Faster command than "adb shell screencap"?

Question

I'm capturing an Android emulator screen using the command:

adb shell screencap -p /sdcard/screencap.png

But it is taking like 500ms to execute the command and save the png file, there is a faster way to capture the screen data? I don't really need the PNG file itself, just the 'image data', since I'm just creating the PNG and loading it into the .NET Bitmap class to read the pixels colors.

I need a faster way to capture the image, since I need like 10 images per second of the emulator screen to interact with it, so recording the screen to generate an video file is not a 'solution' for me.

Thanks

Answer 1

Old question, but you could try adb shell screencap screen.dump. This will skip the step to convert the file to png and will generate a file which can be read in Hex.

There are 12 bytes of header and then the file starts with the pixel colors at position (0,0) (top left) as RGBA.

The final size of the file depends on the size of your display.

Answer 2

Generally speaking, adb exec-out screencap >screenshotName.raw for getting raw image data and adb exec-out screencap -p >screenshotName.png for png-file. Both are not the fastest though: raw file is large and the speed is limited to adb bandwidth; png is much better in terms of file size, but may take too long to compress.

Better way to transmit data is adb exec-out "screencap | gzip -1" >screenshotName.gz. '-1' is the lowest compression level. You may further experiment with compression levels (from -1 to -9). Gzip way faster compresses the image, though resulting size is a bit larger, but still is good enough to faster transmit resulting data. I've tried some sample images (interface screens as well as full-screen photos) and gzip-method is always two times or more faster.

Answer 3

AFAIK, no such way exists except you write and run an app on the target device. Then send it back through network. In emulator situation, use adb forward.

See createVirtualDisplay for more details.

Answer 4

You can use adb shell screencap -j /sdcard/screencap.jpg

It will save image in the jpg format which for me was almost 3x faster than png.

Answer 5

I don't really need the PNG file itself, just the 'image data'

If you don't want the file to be saved, you don't need to specify image location:

adb shell screencap -p

Image data is PNG format printed out as a byte array. This is as fast as you can get with an adb command (typically 150ms on my PC with Bluestacks 4.2).

If you still want faster speed, this method using win32 api is perhaps the fastest. You need to make sure your emulator window is set to the correct size and visible on the screen.

Answer 6

image = check_output(["adb", "-s", emulator, "shell", "screencap -p"])
image = cv2.imdecode(np.fromstring(image, np.uint8), cv2.IMREAD_COLOR)

nearly 100 ms delay

Answer 7

I am also working with Memu emulator for image recognition purposes. If you are on Windows you can use various tools to program a screenshot function of a specific handle of the Memu window.

I get around 24-36FPS of screenshots by calling native windows functions.