AVCaptureDevice's exposureDuration and iso not honored by AVCapturePhotoOutput - ios

Problem: use AVCaptureDevice.setExposureModeCustom to set a fast "shutter speed" (exposureDuration) and high ISO, call AVCapturePhotoOutput to take a photo, see in the resulting image that the exposureDuration / ISO are not used (even though the live video feed shows that it is using the duration/ISO by brightening/darkening as expected)

Turns out that AVCapturePhotoSettings.isAutoStillImageStabilizationEnabled is to blame: by default this is true, and when true your exposure duration and ISO setting can be ignored / reset.
Solution is to set this to false when you're using a custom exposure setting, like this:
// self.customDuration is nil if we're on auto-exposure, non-nil if we are on manual exposure, ie. we called AVCaptureDevice.setExposureModeCustom
let photoSettings: AVCapturePhotoSettings
if self.photoOutput.availablePhotoCodecTypes.contains(.hevc), heicSupported {
photoSettings = AVCapturePhotoSettings(format:
[AVVideoCodecKey: AVVideoCodecType.hevc])
} else {
photoSettings = AVCapturePhotoSettings(format:
[AVVideoCodecKey: AVVideoCodecType.jpeg])
}
// auto still image stabilization destroys our settings for custom exposure (iso, duration), so turn it off if we have any
photoSettings.isAutoStillImageStabilizationEnabled = self.customDuration == nil ?
self.photoOutput.isStillImageStabilizationSupported : false

Related

swift AVCapturePhotoOutput capturePhoto hangs preview

Showing preview in 1080 x 1440; getting photo with max resolution (3024 x 4032) and quality on iPhone 8 Plus with code:
capturePhotoOutput?.capturePhoto(with: configurePhotoSettings(), delegate: self)
with photo settings:
private func configurePhotoSettings() -> AVCapturePhotoSettings {
let photoSettings = AVCapturePhotoSettings()
photoSettings.isHighResolutionPhotoEnabled = true
photoSettings.isAutoStillImageStabilizationEnabled = (capturePhotoOutput?.isStillImageStabilizationSupported)!
photoSettings.isAutoDualCameraFusionEnabled = (capturePhotoOutput?.isDualCameraFusionSupported)!
return photoSettings
}
Doing this one by one (like sequential shooting mode) and preview freezes each time for a short time even if I do nothing in didFinishProcessingPhoto.
Looking for solution to make capturing smooth, maybe in background thread, but currently I'm stuck..
The reason of preview hangs is feature called optical stabilization.
You just need to turn it off for smooth preview while capturing photo:
photoSettings.isAutoStillImageStabilizationEnabled = false

AVCapturePhotoOutput orientation cannot be changed on ios

I am using ios 11, swift 4 and capturing a picture with av foundation library. I have a custom preview as shown and mysettings are as suggested. The problem is when I capture and save the CMSample buffer, it is leftLandscape oriented. I tried to change CapturePhotoOutput orientation but it resist to change?(changing photoOutputConnection.videoOrientation changes nothing?)
if let photoOutputConnection = capturePhotoOutput.connection(with: AVMediaType.video) {
if(photoOutputConnection.isVideoOrientationSupported) {
print("video oryantasyonu = \(photoOutputConnection.videoOrientation)")
} else {
print("video oryantasyonu desteklenmiyor ?!")
}
}
Here is the preview (phono screen):
and here is the capture output taken from xcode debug quick view:
Here is session configuration :
self.capturePhotoOutput = AVCapturePhotoOutput()
capturePhotoOutput.isHighResolutionCaptureEnabled = true
// A Live Photo captures both a still image and a short movie centered on the moment of capture,
// which are presented together in user interfaces such as the Photos app.
capturePhotoOutput.isLivePhotoCaptureEnabled = capturePhotoOutput.isLivePhotoCaptureSupported
guard self.captureSession.canAddOutput(capturePhotoOutput) else { return }
// The sessionPreset property of the capture session defines the resolution and quality level of the video output.
// For most photo capture purposes, it is best set to AVCaptureSessionPresetPhoto to deliver high resolution photo quality output.
self.captureSession.sessionPreset = AVCaptureSession.Preset.photo
self.captureSession.addOutput(capturePhotoOutput)
self.captureSession.commitConfiguration()

