Update readme

README-EN.md

@@ -31,6 +31,7 @@ Before using library, you can star and download the code to try the example.
       - [get media info](#get-media-info)
       - [screen shot](#screen-shot)
       - [Observer for resource](#observer-for-resource)
+      - [Media Speed](#media-speed)
       - [IjkStatus](#ijkstatus)
       - [Custom Options](#custom-options)
         - [IjkOptionCategory](#ijkoptioncategory)
@@ -264,6 +265,22 @@ Stream<IjkStatus> ijkStatusStream = controller.ijkStatusStream;
 
 ```
 
+#### Media Speed
+
+code:
+
+```dart
+controller.setSpeed(2.0);
+```
+
+Default speed is 1.0, the min value need bigger than 0
+
+Because of the speed change, the tone will change. So you need to use an option to keep the tone unchanged. The option **default value is open**, and if you want to close it, use the code:
+
+```dart
+IjkMediaController(needChangeSpeed: false); // set needChangeSpeed to false, the tone will change on speed change.
+```
+
 #### IjkStatus
 
 | name              | describe                                                       |

README.md

@@ -36,6 +36,7 @@ android 模拟器 mac android sdk 自带的 emulator(API28 android9)可用,其
       - [获取播放信息](#%E8%8E%B7%E5%8F%96%E6%92%AD%E6%94%BE%E4%BF%A1%E6%81%AF)
       - [截取视频帧](#%E6%88%AA%E5%8F%96%E8%A7%86%E9%A2%91%E5%B8%A7)
       - [资源监听](#%E8%B5%84%E6%BA%90%E7%9B%91%E5%90%AC)
+      - [倍速播放](#%E5%80%8D%E9%80%9F%E6%92%AD%E6%94%BE)
       - [IjkStatus 说明](#ijkstatus-%E8%AF%B4%E6%98%8E)
       - [自定义 Option](#%E8%87%AA%E5%AE%9A%E4%B9%89-option)
         - [IjkOptionCategory](#ijkoptioncategory)
@@ -291,6 +292,23 @@ Stream<bool> volumeStream = controller.playingStream;
 Stream<IjkStatus> ijkStatusStream = controller.ijkStatusStream;
 ```
 
+#### 倍速播放
+
+调用代码:
+
+```dart
+controller.setSpeed(2.0);
+```
+
+支持的倍率默认为 1.0, 上限不明,下限请不要小于等于 0,否则可能会 crash
+
+变调的问题:
+由于变速变调的问题, 如果需要不变调, 需要一个 option 的支持, 这个 option **默认开启**, 如果要关闭这个, 可以使用如下代码
+
+```dart
+IjkMediaController(needChangeSpeed: false); // 这个设置为false后, 则变速时会声音会变调的情况发生
+```
+
 #### IjkStatus 说明
 
 | 名称              | 说明                     |