I am new to Android, i want to take pictures in background without surface view/preview. I have searched online but the methods don't seem working for me. I want to use the latest Camera2 API.
Regards!
Muhammad Awais
Just create an ImageReader, and a camera capture session with that ImageReader's Surface. No need to have a SurfaceView or TextureView as well.
You'll need to stream some number of captures before starting to save any, though, to ensure that the auto-exposure/focus/etc routines of the camera have time to converge.
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I want to extend an app from Camera1 to Camera2 depending on the API. One core mechanism of the app consists in taking preview pictures at a rate of about 20 pics per second. With Camera1 I realized that by creating a SurfaceView, adding a Callback on its holder and after creation of the surface accessing the preview pics via periodic setOneShotPreviewCallbacks. That was pretty easy and reliable.
Now, when studying Camera2, I came "from the end" and managed to convert YUV420_888 to Bitmap (see YUV420_888 to Bitmap Conversion ). However I am struggling now with the "capture technique". From the Google example I see that you need to make a "setRepeating" CaptureRequest with CameraDevice.TEMPLATE_PREVIEW for displaying the preview e.g. on a surface view. That is fine. However, in order to take an actual picture I need to make another capture request with (this time) builder.addTarget(imageReader.getSurface()). I.e. data will be available within the onImageAvailable method of the imageReader.
The problem: the creation of the captureRequest is a rather heavy operation taking about 200ms on my device. Therefore, the usage of a capture request (whether with Template STILL_CAPTUR nor PREVIEW) can impossibly be a feasible approach for capturing 20 images per second, as I need it. The proposals I found here on SO are primarily based on the (educationally moderately efficient) Google example, which I don't really understand...
I feel the solution must be to feed the ImageReader with a contiuous stream of preview pics, which can be picked from there in a given frequency. Can someone please give some guidance on how to implement this? Many thanks.
If you want to send a buffer to both the preview SurfaceView and to your YUV ImageReader for every frame, simply add both Surfaces to the repeating preview request as targets.
Generally, a capture request can target any subset (or all) of the
session's configured output targets.
Also, if you do want to only capture an occasional frame to your YUV ImageReader with .capture(), you don't have to recreate the capture request builder each time; just call .build() again on the same builder, or just reuse the actual constructed CaptureRequest if you're not changing any settings.
Even with this occasional capture, you probably want to include the preview Surface as a target in the YUV capture request, so that there's no skipped frame in the displayed preview.
The Media Projection package is new Lollipop, and allows an app to capture the device's screen in realtime for streaming to video. I was hoping this could also be used to capture a single still screenshot, but so far I have not been successful. Of course, the first frame of a captured video could work, but I'm aiming for a perfect, lossless screenshot matching the pixel resolution of the device. A still from a captured video cannot provide that.
I've tried a lot of things, but the closest I came to a solution was to first launch an invisible activity. This activity then follows the API example for starting screen capture, which can include asking the user's permission. Once screen capture is enabled, the screen image is live in a SurfaceView. However, I cannot find a way to capture a bitmap from the SurfaceView. There are lots of questions and discussions about this, but no solutions seem to work, and there is some evidence that it is impossible.
Any ideas?
You can't capture the contents of a SurfaceView.
What you can do is replace the SurfaceView with a Surface object that has an in-process consumer, such as SurfaceTexture. In the android-ScreenCapture example linked from the question, mMediaProjection.createVirtualDisplay() wants a Surface to send images to. If you create a SurfaceTexture, and use that to construct a Surface, the images generated by the MediaProjection will be available from an OpenGL ES texture.
If GLES isn't your thing, the ImageReader class can be used. It also provides a Surface that can be passed to createVirtualDisplay(), but it's easier to access the pixels from software.
I want to image process android front camera frames inside a service.
I use OpenCV and therefore using CameraBridgeViewBase which asks for camera view.
I dont want to record the video. i need to process each frame in real time.
any solution ?
According to the examples of fadden available (have a look here), you can do it using a SurfaceTexture instead of a SurfaceView for getting the frames. It was also answered here before, but unfortunately never validated.
I could get frames from a service this way.
As you may notice, camera in android phones stops working when we minimize it (for example when we start a new application). My question is: Is there any way to create an app with android camera, which records even if we minimize it so it could be recording videos while we are doing something different on our phone? Or may be it is only possible if we create such camera without using MediaStore? If you share some links or code which might help me, I'll be grateful. Thanks in advance.
I believe the answer to this is that one must use
public final void setPreviewTexture (SurfaceTexture surfaceTexture)
Added in API level 11
Sets the SurfaceTexture to be used for live preview.
Either a surface or surface texture is necessary for preview,
and preview is necessary to take pictures.
from https://developer.android.com/reference/android/hardware/Camera.html . And
from https://developer.android.com/reference/android/graphics/SurfaceTexture.html :
The image stream may come from either camera preview or video decode.
A SurfaceTexture may be used in place of a SurfaceHolder when specifying the
output destination of a Camera or MediaPlayer object. Doing so will cause all the
frames from the image stream to be sent to the SurfaceTexture object rather than
to the device's display.
and I would really like to try this and send you some code, but I have no phone more recent than gingerbread, and this was introduced with honeycomb.
Using a surface associated with an Activity, surfaceDestroyed is called sometime between onPause and onStop when the Activity is being minimised, although, oddly, not when the phone is being put to sleep: How SurfaceHolder callbacks are related to Activity lifecycle? But I hope that a surfaceTexture is not destroyed in this way.
I am developing an application where I have to take picture without using Media intent i-e without previewing this camera.How can I do this can anyone help me in this regard.
waiting for your reply
Altaf
You cannot take a picture without a preview. Whether it is the preview offered by the Intent or it is a preview that you create yourself with a SurfaceView when you use the Camera object, there has to be a preview.
Just use takePicture() directly on the camera object:
http://developer.android.com/reference/android/hardware/Camera.html#takePicture
I believe some of the older devices wouldn't capture correctly unless preview was setup, but I don't think that's an issue any more. And if you are looking to target devices that require preview you can just resize the preview surface to a single pixel somewhere and put another control on top of it. Still eats resources, but shouldn't be visible.