andrioid 图像&视频处理

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. 视频

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

缩略图

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

视频缩放

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

问题：

ACTION_GET_CONTENT

没法获取文件路径

ACTION_PICK

能够，缘由不明

获取选取视频路径：

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

判断媒体类型：

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

图像旋转问题：

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

 

action pick 兼容性问题

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

这里有一个问题就是没法从uri获取到文件的绝对路径，只能获取到文件名。

直接使用uri替代绝对路径：

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