Device torch turns off when starting AVCaptureSession

Question

I'm using AVCaptureSession to capture video.

I want to light on the torch during the whole session, but once the session is started, the light turns automatically off.

这里有很多帖子展示了如何打开手电筒。它有效，除非捕获会话已启动。

这是我开始会话的方式

guard let camera = AVCaptureDevice.default(for: .video) else { return }
self.captureSession.beginConfiguration()

let deviceInput = try AVCaptureDeviceInput(device: camera)
self.captureSession.addInput(deviceInput)

let videoOutput = AVCaptureVideoDataOutput()
videoOutput.setSampleBufferDelegate(self, queue: DispatchQueue(label: "com.axelife.axcapturer.samplebufferdelegate"))
self.captureSession.addOutput(videoOutput)

try camera.setLight(on: true)
self.captureSession.commitConfiguration()

DispatchQueue(label: "capturesession").async {
    self.captureSession.startRunning()
}

还有我开灯的代码

extension AVCaptureDevice {
    func setLight(on: Bool) throws {
        try self.lockForConfiguration()
        if on {
            try self.setTorchModeOn(level: 1)
        }
        else {
            self.torchMode = .off
        }
        self.unlockForConfiguration()
    }
}

使用该代码，灯会在 < 0.5 秒内打开，然后自动关闭。

Answer 1

好的，我想通了。

手电筒必须在会议开始后点燃。

所以而不是：

try camera.setLight(on: true)
self.captureSession.commitConfiguration()

DispatchQueue(label: "capturesession").async {
    self.captureSession.startRunning()
}

做就是了

self.captureSession.commitConfiguration()

DispatchQueue(label: "capturesession").async {
    self.captureSession.startRunning()
    try camera.setLight(on: true)
}