MP3 file information parsing using Go and libmpg123

main.go

package main

import "mp3"
import "os"

func main() {
  mp3.PrintInfo(os.Args[1])
}

music.go

package mp3

// #cgo LDFLAGS: -lmpg123
/*
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <errno.h>
#include "mpg123.h"

*/
import "C"

import (
  "fmt"
)

func PrintInfo(file string) {

  var v1 *C.mpg123_id3v1
  var v2 *C.mpg123_id3v2

  C.mpg123_init()
  defer C.mpg123_exit()

  m := C.mpg123_new(nil, nil)
  defer C.mpg123_delete(m)

  f := C.CString(file)

  if err := C.mpg123_open(m, f); err != C.MPG123_OK {
    panic("Error reading file")
  }
  defer C.mpg123_close(m)

  C.mpg123_scan(m)
  meta := C.mpg123_meta_check(m)

  if meta == C.MPG123_ID3 && C.mpg123_id3(m, &v1, &v2) == C.MPG123_OK {
    var title, artist, album, genre string
    switch false {
    case v2 == nil:
      fmt.Println("ID3V2 tag found")
      title = C.GoString(v2.title.p)
      artist = C.GoString(v2.artist.p)
      album = C.GoString(v2.album.p)
      genre = C.GoString(v2.genre.p)

    case v1 == nil:
      fmt.Println("ID3V1 tag found")
      title = C.GoString(&v1.title[0])
      artist = C.GoString(&v1.artist[0])
      album = C.GoString(&v1.album[0])
      genre = "Unknown" // FIXME convert int to string				
    }

    fmt.Println(title)
    fmt.Println(artist)
    fmt.Println(album)
    fmt.Println(genre)
  }
}