large videos with PHAssetResourceUploadJobChangeRequest?
I'm implementing a PHBackgroundResourceUploadExtension to back up photos and videos from the user's library to our cloud storage service. Our existing upload infrastructure uses chunked uploads for large files (splitting videos into smaller byte ranges and uploading each chunk separately). This approach: Allows resumable uploads if interrupted Stays within server-side request size limits Provides granular progress tracking Looking at the PHAssetResourceUploadJobChangeRequest.createJob(destination:resource:) API, I don't see a way to specify byte ranges or create multiple jobs for chunks of the same resource. Questions: Does the system handle large files (1GB+) automatically under the hood, or is there a recommended maximum file size for a single upload job? Is there a supported pattern for chunked/resumable uploads, or should the destination URL endpoint handle the entire file in one request? If our server requires chunked uploads (e.g., BITS protocol with CreateSession → Fragment → CloseSession), is this extension the right mechanism, or should we use a different approach for large videos? Any guidance on best practices for large asset uploads would be greatly appreciated. Environment: iOS 26, Xcode 18
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MusicKit.js / WKWebView: Are audible hitches during seek a known WebKit or Apple Media Stack limitation?
We are building a musician practice application that uses MusicKit.js inside a WKWebView on iOS and macOS. One of our core use cases is musical looping, where playback repeatedly seeks back to a loop start position while a song is playing. A typical loop length is 1-4 seconds, making interruptions that might be acceptable for general media playback very noticeable in our use case. For looping we currently use MusicKit’s seekToTime() API. We have also experimented with audioElement.fastSeek() and directly setting audioElement.currentTime. In all cases, seeking to a nearby position during playback produces an audible hitch or pause, even when the destination appears to already be buffered. We have observed similar interruptions when changing the playback rate during playback. For comparison, the same JavaScript bridge architecture running in a Chromium-based WebView on Android exhibits significantly smoother seek behavior and supports near-seamless looping. At this point, the WebView media stack appears to be the primary platform difference we have identified. We are currently using MusicKit.js v2. We are aware that v3 is available, but have not found anything suggesting this behavior has changed. As part of our investigation, we also experimented with Apple’s native MusicKit APIs. We observed that seeking and playback-rate changes can still produce audible interruptions, although playback-rate changes behave noticeably better than our MusicKit.js / HTML audio implementation. This led us to wonder whether the behavior originates from the underlying Apple media pipeline rather than MusicKit.js itself. Our questions are: Is it expected that seeking during playback, whether through seekToTime(), fastSeek(), or currentTime, causes the playback pipeline to be interrupted or rebuilt on Apple platforms? Are there known differences in WebKit’s media pipeline, buffering, or seek handling that would explain why the same implementation exhibits smoother seek behavior in a Chromium-based WebView? If so, are there recommended WebKit, WKWebView, or MusicKit.js techniques to achieve smoother, near-seamless looping? Given that we observe similar, though less pronounced, behavior when using native MusicKit APIs, is this a known characteristic or limitation of the underlying Apple media stack? If so, are there any APIs or implementation patterns recommended for applications that require tight musical looping and low-latency seeks? Any guidance would be greatly appreciated. Our goal is to provide musicians with seamless looping for practice and transcription, where even very small interruptions are noticeable.
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CIContext memoryLimit tips?
I would like to use the memory limit during interactive editing on iOS to decrease jetsam risk. However, I'm unsure of what to set it to. Do you have a recommendation as a fraction of physical memory? I have set the extended virtual memory entitlement, but I don't know what fraction of physical memory (or more) that entitlement enables - perhaps I should use a larger memory limit for M1-based iPads?
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List of RAW 9 bugs
Thanks for adding CoreML into the Apple RAW decoder. I'm excited with what it can bring. But I'm having a number of issues with it. My code base is written in Objective-C, and I'm using my custom MTKView. Now when I enabled RAW 9 support, the render is extremely slow (instant vs seconds). The UI would appear to hang with a spinning color wheel. It feels like CoreML processing is being delegated in the rendering thread, which runs on the main queue. How can I improve performance? As someone has reported, there is a black horizontal line in the middle of the image. The image that I was testing came from Fuji X-T5. If I enable EDR (Extended Dynamic Range), RAW 9 stops rendering, and will return ANE error. My app does HDR rendering of RAW files. I cannot get something like Sony A7R IV ARW image to load. Same ANE error. Is there a memory setting I need to tweak? When I render the X-T5 image, the colors appear to be overly saturated, which is different from the result of RAW 8. I cannot speak for the color rendering of other types of RAW files. I was told code base with Catalyst (and perhaps Swift) works without issue, other than being slow (except for large RAW files), but there seems to be an issue with Objective-C?
