I see some demo show convert HDR video to SDR Pixelbuffer,such AVAssetReader、 AVVideoComposition 、AVComposition 、AVFoundation.
But In some cases,I want to render HDR Pixelbuffer and record video.
AVCaptureSession *session = [[AVCaptureSession alloc] init];
session.sessionPreset = AVCaptureSessionPresetHigh;
AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if ([videoDevice isVideoHDRSupported]) {
NSError *error = nil;
if ([videoDevice lockForConfiguration:&error]) {
videoDevice.automaticallyAdjustsVideoHDREnabled = NO;
videoDevice.videoHDREnabled = YES; // 开启 HDR
[videoDevice unlockForConfiguration];
} else {
NSLog(@"Error: %@", error.localizedDescription);
}
}
Real-time processing of HDR data requires processing of video frame data (such as filters), ensuring that the processing chain supports 10-bit color depth and HDR metadata. And use imagesBuffer to object tracking, etc.
How to solve this problem?
Video
RSS for tagDive into the world of video on Apple platforms, exploring ways to integrate video functionalities within your iOS,iPadOS, macOS, tvOS, visionOS or watchOS app.
Selecting any option will automatically load the page
Post
Replies
Boosts
Views
Activity
I'm experiencing an unexpected behavior with AVURLAsset and cookies. When setting cookies through AVURLAssetHTTPCookiesKey option, they seem to be sent only on the initial request but not on retry attempts.
Here's my current implementation:
let cookieProperties: [HTTPCookiePropertyKey: Any] = [
.name: "sessionCookie",
.value: "testValue",
.domain: url.host ?? "",
.path: "/",
.secure: true
]
if let cookie = HTTPCookie(properties: cookieProperties) {
let asset = AVURLAsset(url: url, options: [
AVURLAssetHTTPCookiesKey: [cookie],
])
}
According to the documentation, AVURLAssetHTTPCookiesKey should apply the cookies to all requests made by this asset. However, when the initial request fails and AVPlayer retries, the cookies are not included in subsequent requests.
Only when I store the cookie with HTTPCookieStorage.shared.setCookie, then it persists.
Questions:
Is this the expected behavior?
If not, what could be causing the cookies to not persist for retry attempts?
Is using HTTPCookieStorage.shared the recommended approach instead?
Environment:
iOS 16+
Using AVPlayer with AVURLAsset
Streaming HLS content
Any insights would be greatly appreciated.
I’ve tried both AVCaptureVideoDataOutputSampleBufferDelegate (captureOutput) and AVCaptureDataOutputSynchronizerDelegate (dataOutputSynchronizer), but the number of depth frames and saved timestamps is significantly lower than the number of frames in the .mp4 file written by AVAssetWriter.
In my code, I save:
Timestamps for each frame to a metadata file
Depth frames to a binary file
Video to an .mp4 file
If I record a 4-second video at 30fps, the .mp4 file correctly plays for 4 seconds, but the number of stored timestamps and depth frames is much lower—around 70 frames instead of the expected 120.
Does anyone know why this mismatch happens?
func dataOutputSynchronizer(_ synchronizer: AVCaptureDataOutputSynchronizer,
didOutput synchronizedDataCollection: AVCaptureSynchronizedDataCollection) {
// Read all outputs
guard let syncedDepthData: AVCaptureSynchronizedDepthData =
synchronizedDataCollection.synchronizedData(for: depthDataOutput) as? AVCaptureSynchronizedDepthData,
let syncedVideoData: AVCaptureSynchronizedSampleBufferData =
synchronizedDataCollection.synchronizedData(for: videoDataOutput) as? AVCaptureSynchronizedSampleBufferData else {
// only work on synced pairs
return
}
if syncedDepthData.depthDataWasDropped || syncedVideoData.sampleBufferWasDropped {
return
}
let depthData = syncedDepthData.depthData
let depthPixelBuffer = depthData.depthDataMap
let sampleBuffer = syncedVideoData.sampleBuffer
guard let videoPixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer),
let formatDescription = CMSampleBufferGetFormatDescription(sampleBuffer) else {
return
}
addToPreviewStream?(CIImage(cvPixelBuffer: videoPixelBuffer))
if !canWrite() {
return
}
// Extract the presentation timestamp (PTS) from the sample buffer
let timestamp = CMSampleBufferGetPresentationTimeStamp(sampleBuffer)
//sessionAtSourceTime is the first buffer we will write to the file
if self.sessionAtSourceTime == nil {
//Make sure we don't start recording until the buffer reaches the correct time (buffer is always behind, this will fix the difference in time)
guard sampleBuffer.presentationTimeStamp >= self.recordFromTime! else { return }
self.sessionAtSourceTime = sampleBuffer.presentationTimeStamp
self.videoWriter!.startSession(atSourceTime: sampleBuffer.presentationTimeStamp)
}
if self.videoWriterInput!.isReadyForMoreMediaData {
self.videoWriterInput!.append(sampleBuffer)
self.videoTimestamps.append(
Timestamp(
frame: videoTimestamps.count,
value: timestamp.value,
timescale: timestamp.timescale
)
)
let ddm = depthData.depthDataMap
depthCapture.addDepthData(pixelBuffer: ddm, timestamp: timestamp)
}
}
Hi, I am a newbie here.
