Android 10 (api 29) camera2 api 回归与广角相机

Question

我在专为 Google Pixel 3 XL 设计的相机应用中使用了 camera2 api。该设备有两个前置摄像头（广角和普通）。多亏了多摄像头功能，我可以同时访问两个物理摄像头设备，我的应用程序具有在这两个摄像头之间切换的功能。在我最近升级到 Android 10 之前，我可以准确地看到两个不同的结果，但现在我的广角捕捉帧与普通相机具有几乎相同的 FOV（视野）。因此，Android 9 广角捕获结果上的相同代码、相同 apk 是宽的，正如预期的那样，并且在 Andoird 10 升级之后 - 广角和普通相机显示几乎相同的 FOV。

这是一个代码片段，用于演示我如何初始化两个摄像头并捕获预览：

主活动.kt

 private val surfaceReadyCallback = object: SurfaceHolder.Callback {
        override fun surfaceChanged(p0: SurfaceHolder?, p1: Int, p2: Int, p3: Int) { }
        override fun surfaceDestroyed(p0: SurfaceHolder?) { }

        override fun surfaceCreated(p0: SurfaceHolder?) {

            // Get the two output targets from the activity / fragment
            val surface1 = surfaceView1.holder.surface  
            val surface2 = surfaceView2.holder.surface 

            val dualCamera = findShortLongCameraPair(cameraManager)!!
            val outputTargets = DualCameraOutputs(
                null, mutableListOf(surface1), mutableListOf(surface2))

            //Open the logical camera, configure the outputs and create a session
            createDualCameraSession(cameraManager, dualCamera, targets = outputTargets) { session ->

                val requestTemplate = CameraDevice.TEMPLATE_PREVIEW
                val captureRequest = session.device.createCaptureRequest(requestTemplate).apply {
                    arrayOf(surface1, surface2).forEach { addTarget(it) }
                }.build()

                session.setRepeatingRequest(captureRequest, null, null)
            }
        }
    }


    fun openDualCamera(cameraManager: CameraManager,
                       dualCamera: DualCamera,
                       executor: Executor = SERIAL_EXECUTOR,
                       callback: (CameraDevice) -> Unit) {

        cameraManager.openCamera(
            dualCamera.logicalId, executor, object : CameraDevice.StateCallback() {
                override fun onOpened(device: CameraDevice) { callback(device) }

                override fun onError(device: CameraDevice, error: Int) = onDisconnected(device)
                override fun onDisconnected(device: CameraDevice) = device.close()
            })
    }

    fun createDualCameraSession(cameraManager: CameraManager,
                                dualCamera: DualCamera,
                                targets: DualCameraOutputs,
                                executor: Executor = SERIAL_EXECUTOR,
                                callback: (CameraCaptureSession) -> Unit) {

        // Create 3 sets of output configurations: one for the logical camera, and
        // one for each of the physical cameras.
        val outputConfigsLogical = targets.first?.map { OutputConfiguration(it) }
        val outputConfigsPhysical1 = targets.second?.map {
            OutputConfiguration(it).apply { setPhysicalCameraId(dualCamera.physicalId1) } }
        val outputConfigsPhysical2 = targets.third?.map {
            OutputConfiguration(it).apply { setPhysicalCameraId(dualCamera.physicalId2) } }

        val outputConfigsAll = arrayOf(
            outputConfigsLogical, outputConfigsPhysical1, outputConfigsPhysical2)
            .filterNotNull().flatten()

        val sessionConfiguration = SessionConfiguration(SessionConfiguration.SESSION_REGULAR,
            outputConfigsAll, executor, object : CameraCaptureSession.StateCallback() {
                override fun onConfigured(session: CameraCaptureSession) = callback(session)
                override fun onConfigureFailed(session: CameraCaptureSession) = session.device.close()
            })


        openDualCamera(cameraManager, dualCamera, executor = executor) {
           it.createCaptureSession(sessionConfiguration)
        }
    }

DualCamera.kt 辅助类

data class DualCamera(val logicalId: String, val physicalId1: String, val physicalId2: String)

fun findDualCameras(manager: CameraManager, facing: Int? = null): Array<DualCamera> {
    val dualCameras = ArrayList<DualCamera>()

    manager.cameraIdList.map {
        Pair(manager.getCameraCharacteristics(it), it)
    }.filter {
        facing == null || it.first.get(CameraCharacteristics.LENS_FACING) == facing
    }.filter {
        it.first.get(CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES)!!.contains(
            CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES_LOGICAL_MULTI_CAMERA)
    }.forEach {
        val physicalCameras = it.first.physicalCameraIds.toTypedArray()
        for (idx1 in 0 until physicalCameras.size) {
            for (idx2 in (idx1 + 1) until physicalCameras.size) {
                dualCameras.add(DualCamera(
                    it.second, physicalCameras[idx1], physicalCameras[idx2]))
            }
        }
    }

    return dualCameras.toTypedArray()
}

fun findShortLongCameraPair(manager: CameraManager, facing: Int? = null): DualCamera? {

    return findDualCameras(manager, facing).map {
        val characteristics1 = manager.getCameraCharacteristics(it.physicalId1)
        val characteristics2 = manager.getCameraCharacteristics(it.physicalId2)

        val focalLengths1 = characteristics1.get(
            CameraCharacteristics.LENS_INFO_AVAILABLE_FOCAL_LENGTHS) ?: floatArrayOf(0F)
        val focalLengths2 = characteristics2.get(
            CameraCharacteristics.LENS_INFO_AVAILABLE_FOCAL_LENGTHS) ?: floatArrayOf(0F)

        val focalLengthsDiff1 = focalLengths2.max()!! - focalLengths1.min()!!
        val focalLengthsDiff2 = focalLengths1.max()!! - focalLengths2.min()!!

        if (focalLengthsDiff1 < focalLengthsDiff2) {
            Pair(DualCamera(it.logicalId, it.physicalId1, it.physicalId2), focalLengthsDiff1)
        } else {
            Pair(DualCamera(it.logicalId, it.physicalId2, it.physicalId1), focalLengthsDiff2)
        }

        // Return only the pair with the largest difference, or null if no pairs are found
    }.sortedBy { it.second }.reversed().lastOrNull()?.first
}

您可以在附加的屏幕截图上看到结果，左上角的 FOV 比在 Android 10 上运行的同一相机宽得多

这是 Android 10 的已知回归吗？有没有人注意到类似的行为？

Answer 1

我的理解：我在 Pixel 3 上遇到了同样的问题。看起来广角相机的框架在组合之前已经在 HAL 层中被裁剪了。实际上，FOV 并不完全相同，因为左右摄像头之间存在一些差异。然而，广角相机的默认变焦级别似乎会根据焦距而变化。

但我找不到任何有关它的官方文档。在 Android 10 中，它声称改进了物理相机的融合： https://developer.android.com/about/versions/10/features#multi-camera

解决方案：

如果您希望从广角前置摄像头访问原始数据，您可以为两个物理摄像头创建 2 个摄像头会话，而不是为逻辑摄像头创建一个会话。

更新：

您可以使用 setPhysicalCameraKey 重置缩放级别 https://developer.android.com/reference/android/hardware/camera2/CaptureRequest.Builder#setPhysicalCameraKey(android.hardware.camera2.CaptureRequest.Key%3CT%3E,%20T ,%20java.lang.String)