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Extended Dynamic Range support
My app currently supports display and editing of RAW files in HDR mode (Extended Dynamic Range). I came across 2 issues: In HDR mode, if I am using the default boostAmount = 1.0, then some of the highlight colors will shift. Like a clear blue sky becomes a light gray / light purple sky. I've to set boostAmount = 0.0 to avoid this problem. Is this a bug or is there a way to keep the Apple colors and not having this issue? The Shadow and highlight filter does not appear to work correctly in HDR mode, I've it hooked up in the linearSpaceFilter. Would be nice if you guys can introduce a spatial aware shadow & highlight filter.
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CIContext memoryTarget defaults and Extended Virtual Addressing on macOS
Is the memoryLimit option mentioned in WWDC26 session 305 the same option as CIContextOption.memoryTarget? The session says the default memory target on iOS is 256 MB. What is the default memoryTarget on macOS? Also, the session recommends the Extended Virtual Addressing entitlement for interactive RAW editing. That entitlement does not appear to be available for macOS, so does Core Image automatically use a larger intermediate cache budget on macOS? Should memoryTarget be used only for export contexts, or can/should it also be tuned for interactive editing contexts with cacheIntermediates enabled? Thanks!
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List of RAW 9 bugs
Thanks for adding CoreML into the Apple RAW decoder. I'm excited with what it can bring. But I'm having a number of issues with it. My code base is written in Objective-C, and I'm using my custom MTKView. Now when I enabled RAW 9 support, the render is extremely slow (instant vs seconds). The UI would appear to hang with a spinning color wheel. It feels like CoreML processing is being delegated in the rendering thread, which runs on the main queue. How can I improve performance? As someone has reported, there is a black horizontal line in the middle of the image. The image that I was testing came from Fuji X-T5. If I enable EDR (Extended Dynamic Range), RAW 9 stops rendering, and will return ANE error. My app does HDR rendering of RAW files. I cannot get something like Sony A7R IV ARW image to load. Same ANE error. Is there a memory setting I need to tweak? When I render the X-T5 image, the colors appear to be overly saturated, which is different from the result of RAW 8. I cannot speak for the color rendering of other types of RAW files. I was told code base with Catalyst (and perhaps Swift) works without issue, other than being slow (except for large RAW files), but there seems to be an issue with Objective-C?
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Interactive Performance Tips?
Aside from setting inputScaleFactor and using cacheIntermediates, what are the most important things to do to get great interactive performance with Core Image (both when constructing a CIImage from URL and using CIRAWFilter). Perhaps CIImage lifetimes or how they are mutated? Alternatively, what patterns (again other than inputScaleFactor / cacheIntermediates) most hurt performance?
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AirPlay mirroring freezes after switching away from full-screen video in Photos
Hello Apple team, This issue is reproducible with AirPlay mirroring from an iPhone. When a video is played full screen in the Photos app and the user then switches to another app or enters the multitasking flow, the mirrored video output freezes completely on the receiving device. The AirPlay session appears to remain connected, but the receiver keeps displaying the last video frame and the mirrored stream does not recover automatically. Stopping and restarting AirPlay mirroring is required to recover. Environment: Sender: iPhone, iOS [26.5] Receiver: AirPlay receiver device/app The same behavior can also be reproduced when mirroring from iPhone to a Mac Source app: Photos Content: local video played in full screen Steps to reproduce: Start AirPlay mirroring from an iPhone to an AirPlay receiver. Open the Photos app on the iPhone. Play a local video in full screen. While the video is playing, switch to another app or enter the multitasking flow. Observe the mirrored output on the receiver side. Video Recording: https://drive.google.com/file/d/1X9Mj9EB4IYZXjDdCaqrXfgg1PpbhZoUN/view?usp=sharing Expected behavior: AirPlay mirroring should continue smoothly after the app switch, or recover automatically when the source video/app state changes. Actual behavior: The mirrored video freezes completely. The AirPlay connection remains active, but no new video frames are rendered on the receiver side. The stream does not recover until AirPlay mirroring is stopped and restarted. Could Apple confirm whether this is a known AirPlay mirroring issue? Is there any recommended workaround, receiver-side handling, or additional diagnostic information that should be collected for this case?
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24
Activity
6h
Metadata updated for exported photo items
Hi, I have been trying to capture the EXIF metadata using JS from the images while selecting them in a web-app using simple file/photo picker. There's an option to adjust the original datetime for any image in iOS photos app and that's where my query starts. Whenever and image with adjusted date is selected in the browser using the photo picker, the image being given to the browser contains the adjusted date as the original date without any metadata tag containing the original timestamp from the image. Is there any way to capture the original timestamp in a web-app from the image even after it's timestamp is adjusted in IOS photos app? Also, if I may ask what might be the intended reason for this functionality since I could not get hands on something concrete and convincing about this, specially considering that we are able to adjust the timestamp to a value way ahead in the future as well. Any help and support is highly appreciated!
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18
Activity
9h
Best practice for rapid sequential Live Photo captures with AVCapturePhotoOutput?
Hi everyone, I’m working on a camera app as a learning project and have reached a point where I’m trying to better understand the intended architecture for Live Photo capture using AVCapturePhotoOutput. The app currently supports: Live Photos Depth data Location metadata Multiple lens presets on a virtual multi-camera device Everything is working well, but I’m now thinking about capture throughput and rapid shutter presses. Right now, my implementation is fairly conservative. I wait for a Live Photo capture to finish processing and importing before allowing another capture. This is reliable, but it doesn’t feel particularly camera-like when compared to Apple’s Camera app. One observation from field testing caught my attention: I took a Live Photo, immediately switched lenses, then took another Live Photo. When I viewed the first Live Photo later, the movie portion included the lens-switching actions that occurred after I pressed the shutter. That made me realize that I may be thinking about the capture lifecycle incorrectly. My questions are: When using AVCapturePhotoOutput with Live Photos enabled, what is the earliest point at which a capture can be considered “safely secured”? Is it expected that apps wait for PhotoKit import to complete before accepting another Live Photo capture request? If supporting rapid sequential shutter presses, is the recommended approach to queue capture requests and process them one at a time? Are there any best practices around lens changes or camera reconfiguration while a Live Photo is still being captured or processed? I’m not looking for details about the implementation of Apple’s Camera app. I’m mainly trying to understand the recommended approach when working with the public AVFoundation APIs. I’d appreciate any guidance, documentation references, or examples from developers who have worked through similar problems. Thanks!
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Activity
10h
Reference Mode custom presets do not reproduce the same grayscale response as built-in Apple presets
I found an issue with macOS Reference Modes where a recreated custom preset does not match the grayscale response of the original Apple-provided preset, even when all visible settings appear to be identical. For example, when duplicating the built-in Apple Display P3-600 nits Reference Mode preset, the duplicated preset does not produce the same grayscale luminance response as the original system preset. The comparison is performed under the same physical display brightness setting. The difference is not caused by different brightness levels. The native Reference Mode preset and the recreated preset are tested at the same display brightness, but the grayscale response is still different. The same behavior also occurs when manually creating a new Reference Mode preset with equivalent parameters, including using Pure Gamma settings. Even when the gamma value and other visible parameters are matched, the grayscale transfer function in the shadow region does not match the original Apple preset. The difference can be observed using grayscale test patterns, including: BarsAndBlack_16bit.TIFF CT ColorBar test pattern With these test images, the recreated preset shows lifted dark tones compared with the original Apple Display P3-600 nits preset. The darker grayscale steps become brighter, indicating that the EOTF/grayscale response is not identical between the built-in preset and the recreated preset. This behavior can be reproduced using the built-in macOS Preview application. Opening the same test image and switching between the native Reference Mode preset and the recreated preset shows differences in the black level and shadow grayscale response. The issue can be reproduced on both macOS 26.4 and macOS 15. Environment: macOS: 26.4 (also reproducible on macOS 15) Mac: 14-inch MacBook Pro Display: Built-in XDR Display Reference Mode tested: Apple Display P3-600 nits The main question is: When there is a difference between the built-in Apple Reference Mode preset and a recreated preset with the same visible parameters, which one represents the intended and accurate gamma/EOTF response? Specifically: Is the built-in Apple Display P3-600 nits Reference Mode using additional internal calibration data or hidden parameters that are not exposed in the Reference Mode configuration UI? Is the recreated preset actually applying the requested gamma curve correctly, while the Apple preset includes additional processing? Or is the Apple built-in preset the accurate reference implementation, and the recreated preset cannot reproduce it because some internal display calibration information is unavailable? Is there a documented way to create a custom Reference Mode preset that exactly matches the grayscale response of an Apple system preset? Thank you.
