使用CameraX时，Facebase MLKit面部检测在前置摄像头中失败

Question

我正在尝试使用Firebase MLKit和CameraX ImageAnalysis实现人脸检测。使用后置摄像头时它工作正常，但是当我尝试使用前置摄像头时，它什么也没检测到：

val config = PreviewConfig.Builder()
.setLensFacing(CameraX.LensFacing.FRONT)
.build()
val previewUseCase = Preview(config)
previewUseCase.setOnPreviewOutputUpdateListener { previewOutput ->
viewFinder.post {
removeView(viewFinder)
addView(viewFinder, 0)
viewFinder.surfaceTexture = previewOutput.surfaceTexture
updateTransform(previewOutput)
}
}
val highAccuracyOpts = FirebaseVisionFaceDetectorOptions.Builder()
.setPerformanceMode(FirebaseVisionFaceDetectorOptions.ACCURATE)
.build()
val detector = FirebaseVision.getInstance().getVisionFaceDetector(highAccuracyOpts)
val imageAnalysisConfig = ImageAnalysisConfig.Builder()
.setImageReaderMode(ImageAnalysis.ImageReaderMode.ACQUIRE_LATEST_IMAGE)
.build()
val imageAnalysis = ImageAnalysis(imageAnalysisConfig).apply {
setAnalyzer(
Executors.newSingleThreadExecutor(),
ImageAnalysis.Analyzer { image, rotationDegrees ->
if (image.image != null && isBusy.compareAndSet(false, true)) {
val visionImage = FirebaseVisionImage.fromMediaImage(image.image!!, degreesToFirebaseRotation(rotationDegrees))
detector.detectInImage(visionImage)
.addOnSuccessListener { faces ->
// faces.size always zero when using front camera
Timber.d("${faces.size}")
isBusy.set(false)
}
.addOnFailureListener { error ->
Timber.d("$error")
}
}
})
}
CameraX.bindToLifecycle(lifecycleOwner, previewUseCase, imageAnalysis)

我在诺基亚 8.1 和 Android 10 上进行了测试。我尝试了不使用CameraX的 https://github.com/firebase/quickstart-android/tree/master/mlkit，并且可以与前置摄像头配合使用。

Answer 1

通过将ImageAnalysislensfacing设置为CameraX.LensFacing.FRONT来解决它：

val imageAnalysisConfig = ImageAnalysisConfig.Builder()
.setLensFacing(CameraX.LensFacing.FRONT)
.setImageReaderMode(ImageAnalysis.ImageReaderMode.ACQUIRE_LATEST_IMAGE)
.build()