Using minicap for Fast Android Screen Capture

During recent automation‑testing work I found the built‑in Android screencap command too slow, so I explored the classic tool minicap and would like to share my learning experience.

minicap is a dependency of the STF (Smartphone Test Farm) framework; it streams real‑time screen data from Android devices to a web client. The project has been actively maintained on GitHub for nearly three years, recently updated to support Android 8.1, and can achieve 30‑40 FPS on capable phones.

On a ZUK Z2 Pro device the native screencap takes more than 4 seconds to capture a screenshot, while minicap completes the same task in about 190 ms. minicap uses libjpeg‑turbo for compression, producing images around 100 KB at 1080p, compared with the 2 MB size of screencap output.

Installation: minicap is an NDK‑developed native tool consisting of an executable and a minicap.so library. Because minicap.so calls private APIs, it must be compiled against the AOSP source tree. You can compile it yourself or download pre‑built binaries from GitHub . No socket configuration is required for basic screenshot usage; for advanced setups see the official repository .

To push the binaries to the device, first determine the device’s ABI and SDK version:

adb shell getprop ro.product.cpu.abi | tr -d '\r'

adb shell getprop ro.build.version.sdk | tr -d '\r'

Then push the matching executable and library and make the executable runnable:

adb push libs/$ABI/minicap /data/local/tmp/

adb push jni/minicap-shared/aosp/libs/android-$SDK/$ABI/minicap.so /data/local/tmp/

chmod 777 /data/local/tmp/minicap

Running minicap:

adb shell LD_LIBRARY_PATH=/data/local/tmp /data/local/tmp/minicap -P 1080x1920@1080x1920/0 –t

If the command returns no error, the tool is installed correctly and ready to capture.

To save a screenshot and pull it back to the host you can use a simple Python script (shown in the original article) that invokes the above command, captures the output image, and pulls it via adb pull .

In summary, this guide outlines how to use minicap outside of STF, helping newcomers avoid common pitfalls and integrate fast screen capture into testing or development pipelines. A future article will dive deeper into the minicap source code and compare different screenshot solutions.