We have been given a task to build a robotic vision system to capture an immersive video in a hazed environment, which will later be played on Apple Vision Pro. I am thinking of starting with 2 or 4 basic CMOS camera sensors, such as IMX378, AR0144, or VD66GY, and designing an FPGA-based circuit to synchronously capture and store raw frame-by-frame data. Some frame initial processing such as demosaicing and filtering can also be done by the FPGA. Then, I would use software for post-processing to convert the data into a compatible video format for Apple Vision Pro.
Will this idea work? I can handle the raw data capture, but I’m unsure if this approach is feasible and what post-processing software I should use.
Thanks a lot for your suggestions!
Charlie
Topic:
Media Technologies
SubTopic:
Video
I’m currently working on a project where I capture both depth frames and RGB frames using AVCaptureDataOutputSynchronizer. Depth frames are stored as raw binary data and RGB frames are saved with AVAssetWriter.
The issue I’m facing is that AVAssetWriter enforces a fixed framerate, meaning it adds or discards frames to maintain that rate (as I understand it). This causes a desynchronization between the depth and RGB frames, which is a problem because I need each depth frame to be exactly matched with the corresponding RGB frame as they were captured.
How can I ensure that the RGB frames are saved without AVAssetWriter modifying the frame count?
I am creating an app that decodes H.265 elementary streams on iOS.
I use VideoToolBox to decode from H.265 to NV12.
The decoded data is enqueued in the CMSampleBufferDisplayLayer as a CMSampleBuffer.
However, nothing is displayed in the VideoPlayerView. It remains black.
The decoding in VideoToolBox is successful. I confirmed this by saving the NV12 data in the CMSampleBuffer to a file and displaying it using a tool.
Why is nothing displayed in the VideoPlayerView?
I can provide other source code as well.
//
// VideoPlayerView.swift
// H265Decoder
//
// Created by Kohshin Tokunaga on 2025/02/15.
//
import SwiftUI
import AVFoundation
struct VideoPlayerView: UIViewRepresentable {
// Return an H265Player as the coordinator, and start playback there.
func makeCoordinator() -> H265Player {
H265Player()
}
func makeUIView(context: Context) -> UIView {
let uiView = UIView(frame: .zero)
// Base layer for attaching sublayers
uiView.backgroundColor = .black // Screen background color (for iOS)
// Create the display layer and add it to uiView.layer
let displayLayer = context.coordinator.displayLayer
displayLayer.frame = uiView.bounds
displayLayer.backgroundColor = UIColor.clear.cgColor
uiView.layer.addSublayer(displayLayer)
// Start playback
context.coordinator.startPlayback()
return uiView
}
func updateUIView(_ uiView: UIView, context: Context) {
// Reset the frame of the AVSampleBufferDisplayLayer when the view's size changes.
let displayLayer = context.coordinator.displayLayer
displayLayer.frame = uiView.layer.bounds
// Optionally update the layer's background color, etc.
uiView.backgroundColor = .black
displayLayer.backgroundColor = UIColor.clear.cgColor
// Flush transactions if necessary
CATransaction.flush()
}
}
//
// H265Player.swift
// H265Decoder
//
// Created by Kohshin Tokunaga on 2025/02/15.
