Installation error-from source-windows

Hi there,

Thanks for open-sourcing such an awesome package!

I plan to use the GPU version, but recently experienced trouble installing the package from the source:

I followed the instructions in the README.md, and here is what I did:

first install git, cmake and ffmpeg (python already installed)
cd my-workspace
git clone --recursive https://github.com/dmlc/decord
cd decord
mkdir build
cd build
cmake -DCMAKE_CXX_FLAGS="/DDECORD_EXPORTS" -DCMAKE_CONFIGURATION_TYPES="Release" -G "Visual Studio 15 2017 Win64" -DFFMPEG_DIR:PATH="C:/ffmpeg/bin/" ..
open `decord.sln` in VS2017 and click build solution.

The output is "========== Build: 2 succeeded, 1 failed, 0 up-to-date, 4 skipped =========="
I encountered the following error message:

2>h:\decord_source\decord\include\decord\../../src/video/ffmpeg/ffmpeg_common.h(23): fatal error C1083: Cannot open include file: 'libavcodec/avcodec.h': No such file or directory (compiling source file H:\decord_source\decord\src\audio\audio_interface.cc)
2>h:\decord_source\decord\include\decord\../../src/video/ffmpeg/ffmpeg_common.h(23): fatal error C1083: Cannot open include file: 'libavcodec/avcodec.h': No such file or directory (compiling source file H:\decord_source\decord\src\audio\audio_reader.cc)

I was wondering if you could help me to figure out what causes the issue.

In addition, I wonder whether additional configurations are needed in order to use the source-installed package in pycharm's conda environment.

Many thanks!