Android, Native OpenGL/OpenMAX, Screen capture

Question

Use-case

Mirror Android Screen to PC using USB

Potential (Native) Implementation Approaches

1. Using Android Open-Source, modify screenrecord for your needs and re-install on your Android device using ADB
2. Use well known native API such as OpenGL/OpenMAX to capture screen

Discussion

Approach #1 will certainly work ( under the shell account ), however, each time the Android OS is updated, the custom code will need to get updated to keep up with OS changes, with approach #2 the API stay fixed and there is no need to worry about OS changes, the question is whether it is possible to implement Mirroring solely using OpenGL/OpenMAX ?

Questions

Having the above said, what would be the best approach to mirror the android screen via USB ?

Answer 1

The screenrecord that ships with Android 5.0 "Lollipop" can send raw H.264 over ADB. The command line looks like:

adb shell screenrecord --output-format=h264 - | <player>

A few details are on the bigflake page. I've used it to mirror the screen onto a Linux workstation, but unfortunately I didn't save the VLC/mplayer command lines. Some player suggestions are here.

You can try to do uncompressed frames (--output-format=raw-frames), but at decent frame rates that easily overwhelms the ADB connection, even if the screen is tiny.

Source code is here.

Answer 2

As suggested by fadden, I have ended up patching through sreeenrecord disabling the time limitation and adding some code of my own ( enabling ADB over USB routing ), it works, BUT, req maintanance each time the OS is updated, I wish there would have been a way for using the Android Java framework as an ADB Shell Tool as this would considerably reduce the amount of un-documented buttons I am pressing...