//
import Foundation
import AVFoundation
import CoreMedia
class H265Player: NSObject, VideoDecoderDelegate {
let displayLayer = AVSampleBufferDisplayLayer()
private var decoder: H265Decoder?
override init() {
super.init()
// Initial configuration for the display layer
displayLayer.videoGravity = .resizeAspect
// Initialize the decoder (delegate = self)
decoder = H265Decoder(delegate: self)
// For simple playback, set isBaseline to true
decoder?.isBaseline = true
}
func startPlayback() {
// Load the file "cars_320x240.h265"
guard let url = Bundle.main.url(forResource: "temp2", withExtension: "h265") else {
print("File not found")
return
}
do {
let data = try Data(contentsOf: url)
// Set FPS and video size as needed
let packet = VideoPacket(data: data,
type: .h265,
fps: 30,
videoSize: CGSize(width: 1080, height: 1920))
// Decode as a single packet
decoder?.decodeOnePacket(packet)
} catch {
print("Failed to load file: \(error)")
}
}
// MARK: - VideoDecoderDelegate
func decodeOutput(video: CMSampleBuffer) {
// When decoding is complete, send the output to AVSampleBufferDisplayLayer
displayLayer.enqueue(video)
}
func decodeOutput(error: DecodeError) {
print("Decoding error: \(error)")
}
}
Topic:
Media Technologies
SubTopic:
Video
Context
We develop an iOS/Apple TV app that allows to play HLS+FP Live streams (custom playback UI), some of which use the same FairPlay content key id. All FairPlay content keys are requested to the same content key server.
Implementation
Despite Apple documentation warning to not reuse AVContentKeySessions, we use only one AVContentKeySession for all channels which allows the system to reuse the content key when a content key id is met again. As seen in another thread, people seems to think this is OK.
Issue
When reusing the AVContentKeySession and the user quickly tunes channels multiple times (up to 2 or 3 times per second using gestures), an inconsistency may occur where the content key request for a previous streams is asked to the delegate after a new stream is already being prepared and its AVURLAsset already assigned as the content key session AVContentKeyRecipient. Note that the previous content key recipient is removed before the new one is added.
We also have been reported for crashes (though I haven't experienced it myself) when performing multiple channels tunings which makes us think that the AVContentKeySession should definitely not been reused.
Note: On the other hand if a new AVContentKeySession is used for each stream, the system systematically requests a content key even if previous streams have used the same content key id. In this case, neither the crash nor the inconsistency issue are observed but it dramatically increases the number of calls to the content key server.
Questions
Should AVContentKeySessions definitely not be reused? Otherwise, how to handle the inconsistency issue described above?
Hi,
I am recording video using my app. And setting up fps also using below code. But sometime video is being recorded using 20 FPS. Can someone please let me know what I am doing wrong?
private func eightBitVariantOfFormat() -> AVCaptureDevice.Format? {
let activeFormat = self.videoDeviceInput.device.activeFormat
let fpsToBeSupported: Int = 60
debugPrint("fpsToBeSupported - \(fpsToBeSupported)" as AnyObject)
let allSupportedFormats = self.videoDeviceInput.device.formats
debugPrint("all formats - \(allSupportedFormats)" as AnyObject)
let activeDimensions = CMVideoFormatDescriptionGetDimensions(activeFormat.formatDescription)
debugPrint("activeDimensions - \(activeDimensions)" as AnyObject)
let filterBasedOnDimensions = allSupportedFormats.filter({ (CMVideoFormatDescriptionGetDimensions($0.formatDescription).width == activeDimensions.width) && (CMVideoFormatDescriptionGetDimensions($0.formatDescription).height == activeDimensions.height) })
if filterBasedOnDimensions.isEmpty {
// Dimension not found. Required format not found to handle.
debugPrint("Dimension not found" as AnyObject)
return activeFormat
}
debugPrint("filterBasedOnDimensions - \(filterBasedOnDimensions)" as AnyObject)
let filterBasedOnMaxFrameRate = filterBasedOnDimensions.compactMap({ format in
let videoSupportedFrameRateRanges = format.videoSupportedFrameRateRanges
if !videoSupportedFrameRateRanges.isEmpty {
let contains = videoSupportedFrameRateRanges.contains(where: { Int($0.maxFrameRate) >= fpsToBeSupported })
if contains {
return format
} else {
return nil
}
} else {
return nil
}
})
debugPrint("allFormatsToBeSupported - \(filterBasedOnMaxFrameRate)" as AnyObject)
guard !filterBasedOnMaxFrameRate.isEmpty else {
debugPrint("Taking default active format as nothing found when filtered using desired FPS" as AnyObject)
return activeFormat
}
var formatToBeUsed: AVCaptureDevice.Format!
if let four_two_zero_v = filterBasedOnMaxFrameRate.first(where: { CMFormatDescriptionGetMediaSubType($0.formatDescription) == kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange}) {
// 'vide'/'420v'
formatToBeUsed = four_two_zero_v
} else {
// Take the first one from above array.
