Conoscere la durata di un file Midi mediante le funzioni esterne del API di Libsmf

La libreria Libsmf, ideata per la gestione degli standard Midi File, consente, fra l'altro, di conoscere la durata in secondi di un file Midi.

E' necessario aver installata e richiamare la libreria condivisa: "libsmf:0.0.0 ".

Mostriamo un semplice esempio:

Library "libsmf:0.0.0"

Public Struct smf_struct
  formati As Integer
  ppqn As Integer
  frames_per_second As Integer
  resolution As Integer
  number_of_tracks As Integer
  streamf As Pointer
  file_buffer As Pointer
  file_buffer_length As Integer
  next_chunk_offset As Integer
  expected_number_of_tracks As Integer
  tracks_array As Pointer
  last_seek_position As Float
  tempo_array As Pointer
End Struct

' smf_t* smf_load (const char * file_name)
' Loads SMF file.
Private Extern smf_load(file_name As String) As Pointer

' double smf_get_length_seconds (const smf_t * smf)
' Length of SMF, in seconds.
Private Extern smf_get_length_seconds(smf_t As Smf_struct) As Float

' void smf_delete (smf_t *smf)
' Frees smf and all it's descendant structures.
Private Extern smf_delete(smf As Smf_struct)


Public Sub Main()

 Dim smf As smf_struct
 Dim durata As Float
 
  smf = smf_load("/percorso/del/file.mid")
   
  durata = smf_get_length_seconds(smf)
   
  smf_delete(smf)
  
  Print "Durata del file Midi: "; Time(0, 0, 0, durata * 1000)

End

Riferimenti

• http://libsmf.sourceforge.net/api/