Manually set exposure for iOS camera in Swift

I understand that the camera in iOS automatically adjusts exposure continuously when capturing video and photos.
Questions:
How can I turn off the camera's automatic exposure?
In Swift code, how can I set the exposure for the camera to "zero" so that exposure is completely neutral to the surroundings and not compensating for light?
You can set the exposure mode by setting the "AVCaptureExposureMode" property. Documentation here.
var exposureMode: AVCaptureDevice.ExposureMode { get set }
3 things you gotta take into consideration.
1) Check if the device actually supports this with "isExposureModeSupported"
2) You have to "lock for configuration" before adjusting the exposure. Documentation here.
3) The exposure is adjusted by setting an ISO and a duration. You can't just set it to "0"
ISO:
This property returns the sensor's sensitivity to light by means of a
gain value applied to the signal. Only exposure duration values
between minISO and maxISO are supported. Higher values will result in
noisier images. The property value can be read at any time, regardless
of exposure mode, but can only be set using the
setExposureModeCustom(duration:iso:completionHandler:) method.
If you need only min, current and max exposure values, then you can use the following:
Swift 5
import AVFoundation
enum Esposure {
case min, normal, max
func value(device: AVCaptureDevice) -> Float {
switch self {
case .min:
return device.activeFormat.minISO
case .normal:
return AVCaptureDevice.currentISO
case .max:
return device.activeFormat.maxISO
}
}
}
func set(exposure: Esposure) {
guard let device = AVCaptureDevice.default(for: AVMediaType.video) else { return }
if device.isExposureModeSupported(.custom) {
do{
try device.lockForConfiguration()
device.setExposureModeCustom(duration: AVCaptureDevice.currentExposureDuration, iso: exposure.value(device: device)) { (_) in
print("Done Esposure")
}
device.unlockForConfiguration()
}
catch{
print("ERROR: \(String(describing: error.localizedDescription))")
}
}
}

issue while taking photo wtth flash On using AVCapturePhotoOutput

I am working on camera app. i am using AVCapturePhotoOutput for ios 10.x device and AVCaptureStillImageOutput for below 10.x devices.
I am using below capture settings while capturing Photo
let settings = AVCapturePhotoSettings()
let previewPixelType = settings.availablePreviewPhotoPixelFormatTypes.first!
let previewFormat = [kCVPixelBufferPixelFormatTypeKey as String: previewPixelType,
kCVPixelBufferWidthKey as String: 1080,
kCVPixelBufferHeightKey as String: 1080,
]
settings.previewPhotoFormat = previewFormat
settings.isHighResolutionPhotoEnabled = true
settings.flashMode = .on
settings.isAutoStillImageStabilizationEnabled = true
self.captureOutputPhoto?.capturePhoto(with: settings, delegate: self)
when i am try to capture photo using above setting
captureOutput:didFinishProcessingPhotoSampleBuffer:previewPhotoSampleBuffer:resolvedSettings:bracketSettings:error
above delegate throws error first time. I am beginner for AVCapturePhotoSettings. the problem is occurs after every successful photo capture with flash mode.
From Apple documentation:
You may not enable image stabilization if the flash mode is
on
. (Enabling the flash takes priority over the
isAutoStillImageStabilizationEnabled
setting.)
Not sure, if it should throw error, but you can try to remove this string
settings.isAutoStillImageStabilizationEnabled = true
captureOutput:didFinishProcessingPhotoSampleBuffer:previewPhotoSampleBuffer:resolvedSettings:bracketSettings:error:, an Objective-C delegate method, whose Swift version is photoOutput(_:didFinishProcessingPhoto:previewPhoto:resolvedSettings:bracketSettings:error:), is deprecated.
Instead implement the Swift method photoOutput(_:didFinishProcessingPhoto:error:).
I'm using this method for handling the flash settings. AVCaptureDevice is basically the camera that you are using and the AVCaptureFlashMode is the flash mode you want to use.
func changeFlashSettings(device: AVCaptureDevice, mode: AVCaptureFlashMode) {
do {
try device.lockForConfiguration()
device.flashMode = mode
device.unlockForConfiguration()
} catch {
print("Change Flash Configuration Error: \(error)")
}
}
With this you can set the flash setting to on, off or auto. Hope this helps.