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19h
Technology
I want to know more about the latest technology from Apple and interesting hardware for me to know about.
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MusicKit with Music Understanding?
Is there some bridge we could use to have Music Understanding use a song via MusicKit. it would be great to be able to link a music score to a song in MusicKit, then use the features in music understanding to link a live playback with the score.
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PhotogrammetrySession(input: [PhotogrammetrySample]) Hangs or terminates
Providing a response and feedback to this: https://origin-devforums.apple.com/forums/thread/827311 and https://developer.apple.com/forums/thread/827043?page=1#889020022 I have a created a feedback/bug report with ID FB22823733 Feedback Report: I have created a feedback report as well like recommended with this ID: FB22823733, with more elaborate images of my implementation, also see here More clarity: Yes, this is for an iOS app(iOS 18+) but testing and debugging on Xcode(MacOS 15.7.7, M4 24GB), which traps or hangs on getting to [PhotogrammetrySample] even while using the lazy sequence and the contentsOf as specified in your docs. I also tried using the PhotogrammetrySession folder run but its still failed with : CoreOC.PhotogrammetrySession.Error 6 and I understand to mean alignment failed. What can be done or do you guys expose any functions that can be used to aid, or handle these internally, can't find any internally. The ObjectMasks are actually segmentation masks from an ML algorithm . To replicate try calling PhotogrammetrySession(input: [PhotogrammetrySample]) with contentsOf as captured on your documentation, even with like 30 image set or is there something I'm missing.
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1d
PHAssetResourceUploadJobChangeRequest doesn't upload iCloud-optimized photos — is this expected?
I'm implementing PHBackgroundResourceUploadExtension to back up photos and videos to our cloud storage service. During testing, I observed that iCloud-optimized photos (where the full-resolution original is stored in iCloud, not on device) do not upload. The upload job appears to silently skip these assets. Questions: Is this behavior intentional/documented? I couldn't find explicit mention of this limitation. If the device only has the optimized/thumbnail version locally, does the system: - Automatically download the full-resolution asset from iCloud before uploading? - Skip the asset entirely? - Return an error via PHAssetResourceUploadJobChangeRequest? For a complete backup solution, should we: - Pre-fetch full-resolution assets using PHAssetResourceManager.requestData(for:options:) before creating upload jobs? - Use a hybrid approach (this extension for local assets + separate logic for iCloud-only assets)? Environment: iOS 26, Xcode 18
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247
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2d
Restore certain photo resources
Through the Photos framework, we can access (and thus backup) resources the user created in Photos, such as Adjustments.plist, AdjustmentsSecondary.data, .aae files and more. Is there any way to restore those resources back into the Photos library? (e.g., similar to dropping a combination of .heic and .mov file to restore a Live Photo)
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List of RAW 9 bugs
Thanks for adding CoreML into the Apple RAW decoder. I'm excited with what it can bring. But I'm having a number of issues with it. My code base is written in Objective-C, and I'm using my custom MTKView. Now when I enabled RAW 9 support, the render is extremely slow (instant vs seconds). The UI would appear to hang with a spinning color wheel. It feels like CoreML processing is being delegated in the rendering thread, which runs on the main queue. How can I improve performance? As someone has reported, there is a black horizontal line in the middle of the image. The image that I was testing came from Fuji X-T5. If I enable EDR (Extended Dynamic Range), RAW 9 stops rendering, and will return ANE error. My app does HDR rendering of RAW files. I cannot get something like Sony A7R IV ARW image to load. Same ANE error. Is there a memory setting I need to tweak? When I render the X-T5 image, the colors appear to be overly saturated, which is different from the result of RAW 8. I cannot speak for the color rendering of other types of RAW files. I was told code base with Catalyst (and perhaps Swift) works without issue, other than being slow (except for large RAW files), but there seems to be an issue with Objective-C?
