Fail when compiling Android library Libwhisper.a from sources

[Dan0398]

I cloned your repository and run from Win11 editor. It works awesome.
But when i built it for Android (Google Pixel 3a) it works very slow. Simple phrace 3 seconds length processed over 30 seconds.
Speedup feature throws an error (-1) even in editor.

Turning on more than 1 thread change processing time to 16 seconds. Better, but still not for production app.

But i saw how Whisper for android works in another repos:
https://www.youtube.com/watch?v=w9pohi9NQrg
This video is part of demo in this repo:
https://github.com/vilassn/whisper_android

Method that runs so slow in on Whisper side. As solution i selected to try to recompile a library with few arguments that can tweak perfomance.

What i tried to do:

1. Cloned the original whisper.cpp repository, but 1.5.4 checkout

2. In "CMakeLists.txt" i added few lines on top because it doesn't processes without it:

set(CMAKE_C_COMPILER_WORKS 1)
set(CMAKE_CXX_COMPILER_WORKS 1)
set(CMAKE_THREAD_LIBS_INIT "-lpthread")

3. Run Cmake with this args:
   cmake -DCMAKE_TOOLCHAIN_FILE="E:\Programs\Unity\2022.3.10f1\Editor\Data\PlaybackEngines\AndroidPlayer\NDK\build\cmake\android.toolchain.cmake"
   -DANDROID_ABI=arm64-v8a
   -DBUILD_SHARED_LIBS=OFF
   -DWHISPER_BUILD_TESTS=OFF
   -DWHISPER_BUILD_EXAMPLES=OFF
   -DANDROID_PLATFORM=29
   -DANDROID_NATIVE_API_LEVEL=29
   -DCMAKE_BUILD_TYPE=Release
   -G "MinGW Makefiles"
   -DCMAKE_MAKE_PROGRAM="E:\whisper\CMakeLists.txt"

4. Run Makefile with Mingw32.

As result i got a "libwhisper.a" file. But it weight 1,43 MB, when your precompiled version weight 13,9 MB.
When i tried to build .apk file with mine library i got an error
"android error: undefined symbol: stdout" (and stderr).

What i does wrong?

Win 11, Unity 2022.3.10f1, CMake 3.29, MinGW 3.80.3.

[Macoron]

The easiest way to recompile whisper.cpp from source is to use Github Action. It uses ready-to-use instances, so you won't have any problems with build tools. You can create your own fork and run "Build C++" action there. Check readme for more info.

If you still struggle to recompile whisper.cpp on your local machine, maybe it worth trying to ask guys in original whisper.cpp repo. I never tried to build Android libs of whisper.cpp on Windows, so I won't be able to help what might be a problem.

As for making Android work faster, check #47. It is known problem with whisper.cpp, which wasn't addressed by original dev team yet.