Knowing resolution of AVCaptureSession's session presets

I'm accessing the camera in iOS and using session presets as so:
captureSession.sessionPreset = AVCaptureSessionPresetMedium;
Pretty standard stuff. However, I'd like to know ahead of time the resolution of the video I'll be getting due to this preset (especially because depending on the device it'll be different). I know there are tables online you can look this up (such as here: http://cmgresearch.blogspot.com/2010/10/augmented-reality-on-iphone-with-ios40.html ). But I'd like to be able to get this programmatically so that I'm not just relying on magic numbers.
So, something like this (theoretically):
[captureSession resolutionForPreset:AVCaptureSessionPresetMedium];
which might return a CGSize of { width: 360, height: 480}. I have not been able to find any such API, so far I've had to resort to waiting to get my first captured image and querying it then (which for other reasons in my program flow is not good).
I am no AVFoundation pro, but I think the way to go is:
captureSession.sessionPreset = AVCaptureSessionPresetMedium;
AVCaptureInput *input = [captureSession.inputs objectAtIndex:0]; // maybe search the input in array
AVCaptureInputPort *port = [input.ports objectAtIndex:0];
CMFormatDescriptionRef formatDescription = port.formatDescription;
CMVideoDimensions dimensions = CMVideoFormatDescriptionGetDimensions(formatDescription);
I'm not sure about the last step and I didn't try it myself. Just found that in the documentation and think it should work.
Searching for CMVideoDimensions in Xcode you'll find the RosyWriter example project. Have a look at that code (I don't have time to do that now).
You can programmatically get the resolution from activeFormat before capture begins, though not before adding inputs and outputs: https://developer.apple.com/library/ios/documentation/AVFoundation/Reference/AVCaptureDevice_Class/index.html#//apple_ref/occ/instp/AVCaptureDevice/activeFormat
private func getCaptureResolution() -> CGSize {
// Define default resolution
var resolution = CGSize(width: 0, height: 0)
// Get cur video device
let curVideoDevice = useBackCamera ? backCameraDevice : frontCameraDevice
// Set if video portrait orientation
let portraitOrientation = orientation == .Portrait || orientation == .PortraitUpsideDown
// Get video dimensions
if let formatDescription = curVideoDevice?.activeFormat.formatDescription {
let dimensions = CMVideoFormatDescriptionGetDimensions(formatDescription)
resolution = CGSize(width: CGFloat(dimensions.width), height: CGFloat(dimensions.height))
if (portraitOrientation) {
resolution = CGSize(width: resolution.height, height: resolution.width)
}
}
// Return resolution
return resolution
}
FYI, I attach here an official reply from Apple.
This is a follow-up to Bug ID# 13201137.
Engineering has determined that this issue behaves as intended based on the following information:
There are several problems with the included code:
1) The AVCaptureSession has no inputs.
2) The AVCaptureSession has no outputs.
Without at least one input (added to the session using [AVCaptureSession addInput:]) and a compatible output (added using [AVCaptureSession addOutput:]), there will be no active connections, therefore, the session won't actually run in the input device. It doesn't need to -- there are no outputs to which to deliver any camera data.
3) The JAViewController class assumes that the video port's -formatDescription property will be non nil as soon as [AVCaptureSession startRunning] returns.
There is no guarantee that the format description will be updated with the new camera format as soon as startRunning returns. -startRunning starts up the camera and returns when it is completely up and running, but doesn't wait for video frames to be actively flowing through the capture pipeline, which is when the format description would be updated.
You're just querying too fast. If you waited a few milliseconds more, it would be there. But the right way to do this is to listen for the AVCaptureInputPortFormatDescriptionDidChangeNotification.