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2d
How to upload large videos with PHAssetResourceUploadJobChangeRequest?
I'm implementing a PHBackgroundResourceUploadExtension to back up photos and videos from the user's library to our cloud storage service. Our existing upload infrastructure uses chunked uploads for large files (splitting videos into smaller byte ranges and uploading each chunk separately). This approach: Allows resumable uploads if interrupted Stays within server-side request size limits Provides granular progress tracking Looking at the PHAssetResourceUploadJobChangeRequest.createJob(destination:resource:) API, I don't see a way to specify byte ranges or create multiple jobs for chunks of the same resource. Questions: Does the system handle large files (1GB+) automatically under the hood, or is there a recommended maximum file size for a single upload job? Is there a supported pattern for chunked/resumable uploads, or should the destination URL endpoint handle the entire file in one request? If our server requires chunked uploads (e.g., BITS protocol with CreateSession → Fragment → CloseSession), is this extension the right mechanism, or should we use a different approach for large videos? Any guidance on best practices for large asset uploads would be greatly appreciated. Environment: iOS 26, Xcode 18
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MusicKit.js / WKWebView: Are audible hitches during seek a known WebKit or Apple Media Stack limitation?
We are building a musician practice application that uses MusicKit.js inside a WKWebView on iOS and macOS. One of our core use cases is musical looping, where playback repeatedly seeks back to a loop start position while a song is playing. A typical loop length is 1-4 seconds, making interruptions that might be acceptable for general media playback very noticeable in our use case. For looping we currently use MusicKit’s seekToTime() API. We have also experimented with audioElement.fastSeek() and directly setting audioElement.currentTime. In all cases, seeking to a nearby position during playback produces an audible hitch or pause, even when the destination appears to already be buffered. We have observed similar interruptions when changing the playback rate during playback. For comparison, the same JavaScript bridge architecture running in a Chromium-based WebView on Android exhibits significantly smoother seek behavior and supports near-seamless looping. At this point, the WebView media stack appears to be the primary platform difference we have identified. We are currently using MusicKit.js v2. We are aware that v3 is available, but have not found anything suggesting this behavior has changed. As part of our investigation, we also experimented with Apple’s native MusicKit APIs. We observed that seeking and playback-rate changes can still produce audible interruptions, although playback-rate changes behave noticeably better than our MusicKit.js / HTML audio implementation. This led us to wonder whether the behavior originates from the underlying Apple media pipeline rather than MusicKit.js itself. Our questions are: Is it expected that seeking during playback, whether through seekToTime(), fastSeek(), or currentTime, causes the playback pipeline to be interrupted or rebuilt on Apple platforms? Are there known differences in WebKit’s media pipeline, buffering, or seek handling that would explain why the same implementation exhibits smoother seek behavior in a Chromium-based WebView? If so, are there recommended WebKit, WKWebView, or MusicKit.js techniques to achieve smoother, near-seamless looping? Given that we observe similar, though less pronounced, behavior when using native MusicKit APIs, is this a known characteristic or limitation of the underlying Apple media stack? If so, are there any APIs or implementation patterns recommended for applications that require tight musical looping and low-latency seeks? Any guidance would be greatly appreciated. Our goal is to provide musicians with seamless looping for practice and transcription, where even very small interruptions are noticeable.
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CIContext memoryLimit tips?
I would like to use the memory limit during interactive editing on iOS to decrease jetsam risk. However, I'm unsure of what to set it to. Do you have a recommendation as a fraction of physical memory? I have set the extended virtual memory entitlement, but I don't know what fraction of physical memory (or more) that entitlement enables - perhaps I should use a larger memory limit for M1-based iPads?