formatToBeUsed = filterBasedOnMaxFrameRate.first
}
do {
try self.videoDeviceInput.device.lockForConfiguration()
self.videoDeviceInput.device.activeFormat = formatToBeUsed
self.videoDeviceInput.device.activeVideoMinFrameDuration = CMTimeMake(value: 1, timescale: Int32(fpsToBeSupported))
self.videoDeviceInput.device.activeVideoMaxFrameDuration = CMTimeMake(value: 1, timescale: Int32(fpsToBeSupported))
if videoDeviceInput.device.isFocusModeSupported(.continuousAutoFocus) {
self.videoDeviceInput.device.focusMode = AVCaptureDevice.FocusMode.continuousAutoFocus
}
self.videoDeviceInput.device.unlockForConfiguration()
} catch let error {
debugPrint("\(error)" as AnyObject)
}
return formatToBeUsed
}
Hi,
I am recording a video at 240 FPS within my application and saving it to the Photos app. The recorded video retains 240 FPS in the Photos app. However, after trimming the video using the Photos app and importing it back into my app, the FPS is reduced to 30 FPS.
Steps to Reproduce:
Record a video inside the application at 240 FPS.
Save the recorded video to the Photos app.
Verify that the video retains 240 FPS in the Photos app.
Trim the video using the built-in Photos app editor.
Import the trimmed video back into the application.
The FPS of the imported video is now reduced to 30 FPS.
Code Used for Importing Video:
I am using the following code to fetch the video from the Photos app:
let options: PHVideoRequestOptions = PHVideoRequestOptions()
options.version = .current // Using `.original` preserves FPS, but I need `.current` for other changes
options.deliveryMode = .highQualityFormat
options.isNetworkAccessAllowed = true
PHImageManager.default().requestAVAsset(forVideo: self, options: options) { (avAsset, audioMix, info) in
if let urlAsset = avAsset as? AVURLAsset {
completionHandler(urlAsset.url, self)
} else {
self.askForOriginal(completionHandler: completionHandler)
}
}
Observations:
The original video retains 240 FPS until it is trimmed in the Photos app.
After trimming, the FPS automatically drops to 30 FPS when imported back into the app.
If I use options.version = .original, the FPS is preserved, but I need .current to apply other modifications.
Questions:
Is this an expected behavior of PHImageManager when requesting a video with options.version = .current?
Is there a way to preserve the original FPS while still using .current?
Are there any workarounds to extract the trimmed video without FPS reduction?
Any insights or solutions would be greatly appreciated. Thanks in advance!
No video is playing and the same error is coming. I have tried everything by resetting. Please get an update as soon as possible.
error-The operation couldn't be completed. (CoreMediaErrorDomain error -42709.)
When we use AVPlayer to play DRM encrypted streams, it will not play normally under iOS 17.6.1 system version, and there is a high probability of system restart. This is the relevant core error log:
error 14:47:53.323369+0800 audiomxd [AirPlayError] carManager_copyProperty_block_invoke:499: got error -12784/0xFFFFCE10 kCMBaseObjectError_PropertyNotFound
error 14:47:53.323414+0800 audiomxd [SPEndpointManagerFactory] SidePlay Endpoint Manager creation failed with -72390/0xFFFEE53A
error 14:47:53.364949+0800 audiomxd [APBrowserCarSessionHelper] [0xF6AA] [Bonjour/WiFi] Unrecognized ConnectivityHelper event 101
error 14:47:53.375313+0800 audiomxd AddInstanceForFactory: No factory registered for id <CFUUID 0xa5c5118c0> F8BB1C28-BAE8-11D6-9C31-00039315CD46
We're experiencing significant issues with AVPlayer when attempting to play partially downloaded HLS content in offline mode. Our app downloads HLS video content for offline viewing, but users encounter the following problems:
Excessive Loading Delay: When offline, AVPlayer attempts to load resources for up to 60 seconds before playing the locally available segments
Asset Loss: Sometimes AVPlayer completely loses the asset reference and fails to play the video on subsequent attempts
Inconsistent Behavior: The same partially downloaded asset might play immediately in one session but take 30+ seconds in another
Network Activity Despite Offline Settings: Despite configuring options to prevent network usage, AVPlayer still appears to be attempting network connections
These issues severely impact our offline user experience, especially for users with intermittent connectivity.
Technical Details
Implementation Context
Our app downloads HLS videos for offline viewing using AVAssetDownloadTask. We store the downloaded content locally and maintain a dictionary mapping of file identifiers to local paths. When attempting to play these videos offline, we experience the described issues.
