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Video Q&A

Connect with Apple engineers in the Video Q&A on the Apple Developer Forums.

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Displaying a processed image from AVCaptureVideoDataOutput in a swiftUI view?
What is the recommended way of showing a processed image from AVCaptureVideoDataOutput in a swiftUI view? Currently my chain is AVCaptureVideoDataOutput(SampleBuffer) -> CIImage -> CIFilters -> createCGImage from processed CIImage -> Create swiftUI 'Image' from CGIImage, that is in a view Is there a better way to go from AVCaptureVideoDataOutput to a swiftUI view, with image processing?
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91
3h
How many concurrent VTCompressionSession / VTDecompressionSession can an app run, and can the limit be queried?
I'm batch-transcoding a library of clips into downscaled editing proxies. If I kick off two hardware transcodes at once, the encoder reliably falls over, so right now I run everything serially: each clip gets fully decoded, encoded, and muxed before the next one starts. It works, but it's slow, and the decode and encode hardware are mostly idle waiting on each other. A few things I can't pin down from the docs: Is there an actual ceiling on how many VTCompressionSession / VTDecompressionSession instances can be live at once, and does it depend on the device, the codec, or the resolution? Can I query that ceiling at runtime? I'd rather size my concurrency up front than find it by crashing. Decode and encode are separate hardware blocks, so can I safely run a decode session for one clip while the previous clip is still encoding, or does VideoToolbox serialize them anyway? When I do go over the limit, what should I be checking so I can back off cleanly? Right now I just get a crash instead of an error I can catch. Anything that gets me off the fully-serial pipeline would help. Thank you
3
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170
3h
Offscreen drawing to generate video content
We develop software for video broadcasting, including for sporting events, where animated scoreboards play a key role. macOS offers excellent features for such animations—such as CAAnimations—but this holds true only as long as the animations run on visible screens. Distributing the video signal (e.g., via NDI) requires access to the CVPixelBuffers of the individual frames. Currently, we generate the animations on an external screen and create the pixel buffers using ScreenCaptureKit. We are unaware of any way to obtain these pixel buffers without relying on such—strictly speaking, unnecessary—external screens (or multiple screens). If the window is created offscreen, it updates only once per second, which is unusable. Are there alternatives to external screens? If not, why can’t we create a virtual offscreen device for such use cases—one where we specify the required frame rate and rendering frequency—to generate the necessary video frames? This would also be helpful for HTML-based overlays, which are becoming increasingly popular; currently, these are also rendered only once per second when offscreen.
1
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133
4h
Automatic sign-in on tvOS
I have a streaming video app in the App Store. I would like to use the automatic sign in feature for tvOS that was introduced in WWDC '25. However, it requires the com.apple.developer.video-subscriber-single-sign-on entitlement. I'm told that I have to join the video partnership program to access that entitlement. I filled out the forms to join the partnership program, but was ghosted. Would you consider making this feature available to everyone, not just those in the video partnership program? It is frustrating that a new and useful feature isn't actually available.
0
0
53
4h
Displaying a processed image from AVCaptureVideoDataOutput in a swiftUI view?
What is the recommended way of showing a processed image from AVCaptureVideoDataOutput in a swiftUI view? Currently my chain is AVCaptureVideoDataOutput(SampleBuffer) -> CIImage -> CIFilters -> createCGImage from processed CIImage -> Create swiftUI 'Image' from CGIImage, that is in a view Is there a better way to go from AVCaptureVideoDataOutput to a swiftUI view, with image processing?
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2
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0
Views
91
Activity
3h
How many concurrent VTCompressionSession / VTDecompressionSession can an app run, and can the limit be queried?
I'm batch-transcoding a library of clips into downscaled editing proxies. If I kick off two hardware transcodes at once, the encoder reliably falls over, so right now I run everything serially: each clip gets fully decoded, encoded, and muxed before the next one starts. It works, but it's slow, and the decode and encode hardware are mostly idle waiting on each other. A few things I can't pin down from the docs: Is there an actual ceiling on how many VTCompressionSession / VTDecompressionSession instances can be live at once, and does it depend on the device, the codec, or the resolution? Can I query that ceiling at runtime? I'd rather size my concurrency up front than find it by crashing. Decode and encode are separate hardware blocks, so can I safely run a decode session for one clip while the previous clip is still encoding, or does VideoToolbox serialize them anyway? When I do go over the limit, what should I be checking so I can back off cleanly? Right now I just get a crash instead of an error I can catch. Anything that gets me off the fully-serial pipeline would help. Thank you
Replies
3
Boosts
0
Views
170
Activity
3h
Offscreen drawing to generate video content
We develop software for video broadcasting, including for sporting events, where animated scoreboards play a key role. macOS offers excellent features for such animations—such as CAAnimations—but this holds true only as long as the animations run on visible screens. Distributing the video signal (e.g., via NDI) requires access to the CVPixelBuffers of the individual frames. Currently, we generate the animations on an external screen and create the pixel buffers using ScreenCaptureKit. We are unaware of any way to obtain these pixel buffers without relying on such—strictly speaking, unnecessary—external screens (or multiple screens). If the window is created offscreen, it updates only once per second, which is unusable. Are there alternatives to external screens? If not, why can’t we create a virtual offscreen device for such use cases—one where we specify the required frame rate and rendering frequency—to generate the necessary video frames? This would also be helpful for HTML-based overlays, which are becoming increasingly popular; currently, these are also rendered only once per second when offscreen.
Replies
1
Boosts
0
Views
133
Activity
4h
Automatic sign-in on tvOS
I have a streaming video app in the App Store. I would like to use the automatic sign in feature for tvOS that was introduced in WWDC '25. However, it requires the com.apple.developer.video-subscriber-single-sign-on entitlement. I'm told that I have to join the video partnership program to access that entitlement. I filled out the forms to join the partnership program, but was ghosted. Would you consider making this feature available to everyone, not just those in the video partnership program? It is frustrating that a new and useful feature isn't actually available.
Replies
0
Boosts
0
Views
53
Activity
4h