只要会了以上的方法, 倒退播放和快速播放就非常简单了, 如下:
1. 场景上建立两个按钮, 分别为(倒退 rev 和 快速播放 ff)
2. 在第一帧使用以下代码 :

          mySound = new Sound();
          mySound.attachSound("tomato");
          mySound.start();
          var SecondsOffset = 0;
          var reverse = foward = false;       //设定倒退和前进变量为false
          onEnterFrame = function () {
                      if (reverse && mySound.position > 0) {       //当倒退按下且音乐秒数大于0
                                mySound.stop();       //音乐停止
                                  SecondsOffset -= .5;    //offset倒退0.5秒
                                  mySound.start(SecondsOffset, 0);       //音乐从倒退的0.5秒开始播放
                      }
                      if (foward && mySound.position <= mySound.duration) {       //当快速播放按下且音乐不为结束
                                    mySound.stop();
                                  SecondsOffset += .5;       //offset前进0.5秒
                                  mySound.start(SecondsOffset, 0);
                      }
                      rev.onPress = function() {       //当倒退按下并取得position
                                  SecondsOffset = mySound.position/1000;
                                  reverse = true;       //reverse变量为true
                      };
                      rev.onRelease = function() {       //当倒退放开就设定reverse变量为false
                                    reverse = false;
                      }
                      ff.onPress = function() {       //同上
                                  SecondsOffset = mySound.position/1000;
                                  foward = true;
                      };
                      ff.onRelease = function() {
                                  foward = false;
                        }
          };