使用Camera X时USB相机的初始化时间较长

Question

我正在制作一个应用程序，用于使用摄像头处理来自 USB 摄像头的 Orange pi5 上的帧，并在冷启动期间遇到了长时间初始化的问题。

这是我的相机初始化代码：

 private fun startCameraPreview() {

        cameraProviderFuture = ProcessCameraProvider.getInstance( requireContext() )

        cameraProviderFuture.addListener({
            val cameraProvider = cameraProviderFuture.get()
            bindPreview(cameraProvider) },
            ContextCompat.getMainExecutor(requireContext()) )
    }

     @SuppressLint("RestrictedApi")
     private fun bindPreview(cameraProvider : ProcessCameraProvider) {

        previewView = viewBinding.previewView
        previewView.implementationMode = PreviewView.ImplementationMode.COMPATIBLE
        previewView.scaleX = -1f

        val preview : Preview = Preview.Builder()
            .setResolutionSelector(
                ResolutionSelector.Builder().setResolutionStrategy(
                    ResolutionStrategy(Size(1080, 768),
                    ResolutionStrategy.FALLBACK_RULE_CLOSEST_HIGHER)
                ).build())
            .build()

        val selector = selectExternalOrBestCamera(cameraProvider) //For Usb camera Access
        preview.setSurfaceProvider( previewView.surfaceProvider )

        val strategy = ResolutionStrategy(Size(640, 480),
            ResolutionStrategy.FALLBACK_RULE_CLOSEST_HIGHER)

        val imageFrameAnalysis = ImageAnalysis.Builder()
            .setResolutionSelector(ResolutionSelector.Builder().setResolutionStrategy(strategy).build())
            .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
            .setOutputImageFormat(ImageAnalysis.OUTPUT_IMAGE_FORMAT_RGBA_8888)
            .build()

        imageFrameAnalysis.setAnalyzer(Executors.newSingleThreadExecutor(), frameAnalyser )
        cameraProvider.bindToLifecycle(this as LifecycleOwner, selector!!, preview , imageFrameAnalysis  )
    }

    

我还使用官方文档中的代码来访问 USB 相机选择器

fun selectExternalOrBestCamera(provider: ProcessCameraProvider):CameraSelector? {

        val cam2Infos = provider.availableCameraInfos.map {
            Camera2CameraInfo.from(it)
        }.sortedByDescending {
            // HARDWARE_LEVEL is Int type, with the order of:
            // LEGACY < LIMITED < FULL < LEVEL_3 < EXTERNAL
            it.getCameraCharacteristic(CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL)
        }

        return when {
            cam2Infos.isNotEmpty() -> {
                CameraSelector.Builder()
                    .addCameraFilter {
                        it.filter { camInfo ->
                            // cam2Infos[0] is either EXTERNAL or best built-in camera
                            val thisCamId = Camera2CameraInfo.from(camInfo).cameraId
                            thisCamId == cam2Infos[0].cameraId
                        }
                    }.build()
            }
            else -> null
        }
    }

当我第一次启动应用程序时，我收到 6 次。

2024-03-05 15:58:14.010 14845-14906 CameraRepository                              D  Added camera: 0
2024-03-05 15:58:14.012 14845-14906 Camera2CameraInfo                             I  Device Level: INFO_SUPPORTED_HARDWARE_LEVEL_EXTERNAL
2024-03-05 15:58:14.012 14845-14906 CameraValidator                               D  Verifying camera lens facing on rk3588s_s, lensFacingInteger: null
2024-03-05 15:58:14.013 14845-14906 CameraValidator                              E  Camera LensFacing verification failed, existing cameras: [Camera@e0778e4[id=0]]
2024-03-05 15:58:14.014 14845-14906 CameraX                                       W  Retry init. Start time 9251708 current time 9253283
                                                                                                    androidx.camera.core.impl.CameraValidator$CameraIdListIncorrectException: Expected camera missing from device.
                                                                                                        at androidx.camera.core.impl.CameraValidator.validateCameras(CameraValidator.java:97)
                                                                                                        at androidx.camera.core.CameraX.lambda$initAndRetryRecursively$2$androidx-camera-core-CameraX(CameraX.java:334)
                                                                                                        at androidx.camera.core.CameraX$$ExternalSyntheticLambda3.run(Unknown Source:10)
                                                                                                        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
                                                                                                        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
                                                                                                        at java.lang.Thread.run(Thread.java:920)
                                                                                                    Caused by: java.lang.IllegalArgumentException: No available camera can be found
                                                                                                        at androidx.camera.core.CameraSelector.select(CameraSelector.java:94)
                                                                                                        at androidx.camera.core.impl.CameraValidator.validateCameras(CameraValidator.java:83)
                                                                                                        at androidx.camera.core.CameraX.lambda$initAndRetryRecursively$2$androidx-camera-core-CameraX(CameraX.java:334) 
                                                                                                        at androidx.camera.core.CameraX$$ExternalSyntheticLambda3.run(Unknown Source:10) 
                                                                                                        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167) 
                                                                                                        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641) 
                                                                                                        at java.lang.Thread.run(Thread.java:920) 

此相机初始化并显示以下消息后：

设备可能会少报摄像头数量。完成初始化任务，因为我们已经达到了最大重试次数。

对此有什么帮助吗？

Added camera: 0
2024-03-05 15:58:15.030 14845-14906 Camera2CameraInfo                             I  Device Level: INFO_SUPPORTED_HARDWARE_LEVEL_EXTERNAL
2024-03-05 15:58:15.031 14845-14906 CameraValidator                               D  Verifying camera lens facing on rk3588s_s, lensFacingInteger: null
2024-03-05 15:58:15.032 14845-14906 CameraValidator                              E  Camera LensFacing verification failed, existing cameras: [Camera@10741b2[id=0]]
2024-03-05 15:58:15.032 14845-14906 CameraX                                      E  The device might underreport the amount of the cameras. Finish the initialize task since we are already reaching the maximum number of retries.
2024-03-05 15:58:15.083 14845-14845 CameraOrientationUtil                        D  getRelativeImageRotation: destRotationDegrees=0, sourceRotationDegrees=90, isOppositeFacing=false, result=90
2024-03-05 15:58:15.085 14845-14845 CameraOrientationUtil                         D  getRelativeImageRotation: destRotationDegrees=0, sourceRotationDegrees=90, isOppositeFacing=false, result=90
2024-03-05 15:58:15.094 14845-14845 DynamicRangeResolver                          D  Resolved dynamic range for use case androidx.camera.core.Preview-1b649f9e-f19f-43f5-8882-7ace2058df35 to no compatible HDR dynamic ranges.
                                                                                                    DynamicRange@d8ad747{encoding=UNSPECIFIED, bitDepth=0}
                                                                                                    ->
                                                                                                    DynamicRange@c2bc286{encoding=SDR, bitDepth=8}
2024-03-05 15:58:15.099 14845-14845 CameraOrientationUtil                         D  getRelativeImageRotation: destRotationDegrees=0, sourceRotationDegrees=90, isOppositeFacing=false, result=90
2024-03-05 15:58:15.101 14845-14845 DeferrableSurface                             D  Surface created[total_surfaces=1, used_surfaces=0](androidx.camera.core.processing.SurfaceEdge$SettableSurface@df18112}
2024-03-05 15:58:15.103 14845-14845 DeferrableSurface                             D  Surface created[total_surfaces=2, used_surfaces=0](androidx.camera.core.SurfaceRequest$2@4e29c5e}
2024-03-05 15:58:15.104 14845-14845 DeferrableSurface                             D  New surface in use[total_surfaces=2, used_surfaces=1](androidx.camera.core.SurfaceRequest$2@4e29c5e}
2024-03-05 15:58:15.104 14845-14845 DeferrableSurface                            D  use count+1, useCount=1 androidx.camera.core.SurfaceRequest$2@4e29c5e

我的 CameraX gradle 依赖项：

// CameraX
    def camerax_version = "1.3.1"
    implementation "androidx.camera:camera-core:${camerax_version}"
    implementation "androidx.camera:camera-camera2:${camerax_version}"
    implementation "androidx.camera:camera-lifecycle:${camerax_version}"
    implementation "androidx.camera:camera-video:${camerax_version}"

    implementation "androidx.camera:camera-view:${camerax_version}"
    implementation "androidx.camera:camera-extensions:${camerax_version}"

我尝试添加

@OptIn(ExperimentalCamera2Interop::class)

对实验方法的注释，我尝试明确指定CameraSelector的镜头类型

.requireLensFacing(LENS_FACING_FRONT/BACK/EXTERNAL)

- 没有结果，只有崩溃。 我对这种情况的看法：CameraValidator 无法接受来自 USB 摄像头的镜头值。 有什么帮助吗？

Answer 1

您的设备报告的系统属性与其实际相机硬件之间似乎不匹配。这导致 CameraX 尝试初始化根本不存在的相机。

具体来说，听起来您的设备可能指示存在前置摄像头和/或主摄像头，即使您只连接了外部摄像头。对于正确配置的设备，在这种情况下，PackageManager.hasSystemFeature(PackageManager.FEATURE_CAMERA_FRONT) 和 PackageManager.hasSystemFeature(PackageManager.FEATURE_CAMERA) 都应返回 false。

此类问题在开发设备上更为常见，这些设备不一定经过与 CTS 认证设备相同的严格配置和测试。

最直接的解决方案是调整设备上的系统属性以匹配物理相机设置。这将确保 CameraX 仅尝试初始化实际存在的相机。