andrioid 圖像&視頻處理

https://stackoverflow.com/questions/13152736/how-to-generate-an-md5-checksum-for-a-file-in-android

https://stackoverflow.com/questions/15158651/generate-a-md5-sum-from-an-android-bitmap-object

2. 視頻

http://writingminds.github.io/ffmpeg-android-java/

縮略圖

https://stackoverflow.com/questions/44109057/get-video-thumbnail-from-uri

視頻縮放

https://trac.ffmpeg.org/wiki/Scaling%20(resizing)%20with%20ffmpeg

問題：

ACTION_GET_CONTENT

沒法獲取文件路徑

ACTION_PICK

能夠，緣由不明

獲取選取視頻路徑：

https://stackoverflow.com/questions/31044591/how-to-select-a-video-from-the-gallery-and-get-its-real-path 

判斷媒體類型：

https://stackoverflow.com/questions/17212471/how-to-determine-that-file-recived-is-image-file-video-file-audio-file

圖像旋轉問題：

https://stackoverflow.com/questions/31925712/android-getting-an-image-from-gallery-comes-rotated

 

action pick 兼容性問題

https://stackoverflow.com/questions/36128077/android-opening-a-file-with-action-get-content-results-into-different-uris

這裏有一個問題就是沒法從uri獲取到文件的絕對路徑，只能獲取到文件名。

直接使用uri替代絕對路徑：

http://www.jianshu.com/p/33bc363290e9