Current Implementation
Here's our current implementation for playing the videos:
- (void)presentNativeAvplayerForVideo:(Video *)video navContext:(NavContext *)context {
NSString *localPath = video.localHlsPath;
if (localPath) {
NSURL *videoURL = [NSURL URLWithString:localPath];
NSDictionary *options = @{
AVURLAssetPreferPreciseDurationAndTimingKey: @YES,
AVURLAssetAllowsCellularAccessKey: @NO,
AVURLAssetAllowsExpensiveNetworkAccessKey: @NO,
AVURLAssetAllowsConstrainedNetworkAccessKey: @NO
};
AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:videoURL options:options];
AVPlayerViewController *playerViewController = [[AVPlayerViewController alloc] init];
NSArray *keys = @[@"duration", @"tracks"];
[asset loadValuesAsynchronouslyForKeys:keys completionHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:asset];
AVPlayer *player = [AVPlayer playerWithPlayerItem:playerItem];
playerViewController.player = player;
[player play];
});
}];
playerViewController.modalPresentationStyle = UIModalPresentationFullScreen;
[context presentViewController:playerViewController animated:YES completion:nil];
}
}
Attempted Solutions
We've tried several approaches to mitigate these issues:
Modified Asset Options:
NSDictionary *options = @{
AVURLAssetPreferPreciseDurationAndTimingKey: @NO, // Changed to NO
AVURLAssetAllowsCellularAccessKey: @NO,
AVURLAssetAllowsExpensiveNetworkAccessKey: @NO,
AVURLAssetAllowsConstrainedNetworkAccessKey: @NO,
AVAssetReferenceRestrictionsKey: @(AVAssetReferenceRestrictionForbidRemoteReferenceToLocal)
};
Skipped Asynchronous Key Loading:
AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:asset automaticallyLoadedAssetKeys:nil];
Modified Player Settings:
player.automaticallyWaitsToMinimizeStalling = NO;
[playerItem setPreferredForwardBufferDuration:2.0];
Added Network Resource Restrictions:
playerItem.canUseNetworkResourcesForLiveStreamingWhilePaused = NO;
Used File URLs Instead of HTTP URLs where possible
Despite these attempts, the issues persist.
Expected vs. Actual Behavior
Expected Behavior:
AVPlayer should immediately begin playback of locally available HLS segments
When offline, it should not attempt to load from network for more than a few seconds
Once an asset is successfully played, it should be reliably available for future playback
Actual Behavior:
AVPlayer waits 10-60 seconds before playing locally available segments
Network activity is observed despite all network-restricting options
Sometimes the player fails completely to play a previously available asset
Behavior is inconsistent between playback attempts with the same asset
Questions:
What is the recommended approach for playing partially downloaded HLS content offline with minimal delay?
Is there a way to force AVPlayer to immediately use available local segments without attempting to load from the network?
Are there any known issues with AVPlayer losing references to locally stored HLS assets?
What diagnostic steps would you recommend to track down the specific cause of these delays?
Does AVFoundation have specific timeouts for offline HLS playback that could be configured?
Any guidance would be greatly appreciated as this issue is significantly impacting our user experience.
Device Information
iOS Versions Tested: 14.5 - 18.1
Device Models: iPhone 12, iPhone 13, iPhone 14, iPhone 15
Xcode Version: 15.3-16.2.1
I am trying to achieve an animated gradient effect that changes values over time based on the current seconds. I am also using AVPlayer and AVMutableVideoComposition along with custom instruction and class to generate the effect. I didn't want to load any video file, but rather generate a custom video with my own set of instructions. I used Metal Compute shaders to generate the effects and make the video to be 20 seconds.
However, when I run the code, I get a frozen player with the gradient applied, but when I try to play the video, I get this warning in the console :- Visual isTranslatable: NO; reason: observation failure: noObservations
Here is the screenshot :-
My entire code :-
import AVFoundation
import Metal
class GradientVideoCompositorTest: NSObject, AVVideoCompositing {
var sourcePixelBufferAttributes: [String: Any]? = [
kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA
]
var requiredPixelBufferAttributesForRenderContext: [String: Any] = [
kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA
]
private var renderContext: AVVideoCompositionRenderContext?
private var metalDevice: MTLDevice!
private var metalCommandQueue: MTLCommandQueue!
private var metalLibrary: MTLLibrary!
private var metalPipeline: MTLComputePipelineState!
