60 fps 视频录制问题，即使它有能力 swift

Question

I am trying to record 60 fps video by modifying AVCAM application which can be found at:

https://github.com/Lax/Learn-iOS-Swift-by-Examples/tree/master/AVCam/Swift/AVCam

Hence, it is normally getting 2-30 fps with my phone (iPhone X) and I tried to change the format it captures video.

'''

    do {
        // Choose the back dual camera if available, otherwise default to a wide angle camera.
        if let dualCameraDevice = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .front) {
            defaultVideoDevice = dualCameraDevice
            do{
                if let formats = defaultVideoDevice?.formats {
                    for format in formats{
                        let formatDesc = format.formatDescription
                        print(format.videoSupportedFrameRateRanges)
                        let frameRate = format.videoSupportedFrameRateRanges.first
                        print(format.formatDescription)
                        if let frameRate = frameRate, frameRate.maxFrameRate == 60.0 {
                            try defaultVideoDevice?.lockForConfiguration()
                            print(frameRate.maxFrameRate) //here prints 60.0
                            defaultVideoDevice?.activeVideoMaxFrameDuration = CMTimeMake(1,60)
                            defaultVideoDevice?.activeVideoMinFrameDuration = CMTimeMake(1,60)
                            defaultVideoDevice?.unlockForConfiguration()
                        }
                    }
                }
            }

'''

Here at the line of 'defaultVideoDevice?.activeVideoMaxFrameDuration = CMTimeMake(1,60)' I am getting this error:

2019-11-21 09:23:50.225376+0300 AVCam[1250:667986] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[AVCaptureDevice setActiveVideoMaxFrameDuration:] Unsupported frame duration - use -activeFormat.videoSupportedFrameRateRanges to discover valid ranges'

Thanks in advance.

Answer 1

You should set a valid format to AVCaptureDevice .

You can do this

// get device what you like
let device = xxxxx

// list all default formats for this device
for format in device.formats {
    var founded = false

    // check what you want and pick a perfect format. 
    let formatDesc = format.formatDescription

    // mediaType / SubType
    let mediaType = format.mediaSubType
    // if your target is above(equal) iOS 13. use formatDesc.mediaSubType
    let mediaSubType = CMFormatDescriptionGetMediaSubType(formatDesc) 

    // dimensions
    // if your target is above(equal) iOS 13. use formatDesc.dimensions
    let dimensions = CMVideoFormatDescriptionGetDimensions(formatDesc) 

    // fps
    let ranges = format.videoSupportedFrameRateRanges.first
    for supportedFPSRange in ranges {
        if supportedFPSRange.maxFrameRate == 60 {
            founded = true
        }
    }

    // support Multi cam
    let isMultiCamSupported = format.isMultiCamSupported

    ....

    if founded {
        // Set activeFormat for device! Your capture device is up and loaded.
        do {
            try device.lockForConfiguration()
            device.activeFormat = format
            device.unlockForConfiguration()
        } catch {
            // catch some locking error
        }

        // Don't forget break the loop.:p
        break
    }
}

Or you can use filter