我现在要移植alexa 到MT8516上。交叉编译sampleapp，是需要编译mediaplayer的
，于是我编译mediaplayer，编译时报错：
cmake ../MediaPlayer -DGSTREAMER_MEDIA_PLAYER=ON -DCMAKE_BUILD_TYPE=Debug -DARCH=arm
Creating the build directory for the MediaPlayer with build type: DEBUG
No keyword detector type specified, skipping build of keyword detector.
-- Checking for modules 'gstreamer-1.0>=1.8;gstreamer-app-1.0>=1.8'
CMake Error at /opt/oecore-x86_64/sysroots/x86_64-oesdk-linux/usr/share/cmake-3.7/Modules/FindPkgConfig.cmake:415 (message):
A required package was not found
Call Stack (most recent call first):
/opt/oecore-x86_64/sysroots/x86_64-oesdk-linux/usr/share/cmake-3.7/Modules/FindPkgConfig.cmake:588 (_pkg_check_modules_internal)
/home/jiantang/blackwarrior/avs-device-sdk-master/build/cmake/MediaPlayer.cmake:14 (pkg_check_modules)
/home/jiantang/blackwarrior/avs-device-sdk-master/build/BuildDefaults.cmake:25 (include)
GStreamerMediaPlayer/CMakeLists.txt:4 (include)
-- Configuring incomplete, errors occurred!
See also "/home/jiantang/blackwarrior/avs-device-sdk-master/MediaPlayer_build/CMakeFiles/CMakeOutput.log".
就是找不到gstreamer库，我现在已经有arm的gstreamer库了，请问怎么正确得加入到编译中去？