override init() {
super.init()
setupMetal()
}
func setupMetal() {
guard let device = MTLCreateSystemDefaultDevice(),
let queue = device.makeCommandQueue(),
let library = try? device.makeDefaultLibrary(),
let function = library.makeFunction(name: "gradientShader") else {
fatalError("Metal setup failed")
}
self.metalDevice = device
self.metalCommandQueue = queue
self.metalLibrary = library
self.metalPipeline = try? device.makeComputePipelineState(function: function)
}
func renderContextChanged(_ newRenderContext: AVVideoCompositionRenderContext) {
renderContext = newRenderContext
}
func startRequest(_ request: AVAsynchronousVideoCompositionRequest) {
guard let outputPixelBuffer = renderContext?.newPixelBuffer(),
let metalTexture = createMetalTexture(from: outputPixelBuffer) else {
request.finish(with: NSError(domain: "com.example.gradient", code: -1, userInfo: nil))
return
}
var time = Float(request.compositionTime.seconds)
renderGradient(to: metalTexture, time: time)
request.finish(withComposedVideoFrame: outputPixelBuffer)
}
private func createMetalTexture(from pixelBuffer: CVPixelBuffer) -> MTLTexture? {
var texture: MTLTexture?
let width = CVPixelBufferGetWidth(pixelBuffer)
let height = CVPixelBufferGetHeight(pixelBuffer)
let textureDescriptor = MTLTextureDescriptor.texture2DDescriptor(
pixelFormat: .bgra8Unorm,
width: width,
height: height,
mipmapped: false
)
textureDescriptor.usage = [.shaderWrite, .shaderRead]
CVPixelBufferLockBaseAddress(pixelBuffer, .readOnly)
if let textureCache = createTextureCache(), let cvTexture = createCVMetalTexture(from: pixelBuffer, cache: textureCache) {
texture = CVMetalTextureGetTexture(cvTexture)
}
CVPixelBufferUnlockBaseAddress(pixelBuffer, .readOnly)
return texture
}
private func renderGradient(to texture: MTLTexture, time: Float) {
guard let commandBuffer = metalCommandQueue.makeCommandBuffer(),
let commandEncoder = commandBuffer.makeComputeCommandEncoder() else { return }
commandEncoder.setComputePipelineState(metalPipeline)
commandEncoder.setTexture(texture, index: 0)
var mutableTime = time
commandEncoder.setBytes(&mutableTime, length: MemoryLayout<Float>.size, index: 0)
let threadsPerGroup = MTLSize(width: 16, height: 16, depth: 1)
let threadGroups = MTLSize(
width: (texture.width + 15) / 16,
height: (texture.height + 15) / 16,
depth: 1
)
commandEncoder.dispatchThreadgroups(threadGroups, threadsPerThreadgroup: threadsPerGroup)
commandEncoder.endEncoding()
commandBuffer.commit()
}
private func createTextureCache() -> CVMetalTextureCache? {
var cache: CVMetalTextureCache?
CVMetalTextureCacheCreate(kCFAllocatorDefault, nil, metalDevice, nil, &cache)
return cache
}
private func createCVMetalTexture(from pixelBuffer: CVPixelBuffer, cache: CVMetalTextureCache) -> CVMetalTexture? {
var cvTexture: CVMetalTexture?
let width = CVPixelBufferGetWidth(pixelBuffer)
let height = CVPixelBufferGetHeight(pixelBuffer)
CVMetalTextureCacheCreateTextureFromImage(
kCFAllocatorDefault,
cache,
pixelBuffer,
nil,
.bgra8Unorm,
width,
height,
0,
&cvTexture
)
return cvTexture
}
}
class GradientCompositionInstructionTest: NSObject, AVVideoCompositionInstructionProtocol {
var timeRange: CMTimeRange
var enablePostProcessing: Bool = true
var containsTweening: Bool = true
var requiredSourceTrackIDs: [NSValue]? = nil
var passthroughTrackID: CMPersistentTrackID = kCMPersistentTrackID_Invalid
init(timeRange: CMTimeRange) {
self.timeRange = timeRange
}
}
func createGradientVideoComposition(duration: CMTime, size: CGSize) -> AVMutableVideoComposition {
let composition = AVMutableComposition()
let instruction = GradientCompositionInstructionTest(timeRange: CMTimeRange(start: .zero, duration: duration))
let videoComposition = AVMutableVideoComposition()
videoComposition.customVideoCompositorClass = GradientVideoCompositorTest.self
videoComposition.renderSize = size
videoComposition.frameDuration = CMTime(value: 1, timescale: 30) // 30 FPS
videoComposition.instructions = [instruction]
return videoComposition
}
#include <metal_stdlib>
using namespace metal;
kernel void gradientShader(texture2d<float, access::write> output [[texture(0)]],
constant float &time [[buffer(0)]],
uint2 id [[thread_position_in_grid]]) {
float2 uv = float2(id) / float2(output.get_width(), output.get_height());
// Animated colors based on time
float3 color1 = float3(sin(time) * 0.8 + 0.1, 0.6, 1.0);
float3 color2 = float3(0.12, 0.99, cos(time) * 0.9 + 0.3);
// Linear interpolation for gradient
float3 gradientColor = mix(color1, color2, uv.y);
output.write(float4(gradientColor, 1.0), id);
}
Hello,
Is there a way to handle 403 error returned by the server, eg token expired ?
Cannot find any information about this and everything that I tried wasn't working (addObserver, NotificationCenter with .AVPlayerItemNewErrorLogEntry, AVPlayerItemPlaybackStalled, ...)
Thank you very much.
Topic:
Media Technologies
SubTopic:
Video
Are serialized parameters already available inside -pluginInstanceAddedToDocument via FxParameterRetrievalAPI or are they being read later?
I have an app that has a WKWebView for watching YouTube videos. When the videos are windowed the audio seems fine, positionally as well. All perfectly.
When I fullscreen the video and it goes into the native visionOS video player the audio messes up.
It will suddenly sound like it is in your ears, or maybe even just one ear channel, or the position will be wrong. It might be fine for a moment but the second I touch the controls or move the window the sound jumps across the room, away from the window, or switches to stereo.
Sometimes exiting windows entirely you will still hear the videos playing. Even if you open the window back up and go to another screen and open another video, now you hear 2 videos playing at the same time with no way to stop the first one in the background, requiring to force restart the app.
It is all sorts of glitchy. I haven't the slightest clue what is happening here. I am strongly feeling this is a visionOS bug.
I tried using AVAudioSession to change some of the sound settings, and that makes zero difference in behavior.
Multiple testers have also reported this behavior and it has been seen on both visionOS 2.3 and 2.4 betas.
Thanks for the help! This is driving me mad! It is extremely consistent behavior!
I am working on a project for macOS where I am taking an AVCaptureSession's CVPixelBuffer and I need to convert it into a MTLTexture for rendering. On macOS the pixel format is 2vuy, there does not seem to be a clear format conversion while converting to a metal texture. I have been able to convert it to a texture but the color space seems to be off as it is rendering distorted colors with a double image.
I believe 2vuy is a single pane color space and I have tried to account for that, but I am unaware of what is off.
I have attached The CVPixelBuffer and The distorted MTLTexture along with a laundry list of errors.
On iOS my conversions are fine, it is only the macOS 2vuy pixel format that seems to have issues.
My code for the conversion is also attached.
If there are any suggestions or guidance on how to properly convert a 2vuy CVPixelBuffer to a MTLTexture I would greatly appreciate it.
Many Thanks
Conversion_Logs.txt
ConversionCode.swift
When I play an m3u8 video using AVPlayer, it can play smoothly at 2x speed. However, when I set it to 3x speed, the playback is not smooth and there is no sound.
Topic:
Media Technologies
SubTopic:
Video
Short summary
When setting exposureMode to .locked or .custom the brightness of a video stream still changes depending on the composition and contrast of the visible scene. These changes seem to come from contrast enhancements or dynamic range optimizations and totally break any analysis of the image that requires to assess absolute luminance. While exposure lock seems to indeed lock the physical exposure parameters of the camera (shutter speed and ISO), I cannot find any way to control these "soft" modifiers.
Details
Background
I am the developer of the app "phyphox", an educational app that makes the phone's sensors accessible to students as measurement tools in science experiments. Currently I am working on implementing photometric measurements through the camera and one very important aspect of it is luminance measurements.
This is particularly relevant since the light sensor of the phone has no publicly accessible API and the camera could to some extend make experiments available to Apple users that are otherwise only possible on Android devices.
Implementation
The app uses AVFoundation and explicitly picks individual cameras since camera groups do not support custom exposure settings. This means that it handles camera switching during zoom by itself and even implements its own auto exposure routines to optimize for the use in experiments. Therefore it always stays in custom exposure mode. The app uses YUV420 color space and the individual frames are analyzed in Metal using compute shaders.
