uniapp开发微信小程序保存视频到相册40MB左右的视频无法保存

保存10MB-20MB左右的视频 都没问题，有一个40MB的视频，一直保存不下来呢？
下面是保存视频的代码

uni.downloadFile({  
                        url: this.fileOpt.filePath, //你的视频地址  
                        header: {"Content-Type":"video/mp4"},  
                        success:function(res){  
                            console.log('视频下载成功', res)  
                            utils.hideLoading();  
                            //保存视频到相册  
                            uni.saveVideoToPhotosAlbum({  
                                filePath: res.tempFilePath,  
                                success: function(data) {  
                                    uni.hideLoading()  
                                    uni.showModal({  
                                        title: '提示',  
                                        content: '已保存到相册',  
                                        showCancel: false,  
                                    })  
                                },  
                                fail: function(err) {  
                                    console.log("save video error", err)  
                                    if (err.errMsg === "saveVideoToPhotosAlbum:fail:auth denied" ||  
                                        err  
                                        .errMsg === "saveVideoToPhotosAlbum:fail auth deny" || err  
                                        .errMsg ===  
                                        "saveVideoToPhotosAlbum:fail authorize no response"  
                                    ) {  
                                        // 这边微信做过调整，必须要在按钮中触发，因此需要在弹框回调中进行调用  
                                        uni.showModal({  
                                            title: '提示',  
                                            content: '需要您授权保存相册',  
                                            showCancel: false,  
                                            success: modalSuccess => {  
                                                uni.openSetting({  
                                                    success(settingdata) {  
                                                        console.log(  
                                                            "settingdata",  
                                                            settingdata)  
                                                        if (settingdata  
                                                            .authSetting[  
                                                                'scope.writePhotosAlbum'  
                                                            ]) {  
                                                            uni.showModal({  
                                                                title: '提示',  
                                                                content: '获取权限成功,再次保存即可',  
                                                                showCancel: false,  
                                                            })  
                                                        } else {  
                                                            uni.showModal({  
                                                                title: '提示',  
                                                                content: '获取权限失败，将无法保存到相册',  
                                                                showCancel: false,  
                                                            })  
                                                        }  
                                                    },  
                                                    fail(failData) {  
                                                        console.log("failData",  
                                                            failData)  
                                                    },  
                                                    complete(finishData) {  
                                                        console.log(  
                                                            "finishData",  
                                                            finishData)  
                                                    }  
                                                })  
                                            }  
                                        })  
                                    } else {  
                                        uni.showModal({  
                                            title: '提示',  
                                            content: '保存失败',  
                                            showCancel: false,  
                                        })  
                                    }  
                                },  
                                complete(res) {  
                                    uni.hideLoading()  
                                }  
                            })  
                        }  
                })