如何在Golang中格式化持续时间

I have the following code which I can't run on play because I use the gin framework and filewalk.

package main

import (
    "fmt"
    "os"
    "path/filepath"
    "time"
    "regexp"
    "github.com/gin-gonic/gin"
    "sort"
    "strings"
    "github.com/davidscholberg/go-durationfmt"
)

var filext = regexp.MustCompile(`\.[mM][pP]4|\.[mM]4[vV]|\.jpg|\.[hH]264|\.go`)
var m map[int]string
var keys []int

func main() {

    if gin.IsDebugging() {
        fmt.Print("This progamm shows only the path and the age of a file in 'STARTDIR'
")
        fmt.Print("only the following files will be handled '.[mM][pP]4|.[mM]4[vV$|.[hH]264|.go'
")
        fmt.Print("The git repository: https://gitlab.com/aleks001/show-files-age 
")
    }

    if len(os.Getenv("LISTEN_IP_PORT")) == 0 {
        fmt.Print("I need a ip and port on which I should listen.
")
        os.Exit(1)
    }
    router := gin.Default()

    gin.DisableConsoleColor()

    router.GET("/videoinfo",getInfo)

    router.Run(os.Getenv("LISTEN_IP_PORT"))
}

func getInfo(c *gin.Context)  {

    loc, _ := time.LoadLocation("Europe/Vienna")
    var startdir = ""

    if os.Getenv("STARTDIR") != "" {
        startdir = os.Getenv("STARTDIR")
    } else if c.GetHeader("STARTDIR") != "" {
        startdir = c.GetHeader("STARTDIR")
    } else {
        c.String(404,"Startdir not found <br>
")
        return
    }

    m = make(map[int]string)
    keys = nil

    filepath.Walk(startdir,walkpath)

    for k := range m {
        keys = append(keys, k)
    }
    sort.Ints(keys)

    for _, k := range keys {
        t := time.Date(time.Now().Year(),time.Now().Month(),time.Now().Day(),time.Now().Hour(),k,time.Now().Second(),time.Now().Nanosecond(),loc)
        durStr, err := durationfmt.Format(time.Since(t), "%h:%m")

        if err != nil {
            fmt.Println(err)
        } else {
            //fmt.Println(durStr)
            fmt.Printf("Key: %s Value: %s
", durStr , m[k])
            c.String(200,"Minutes: %s File: %s
", durStr, m[k])
        }
    }
}

func walkpath(path string, f os.FileInfo, err error) error {

  if err != nil {
        fmt.Println(err)
    } else {
        if filext.MatchString(path) {
            age := time.Now().Sub(f.ModTime())
            path_new := strings.Replace(path,"/videos/","",1)
            // path_new := strings.Replace(path,"..\\","",1)
            /*
            fmt.Printf("Path: %s, ModTime: %s, Age: %s <br>
", walker.Path(), walker.Stat().ModTime(), age)
            c.String(200,"Path: %s, ModTime: %s, Age: %s <br>
", walker.Path(), walker.Stat().ModTime(), age)
            */
            fmt.Printf("Path: %s, Age: %d age minutes %0.2f  <br>
", path_new, age, age.Minutes())
            m[int(age.Minutes())]=path_new
            //c.String(200,"Path: %s, Age: %0.2f <br>
", path, age.Minutes())
        }
    //fmt.Printf("%s with %d bytes at motime %s
", path,f.Size(), f.ModTime())
}
    return nil
}

filext

I was able to fulfil the most part of the request but the output looks ugly as you can see below.

I have used https://github.com/davidscholberg/go-durationfmt to format the duration but the output looks ugly or I missus the library.

Minutes: 0:6 File: upload/dir003/file1.m4v
Minutes: 0:5 File: transfer/dir5/file2.jpg
Minutes: -5:-48 File: transfer/dir001/file.mp4
Minutes: -6:-21 File: transfer/03.jpg
Minutes: -6:-22 File: transfer/02.mp4

As I'm very new to go I'm sure that there are better way to solve this issue. Thanks for help.