1. errCode: 601
2. errDesc: "audio export failed"
3. errMsg: "operateMediaContainer:fail errType: 1, errCode: 601, errMsg: audio export failed"
4. 
   
5. dd
6. 代码如下：

                    var mc = wx.createMediaContainer();

                    mc.extractDataSource({

                        source: tempFilePath,

                        success: (obj) => {

                            console.log(obj)

                            const audioTrack = obj.tracks[0];

                            mc.addTrack(audioTrack); // 将视频轨道加入到待合成

                            // 导出合成容器中的音频

                            mc.export({

                                success: (x) => {

                                    // 拿到导出之后的音频

                                    console.log("导出音频：", x.tempFilePath);

                                    mc.destroy();

                                },

                                fail: (x) => {

                                    console.log(x)

                                    console.log("导出失败");

                                    mc.destroy();

                                }

                            });

                        },

                    });