4) Your JAViewController class creates a PVCameraInfo object in retrieveCameraInfo: and asks it a question, then lets it fall out of scope, where it is released and dealloc'ed.
Therefore, the session doesn't have long enough to run to satisfy your dimensions request. You stop the camera too quickly.
We consider this issue closed. If you have any questions or concern regarding this issue, please update your report directly (http://bugreport.apple.com).
Thank you for taking the time to notify us of this issue.
Best Regards,
Developer Bug Reporting Team
Apple Worldwide Developer Relations
According to Apple, there's no API for that. It stinks, I've had the same problem.
May be you can provide a list of all posible preset resolutions for every iPhone model and check which device model the app is running on? - using something like this...
[[UIDevice currentDevice] platformType] // ex: UIDevice4GiPhone
[[UIDevice currentDevice] platformString] // ex: #"iPhone 4G"
However, you have to update the list for each newer device model. Hope this helps :)
if preset is .photo, the return size is for still photo size, not preview video size
if preset is not .photo, the return size is for video size, not for captured photo size.
if self.session.sessionPreset != .photo {
// return video size, not captured photo size
let format = videoDevice.activeFormat
let formatDescription = format.formatDescription
let dimensions = CMVideoFormatDescriptionGetDimensions(formatDescription)
} else {
// other way to get video size
}
Answer of #Christian Beer is a good way for specified preset.
My way is a good for active preset.
The best way to do what you want (get a known video or image format) is to set the format of the capture device.
First find the capture device you want to use:
if #available(iOS 10.0, *) {
captureDevice = defaultCamera()
} else {
let devices = AVCaptureDevice.devices()
// Loop through all the capture devices on this phone
for device in devices {
// Make sure this particular device supports video
if ((device as AnyObject).hasMediaType(AVMediaType.video)) {
// Finally check the position and confirm we've got the back camera
if((device as AnyObject).position == AVCaptureDevice.Position.back) {
captureDevice = device as AVCaptureDevice
}
}
}
}
self.autoLevelWindowCenter = ALCWindow.frame
if captureDevice != nil && currentUser != nil {
beginSession()
}
}
func defaultCamera() -> AVCaptureDevice? {
if #available(iOS 10.0, *) { // only use the wide angle camera never dual camera
if let device = AVCaptureDevice.default(AVCaptureDevice.DeviceType.builtInWideAngleCamera,
for: AVMediaType.video,
position: .back) {
return device
} else {
return nil
}
} else {
return nil
}
}
Then find the formats that that device can use:
let options = captureDevice!.formats
var supportable = options.first as! AVCaptureDevice.Format
for format in options {
let testFormat = format
let description = testFormat.description
if (description.contains("60 fps") && description.contains("1280x 720")){
supportable = testFormat
}
}
You can do more complex parsing of the formats, but you might not care.
Then just set the device to that format:
do {
try captureDevice?.lockForConfiguration()
captureDevice!.activeFormat = supportable
// setup other capture device stuff like autofocus, frame rate, ISO, shutter speed, etc.
try captureSession.addInput(AVCaptureDeviceInput(device: captureDevice!))
// add the device to an active CaptureSession
}
You may want to look at the AVFoundation docs and tutorial on AVCaptureSession as there are lots of things you can do with the output as well. For example, you can convert the result to .mp4 using AVAssetExportSession so that you can post it on YouTube, etc.
Hope this helps
Apple is using 4:3 ratio for the iPhone camera.
You can you this ratio to get the frame size of the captured video by fixing either the width or height constraint of the AVCaptureVideoPreviewLayer and set the aspect ratio constraint to 4:3.
In the left image, the width was fixed to 300px and the height was retrieved by setting the 4:3 ratio, and it was 400px.
In the right image, the height was fixed to 300px and width was retrieved by setting the 3:4 ratio, and it was 225px.

Resources