I would like to access the YUV images of a video, and passing a ImageReader surface to a MediaCodec (as refered in the documentation) looked like a really smart way to do it. However, i can't make sense of the data inside the Image instance supplied by the onImageAvailable callback. Just looking at its Y plane, it looks to be mostly 0 values, no matter what is the video i provide.
I read some #fadden comments that looked a bit old by now, referring that the ImageReader surface was not available yet for MediaCodec, is this still the case? Did anyone succeeded in implementing a MediaCodec decoding to a ImageReader surface solution?
To illustrate, i was hopping for the Y plane to be like this:
and it comes out as:
Thanks for any pointers
I met the same problem. In my case, it is because I did not specicify the MediaCodec to output the same format image as the ImageReader.
int imageFormat = ImageFormat.YUV_420_888;
mImageReader = ImageReader.newInstance(
videoFormat.getInteger(MediaFormat.KEY_WIDTH),
videoFormat.getInteger(MediaFormat.KEY_HEIGHT),
imageFormat,
3
);
// I add the following line of code.
videoFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Flexible);
// Then initialize the MediaCodec with videoFormat.
Related
Im currently trying to display a video frame using opengl.
So far it works but I have some color problem.
Im using this as my
Reference for my logic
I have this code
//YUV420SP data
uint8_t *decodedBuff = AMediaCodec_getOutputBuffer(d->codec, status, &bufSize);
buildTexture(decodedBuff, decodedBuff+w*h, decodedBuff+w*h, w, h);
renderFrame();
but it displays with wrong color.
decodedBuff = Y
decodedBuff+w*h = U
decodedBuff+w*h*5 = V
but this separation formula is for YUV420P.
Do you guys happen to know whats for YUV420SP?
Your help is very much appreciated
If you are doing it this way you are doing it wrong. You should never manually read raw data from video surfaces in fragment shaders.
Generate a SurfaceTexture, bind it to an OpenGL ES texture, and use EGL_image_external to access the texture via an external image sampler.
This will give you direct access to the video data in your shader, including automatic handling of the memory format and color conversion, in many cases for "free" because it's backed by GPU hardware acceleration.
I followed the Android Studio tutorial to get the CameraPreview to work (Camera API Android Developer Guide). This works fine for me and i can view the camera stream in my FrameLayout.
But I would like to get the RGB values from a specific Pixel in the Preview everytime it changes. I did not find a method which gives me the previewImage as a bitmap and was not able to understand the usage of the onPreviewFrame method
#Override
public void onPreviewFrame(byte[] data, Camera camera) {}
How can I get the RGB values from a Camerapreview Pixel?
If you are using the Camera2 API, you can implement the ImageReader.OnImageAvailableListener class in your application. After that, you override the onImageAvailable function , which gets an ImageReader as argument. Then you can access the image just recorded with imageReader.acquireNextImage().
With either API, you need to handle processing YUV data yourself, unfortunately.
Camera devices natively produce YUV data, not RGB, so the API doesn't spend extra resources to auto-convert the data. The main easy exception is piping data to the GPU, where the GPU driver auto-converts YUV to RGB for you within your pixel shader.
But if you're just in regular app code, you need to parse the data.
For the deprecated android.hardware.Camera API, the output is NV21 by default, and you can usually select YV12 as another option.
The wikipedia article on YUV is relatively helpful: https://en.wikipedia.org/wiki/YUV
But it does have the wrong conversion coefficients for YUV->RGB conversion; they should be:
R = Y + 1.402 (Cr-128)
G = Y - 0.34414 (Cb-128) - 0.71414 (Cr-128)
B = Y + 1.772 (Cb-128)
(Cb = U, Cr = V)
You can also take a look at this stackoverflow post:
Extract black and white image from android camera's NV21 format
which has code that looks to be correct for the conversion.
ImageReader and SurfaceTexture is async from app side. SurfaceTexture.OnFrameAvailableListener and ImageReader.OnImageAvailableListener are coming in different time.
Now I will make an AR App. I calculate the object motion with the image from ImageReader and output the object motion information. On the other hand. Call updateTexImage to render background. But the question is the object motion has obviously latency behind background rendering.
The workflow is below:
Camera2->ImageReader->calculate object motion -> Render a virtual object with object motion information
Camera2->SufaceTexture->Render backgroud with updateTexImage
the upateTexImage and rendering-virtual-object is call in Render.onDrawFrame
So obviously the question is how to Sync ImageReader and SurfaceTexture with Android Camera2 output
The easiest option is not to use two data paths, and instead either do image analysis on the SurfaceTexture buffer (either in EGL or read back from GPU to CPU for analysis), or use the ImageReader buffer to draw everything with.
If that's not feasible, you need to look at the timestamps (https://developer.android.com/reference/android/graphics/SurfaceTexture.html#getTimestamp() and https://developer.android.com/reference/android/media/Image.html#getTimestamp()). For the same capture, the two paths will have the same timestamp, so you can queue up and synchronize your final drawing by matching them up.
I am bit confused after reading lot of resources in the internet.
1) I have a TextureView in the Application. ((tv))
2) I have associated SurfaceTextureLister to ((tv)).
tv.setSurfaceTextureListener(new TextureView.SurfaceTextureListener() {
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
mySurface = new Surface(surface); => This surface is sent to native layer.
....
}
3) Passing this mySurface surface into the native, I get ANativeWindow for this surface, and use ANativeWindow_lock and ANativeWindow_unlockAndPost to copy the data into the surface.
So far so good. it is displaying the data what i have copied into the ANativeWindow.
Now, i want to record all these frames into into MP4 format in a file.
What i did?
1)
I have used the below link for the reference:
http://www.bigflake.com/mediacodec/EncodeAndMuxTest.java.txt
2)
I have retrieived a surface from the mediacodec encoder, and passed to the native to copy the same way as i have copied into the display surface. I see no output in the mp4 file. just a black screen.
QUESTION:
1) Is this the right approach ? what i mean is you have a raw data,
copy the this data into two surfaces, one has come from application TextureView, and the other one is from mediacodec encoder surface.
2)
Or, Did i overlook any other easy way of recording the data into mp4 format ?
3)
Or, Any concepts did i miss completely to look at ?
Kindly provide your valuable input.
I am reading the code about Android Camera2 APIs from here:
https://github.com/googlesamples/android-Camera2Basic
And it is confusing in this lines:
https://github.com/googlesamples/android-Camera2Basic/blob/master/Application/src/main/java/com/example/android/camera2basic/Camera2BasicFragment.java#L570-L574
that the previewRequest builder only add surface, which is the TextureView to show, as target. But the following line actually add both as the targets. As I understand, this should not fire the "OnImageAvailable" Lisenter during preview, no? So why this add the imagereader's surface here?
I tried to removed this imagereader's surface here but got error when I really want to capture an image.....
SOOO CONFUSING!!!
You need to declare all output Surfaces that image data might be sent to at the time you create a CameraCaptureSession. This is just the way the framework is designed.
Whenever you create a CaptureRequest, you add a (list of) target output Surface(s). This is where the image data from the captured frame will go- it may be a Surface associated with a TextureView for displaying, or with an ImageReader for saving, or with an Allocation for processing, etc. (A Surface is really just a buffer which can take the data output by the camera. The type of object that buffer is associated with determines how you can access/work with the data.)
You don't have to send the data from each frame to all registered Surfaces, but it has to be sent to a subset of them. You can't add a Surface as a target to a CaptureRequest if it wasn't registered with the CameraCaptureSession when it was created. Well, you can, but passing it to the session will cause a crash, so don't.