Document platform build instructions

Add Linux, MSYS2, and MSVC build steps, including PCM backend selection and MSYS2 runtime packaging.

Author: dcherednik

README.md

@@ -5,41 +5,80 @@ Building:
 
 You need:
 * C++17 compiler.
-* cmake >= 3.1
-* libsndfiles 
+* CMake >= 3.1.
+* PCM input/output backend:
+  * `libsndfile` on Linux and MSYS2.
+  * Media Foundation on Windows with MSVC.
+* Python 3 (optional, only required to run the integration tests).
 
-In case of git clone command GHA submodule should be fetched:
+If the source was cloned with git, fetch submodules first:
 
 ```
 git submodule update --init --recursive
 ```
 
-binary:
+The PCM backend can be selected with `ATRACDENC_PCM_IO_BACKEND`.
+Supported values are `auto`, `mediafoundation`, and `libsndfile`.
+The default is `mediafoundation` for MSVC Windows builds and `libsndfile`
+everywhere else.
+
+Linux, Debian/Ubuntu based:
 
 ```
-cd src
-mkdir build
-cd build
-cmake ../
-make
+sudo apt update
+sudo apt install -y build-essential cmake libsndfile1-dev python3 googletest libgtest-dev
+
+cmake -S . -B build -DCMAKE_BUILD_TYPE=Release -DATRACDENC_PCM_IO_BACKEND=libsndfile
+cmake --build build -j"$(nproc)"
+ctest --test-dir build --output-on-failure
 ```
 
-Binary and tests (for development):
+The binary is created at `build/src/atracdenc`.
+
+Windows, MSYS2 MinGW64:
 
-Make sure google test library is installed
+Run the commands from the `MSYS2 MinGW x64` shell.
 
-debian:
 ```
-apt-get install libgtest-dev cmake-extras
+pacman -S --needed \
+    git \
+    mingw-w64-x86_64-cmake \
+    mingw-w64-x86_64-gcc \
+    mingw-w64-x86_64-gtest \
+    mingw-w64-x86_64-libsndfile \
+    mingw-w64-x86_64-ninja \
+    mingw-w64-x86_64-python
+
+cmake -S . -B build-msys2 -G Ninja \
+    -DCMAKE_BUILD_TYPE=Release \
+    -DATRACDENC_PCM_IO_BACKEND=libsndfile
+cmake --build build-msys2
+ctest --test-dir build-msys2 --output-on-failure
 ```
 
-Now we can build
+The binary is created at `build-msys2/src/atracdenc.exe`.
+
+To create a redistributable directory with required MSYS2 runtime DLLs and
+license files:
+
 ```
-cd test
-cmake ../
-make
+bash tools/package-msys2-runtime.sh build-msys2/src/atracdenc.exe dist-msys2
 ```
 
+Windows, MSVC:
+
+Install Visual Studio or Visual Studio Build Tools with the C++ desktop
+workload. Run the commands from an `x64 Native Tools Command Prompt for VS`.
+
+```
+cmake -S . -B build-msvc -G "Visual Studio 17 2022" -A x64 ^
+    -DATRACDENC_PCM_IO_BACKEND=mediafoundation
+cmake --build build-msvc --config Release
+ctest --test-dir build-msvc -C Release --output-on-failure
+```
+
+The binary is created at `build-msvc/src/Release/atracdenc.exe`.
+
 Usage:
 
 ATRAC1: