c# 调用 ffmpeg 获取音频时长

                    var arg = "-i \"" + filepath + "\" 2";
                    TimeSpan duration = TimeSpan.Zero;
                    await FFMpeg.Xamarin.FFmpegLibrary.Run(this.BaseContext, arg, (line) =>
                    {
                        System.Diagnostics.Debug.WriteLine("ffmpeg output:" + line);
                        var regex = new Regex(@"Duration: (\d+):(\d\d):(\d\d)\.(\d+)");
                        var match = regex.Match(line);
                        if (match.Success)
                        {
                            var hours = int.Parse(match.Groups[1].Value);
                            var minutes = int.Parse(match.Groups[2].Value);
                            var seconds = int.Parse(match.Groups[3].Value);
                            var milliseconds = int.Parse(match.Groups[4].Value) * 10;
                            duration = new TimeSpan(0, hours, minutes, seconds, milliseconds);
                        }
                    });