Add open-source lib of multimedia

README.md

@@ -14,6 +14,9 @@
 ### 音视频进阶成长:
 ![preview](https://github.com/xufuji456/FFmpegAndroid/blob/master/picture/multimedia_main.png)
 
+### 音视频开源库:
+![preview](https://github.com/xufuji456/FFmpegAndroid/blob/master/picture/multimedia_library.png)
+
 ### Joining the group to learn FFmpeg:
 ![preview](https://github.com/xufuji456/FFmpegAndroid/blob/master/picture/ffmpeg_group.png)