這個bug卡了半天，這裡記錄一下

Error using VideoReader/init (line 619) Could not read file due to an unexpected error. Reason: Unable to initialize the video obtain properties

Error in VideoReader (line 172)
            obj.init(fileName);

環境：Ubuntu16.04

參考：stackoverflow

首先安裝gstreamer0.10-ffmpeg

1 sudo
 
 add-apt-repository ppa:mc3man/gstffmpeg-keep
2 sudo apt-get update
3 sudo apt-get install gstreamer0.10-ffmpeg

重啟MATLAB，如果像我一樣還是報錯，別慌，繼續安裝codecs(解碼器)

sudo apt install ubuntu-restricted-extra

問題解決