Shot in the dark, but has anyone ever had to show a usb camera preview in an Android app? Camerax li...

# random

[Colton Idle]

Shot in the dark, but has anyone ever had to show a usb camera preview in an Android app? Camerax library doesn't seem to support usb cams?

[Chris Fillmore]

I was curious too, so I looked around and found this https://issuetracker.google.com/issues/162382076?pli=1

[Chris Fillmore]

Depending on your use case you might consider sending video over webrtc on local wifi or something. That would be a hassle on its own but might be more reliable

[Chris Fillmore]

What is your use case anyway? Are you taking pictures or capturing video?

[Pablichjenkov]

There are 2 APIs to access USB. The Android usb accessory API where Android act as a host. And the standard USB API where Android act as a device. What protocol does the camera uses?
Once connected I assume you would copy the raw buffers from the camera device to the camera preview Android buffer, just guessing.

[Colton Idle]

I basically have a usb webcam that needs to connect to an android device that doesn't have a camera. I'm taking pictures, but need a live video feed from the camera to show as a preview.

[Chris Fillmore]

What’s the camera being used for?

[Chris Fillmore]

So, to your original question, I think the answer is no, you can’t do this with CameraX. In general any low-level camera work will require camera2

[Chris Fillmore]

Have you tried with camera2?

[Colton Idle]

I have not tried with camera2. I thought camerax was camera2 lol

[Colton Idle]

or wasn't there like camerax2 or something

[Chris Fillmore]

CameraX is built on top of camera2

[Colton Idle]

oh gotcha. TIL

[Chris Fillmore]

Provides more high-level APIs

[Colton Idle]

interesting. so maybe ill have to try that

[Colton Idle]

I was able to get camera preview to show when using this library. but i can't use this library long term as it wasn't approved by legal department. https://github.com/jiangdongguo/AndroidUSBCamera

[Colton Idle]

I also tried logging packageManager.hasSystemFeature(PackageManager.FEATURE_CAMERA_EXTERNAL) on our specific device that we have to use and it reports as false.

[Colton Idle]

so i guess my device doesn't handle external cameras... so camera2 wouldn't pick it up anyway?

[Chris Fillmore]

Spend some time reading around stack overflow and such, e.g.
https://stackoverflow.com/questions/57846505/accessing-a-usb-camera-using-android-camera2-api

[Chris Fillmore]

You might get a sense for what’s required

[Colton Idle]

yeah. i read through the top answer yesterday

[Chris Fillmore]

Instead of trusting hasSystemFeature, just try to use the camera and see if it works

[Colton Idle]

this sample app was nice https://github.com/android/camera-samples

[Colton Idle]

but okay. at least i wasn't missing something basic here.

[Colton Idle]

well camerax and camera2 apis being different was something i was missing lol

[Chris Fillmore]

No not at all. Trying to use a USB camera definitely qualifies as low-level camera work, so using camera2 makes sense

[Chris Fillmore]

Sorry the above was in response to this

at least i wasn’t missing something basic here.

[Colton Idle]

Cool. That does give me something to work off of. thank you for your insight!

[Chris Fillmore]

Let me know if it works for you. I’ve done camera work as well so I’d be curious to know the results

[Chris Fillmore]

What happens when you plugin the webcam and call this:
https://developer.android.com/reference/android/hardware/camera2/CameraManager#getCameraIdList()

[Chris Fillmore]

Then use the camera ids from that all to query the camera characteristics:
https://developer.android.com/reference/android/hardware/camera2/CameraManager#getCameraCharacteristics(java.lang.String)

[Chris Fillmore]

The returned CameraCharacteristics will allow you to query a bunch of fields:

https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics#fields_1

[Chris Fillmore]

It also includes CameraMetadata which includes this field, which I think you’re interested in:
https://developer.android.com/reference/android/hardware/camera2/CameraMetadata#LENS_FACING_EXTERNAL

[Chris Fillmore]

So… something like this

val cameraManager = context.getSystemService(Context.CAMERA_SERVICE) as CameraManager
val cameraIds = cameraManager.cameraIdList
val externalCamera = cameraIds.find {  cameraId ->
  cameraManager.getCameraCharacteristics(cameraId).get(CameraMetadata.LENS_FACING_EXTERNAL) === true
}

if (externalCamera != null) {
  cameraManager.openCamera(externalCamera, object : CameraDevice.StateCallback() {
    override fun onOpened(p0: CameraDevice) {
      TODO("Not yet implemented")
    }

    override fun onDisconnected(p0: CameraDevice) {
      TODO("Not yet implemented")
    }

    override fun onError(p0: CameraDevice, p1: Int) {
      TODO("Not yet implemented")
    }
  }, null)
}

[Chris Fillmore]

If externalCamera in the above ends up being null, just try exploring the API a bit. Different device vendors will have some different behaviour, so also don’t hesitate to try different devices

[Colton Idle]

Cool. I will try this out when im done putting out this fire for the day. thank you so much Chris!

[Chris Fillmore]

Note that the above doesn’t include any of the code for creating a capture session, using SurfaceView, etc. If you’ve never used camera2 you’ll need to spend a bit of time on that

[Colton Idle]

Yep. All I really need at this point is to know whether the android device detects the usb device as a potential camera. I have the usb permission prompt working so it does tell me when I plug the camera in.

[louiscad]

There should be a way to access external cameras with CameraX, granted the device already sees them with Camera2 cameraIdList

[Chris Fillmore]

Yeah I should clarify, I’m not familiar with CameraX capabilities. I may have overlooked something