However, the effects discussed here still occur if I remove all code to control the camera and replace it with a simple sequence of setting the exposure mode to custom, setting custom exposure values, setting a fixed white balance and then setting the exposure mode to locked as suggested on stackoverflow. This neither helps on an iPhone 14 Pro nor on an iPhone 8 despite a report on the developer forums that it would resolve the issue for older devices.
The app is open source, so the code can be seen in our current development branch (without the changes for the tests here, though) on github.
The videos below use the implementation with the suggestion from stackoverflow, but they can be reproduced in the same way with "professional" camera apps that promise manual control over the camera (like the Blackmagic cam to quote a reputable company) as well as the stock camera app after pressing and holding on the preview to enable AE/AF lock.
Demonstration
These examples were captured on an iPhone 14 Pro. The central part of the image (highlighted by the app using metal shaders after capture) should not change with fixed exposure settings, but significant changes are noticable if there are changes at the edge of the frame when I move a black piece of cardboard in from above:
https://share.icloud.com/photos/0b1f_3IB6yAQG-qSH27pm6oDQ
The graph above the camera preview is the average luminance (gamma corrected and weighted based on sRGB) across the highlighted central area and as mentioned before it should not change because of something happening at the side of the frame (worst case it should get a bit darker because of the cardboard's shadow).
In my opinion, the iPhone changes its mind on the ideal contrast as soon as it has a different exposure histogram because of the dark image part from the cardboard, but that's just me guessing.
For completeness here is the same effect in the stock camera app with AE/AF lock enabled:
https://share.icloud.com/photos/0cd7QM8ucBZKwPwE9mybnEowg
Here you can also see that the iPhone "ramps" the changes. The brightness of the gray area does not change immediately but transitions smoothly, so this is clearly deliberate postprocessing.
So...
Any suggestion on how to prevent this behavior would be highly appreciated.
As of iOS 18, as far as I can tell, it appears there's still no AVPlayer options that allow users to toggle the caption / subtitle track on and off. Does anyone know of a way to do this with AVPlayer or with SwiftUI's VideoPlayer?
The following code reproduces this issue. It can be pasted into an app playground. This is a random video and a random vtt file I found on the internet.
import SwiftUI
import AVKit
import UIKit
struct ContentView: View {
private let video = URL(string: "https://server15700.contentdm.oclc.org/dmwebservices/index.php?q=dmGetStreamingFile/p15700coll2/15.mp4/byte/json")!
private let captions = URL(string: "https://gist.githubusercontent.com/samdutton/ca37f3adaf4e23679957b8083e061177/raw/e19399fbccbc069a2af4266e5120ae6bad62699a/sample.vtt")!
@State private var player: AVPlayer?
var body: some View {
VStack {
VideoPlayerView(player: player)
.frame(maxWidth: .infinity, maxHeight: 200)
}
.task {
// Captions won't work for some reason
player = try? await loadPlayer(video: video, captions: captions)
}
}
}
private struct VideoPlayerView: UIViewControllerRepresentable {
let player: AVPlayer?
func makeUIViewController(context: Context) -> AVPlayerViewController {
let controller = AVPlayerViewController()
controller.player = player
controller.modalPresentationStyle = .overFullScreen
return controller
}
func updateUIViewController(_ uiViewController: AVPlayerViewController, context: Context) {
uiViewController.player = player
}
}
private func loadPlayer(video: URL, captions: URL?) async throws -> AVPlayer {
let videoAsset = AVURLAsset(url: video)
let videoPlusSubtitles = AVMutableComposition()
try await videoPlusSubtitles.add(videoAsset, withMediaType: .video)
try await videoPlusSubtitles.add(videoAsset, withMediaType: .audio)
if let captions {
let captionAsset = AVURLAsset(url: captions)
// Must add as .text. .closedCaption and .subtitle don't work?
try await videoPlusSubtitles.add(captionAsset, withMediaType: .text)
}
return await AVPlayer(playerItem: AVPlayerItem(asset: videoPlusSubtitles))
}
private extension AVMutableComposition {
func add(_ asset: AVAsset, withMediaType mediaType: AVMediaType) async throws {
let duration = try await asset.load(.duration)
try await asset.loadTracks(withMediaType: mediaType).first.map { track in
let newTrack = self.addMutableTrack(withMediaType: mediaType, preferredTrackID: kCMPersistentTrackID_Invalid)
let range = CMTimeRangeMake(start: .zero, duration: duration)
try newTrack?.insertTimeRange(range, of: track, at: .zero)
}
}
}