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List of RAW 9 bugs
Thanks for adding CoreML into the Apple RAW decoder. I'm excited with what it can bring. But I'm having a number of issues with it. My code base is written in Objective-C, and I'm using my custom MTKView. Now when I enabled RAW 9 support, the render is extremely slow (instant vs seconds). The UI would appear to hang with a spinning color wheel. It feels like CoreML processing is being delegated in the rendering thread, which runs on the main queue. How can I improve performance? As someone has reported, there is a black horizontal line in the middle of the image. The image that I was testing came from Fuji X-T5. If I enable EDR (Extended Dynamic Range), RAW 9 stops rendering, and will return ANE error. My app does HDR rendering of RAW files. I cannot get something like Sony A7R IV ARW image to load. Same ANE error. Is there a memory setting I need to tweak? When I render the X-T5 image, the colors appear to be overly saturated, which is different from the result of RAW 8. I cannot speak for the color rendering of other types of RAW files. I was told code base with Catalyst (and perhaps Swift) works without issue, other than being slow (except for large RAW files), but there seems to be an issue with Objective-C?
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Extended Dynamic Range support
My app currently supports display and editing of RAW files in HDR mode (Extended Dynamic Range). I came across 2 issues: In HDR mode, if I am using the default boostAmount = 1.0, then some of the highlight colors will shift. Like a clear blue sky becomes a light gray / light purple sky. I've to set boostAmount = 0.0 to avoid this problem. Is this a bug or is there a way to keep the Apple colors and not having this issue? The Shadow and highlight filter does not appear to work correctly in HDR mode, I've it hooked up in the linearSpaceFilter. Would be nice if you guys can introduce a spatial aware shadow & highlight filter.
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RAW 9 / RAW 9.dng
What is the difference (if any) between RAW 9 and RAW 9.DNG in terms of quality, noise reduction, and color?
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RAW 9: Color Differences between 9 and 8
Are color differences expected for any cameras? I have heard some reports, but have not seen it myself. If it's not expected, then I can get those people to file bugs.
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CIContext memoryTarget defaults and Extended Virtual Addressing on macOS
Is the memoryLimit option mentioned in WWDC26 session 305 the same option as CIContextOption.memoryTarget? The session says the default memory target on iOS is 256 MB. What is the default memoryTarget on macOS? Also, the session recommends the Extended Virtual Addressing entitlement for interactive RAW editing. That entitlement does not appear to be available for macOS, so does Core Image automatically use a larger intermediate cache budget on macOS? Should memoryTarget be used only for export contexts, or can/should it also be tuned for interactive editing contexts with cacheIntermediates enabled? Thanks!
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List of RAW 9 bugs
Thanks for adding CoreML into the Apple RAW decoder. I'm excited with what it can bring. But I'm having a number of issues with it. My code base is written in Objective-C, and I'm using my custom MTKView. Now when I enabled RAW 9 support, the render is extremely slow (instant vs seconds). The UI would appear to hang with a spinning color wheel. It feels like CoreML processing is being delegated in the rendering thread, which runs on the main queue. How can I improve performance? As someone has reported, there is a black horizontal line in the middle of the image. The image that I was testing came from Fuji X-T5. If I enable EDR (Extended Dynamic Range), RAW 9 stops rendering, and will return ANE error. My app does HDR rendering of RAW files. I cannot get something like Sony A7R IV ARW image to load. Same ANE error. Is there a memory setting I need to tweak? When I render the X-T5 image, the colors appear to be overly saturated, which is different from the result of RAW 8. I cannot speak for the color rendering of other types of RAW files. I was told code base with Catalyst (and perhaps Swift) works without issue, other than being slow (except for large RAW files), but there seems to be an issue with Objective-C?
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Interactive Performance Tips?
Aside from setting inputScaleFactor and using cacheIntermediates, what are the most important things to do to get great interactive performance with Core Image (both when constructing a CIImage from URL and using CIRAWFilter). Perhaps CIImage lifetimes or how they are mutated? Alternatively, what patterns (again other than inputScaleFactor / cacheIntermediates) most hurt performance?
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