CODEWITHSUNDEEP
iphoneavfoundationframe-rateavcapturesessionapple-vision
Konstantin Kuchenmeister
Konstantin Kuchenmeister

Reputation: 23

iPhone capture session: Set custom frame-rate

I've set up a captureSession and am now trying to set the framerate to 60. I am using an iPhone 12 Pro Max.

I am trying to set the frame rate with:

videoDevice?.activeVideoMinFrameDuration = CMTimeMake(value: 1, timescale: 60)

However, printing my .activeFormat tells me my iPhone only supports 30 fps.

I need 60 fps to match the frame rate of my machine learning model.

Configuration:

I do not have any cameras in this enum that allow me more than 30 fps. I create the videoDevice object therefore with:

let videoDevice = AVCaptureDevice.default(.builtInWideAngleCamera,                                           
                                          for: .video,
                                          position: .back)

What am I doing wrong?

Thanks

Upvotes: 2

Views: 1984

Answers (4)

Kakhi Kiknadze
Kakhi Kiknadze

Reputation: 83

Solution marked as the answer seemed to be not working for me but after some time I found out I was setting the frame rate before adding the device as an input. Make sure you add the device first and then set the frame rate. Otherwise it would override it with a default settings and your frame rate will be ignored. It would also be ignored if you choose a new preset for the session.

Choosing a new preset for the capture session also resets this property to its default value.

Upvotes: 0

sukidhar darisi
sukidhar darisi

Reputation: 26

Though other answers provide the outline for the solution, what worked for me when I need the best resolution for the given frame rate is this. If you want to further limit certain frame resolutions, you can add a filter method to ensure a threshold on dimensions.

extension AVCaptureDevice {
    func set(frameRate: Double) {
        do { try lockForConfiguration()
            activeFormat = formats.sorted(by: { f1, f2 in
                 f1.formatDescription.dimensions.height > f2.formatDescription.dimensions.height && f1.formatDescription.dimensions.width > f2.formatDescription.dimensions.width
            }).first(where: { format in
                format.videoSupportedFrameRateRanges.contains { range in
                    range.maxFrameRate == frameRate
                }
            }) ?? activeFormat
            guard let range = activeFormat.videoSupportedFrameRateRanges.first,
                  range.minFrameRate...range.maxFrameRate ~= frameRate
            else {
                print("Requested FPS is not supported by the device's activeFormat !")
                return
            }
            activeVideoMinFrameDuration = CMTimeMake(value: 1, timescale: Int32(frameRate))
            activeVideoMaxFrameDuration = CMTimeMake(value: 1, timescale: Int32(frameRate))
            unlockForConfiguration()
        } catch {
            print("LockForConfiguration failed with error: \(error.localizedDescription)")
        }
    }
}

Upvotes: 0

Konstantin Kuchenmeister
Konstantin Kuchenmeister

Reputation: 23

Thanks, this answered my question!:)

For anyone still wondering below is the code that I used:

    // Instantiate the video device: wide angle camera, back position
    let videoDevice = AVCaptureDevice.default(.builtInWideAngleCamera,
                                              for: .video,
                                              position: .back)
    
    
    // Set the frame rate to 60, as expected by the model
    try! videoDevice?.lockForConfiguration()
    
    videoDevice?.activeFormat = (videoDevice?.formats[30])!
    videoDevice?.activeVideoMinFrameDuration = CMTimeMake(value: 1, timescale: 60)
    videoDevice?.activeVideoMaxFrameDuration = CMTimeMake(value: 1, timescale: 60)
    
    videoDevice?.unlockForConfiguration()

    // Debug only
    // print(videoDevice?.activeFormat)

However, make sure to add some error handling:D

Thanks, again.

Upvotes: 0

Gordon Childs
Gordon Childs

Reputation: 36159

videoDevice.activeFormat is only the current format. videoDevice.formats contains all the possible formats.

Mine reports many formats capable of 60fps, e.g.

<AVCaptureDeviceFormat: 0x28337d7c0 'vide'/'420f' 1280x 720, { 1- 60 fps}, HRSI:2112x1188, fov:70.291, binned, supports vis, max zoom:24.00 (upscales @1.50), AF System:1, ISO:33.0-3168.0, SS:0.000015-1.000000, supports wide color, supports multicam>
...

So pick the best format for you, then make that your activeFormat and set the desired frame durations like so:

try! videoDevice.lockForConfiguration()

videoDevice.activeFormat = my60FPSFormat
videoDevice.activeVideoMinFrameDuration = CMTime(value: 1, timescale: 60)
videoDevice.activeVideoMaxFrameDuration = CMTime(value: 1, timescale: 60)

videoDevice.unlockForConfiguration()

Upvotes: 0

Related Questions