Estrarre in formato testuale i dati di un file Midi con le funzioni esterne del API di Libsmf
Da Gambas-it.org - Wikipedia.
La libreria Libsmf consente di gestire i file Midi.
Per poter fruire nei programmi Gambas le sue risorse, è necessario installare e richiamare la libreria condivisa: "libsmf:0.0.0 ".
Mostriamo di seguito un semplice esempio per ottenere in formato testuale gli eventi Midi presenti in uno standard Midi file:
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 Smf_struct
' smf_event_t * smf_get_next_event (smf_t * smf)
' Next event, in time order, or NULL, if there are none left.
Private Extern smf_get_next_event(smf_t As Smf_struct) As Pointer
' char * smf_event_decode (const smf_event_t * event)
' Textual representation of the event given, or NULL, if event is unknown.
Private Extern smf_event_decode(smf_event As Pointer) As String
' 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 evento As Pointer
smf = smf_load("/percorso/del/file.mid")
evento = smf_get_next_event(smf)
If evento == 0 Then Error.Raise("Errore !")
While evento > 0
Print smf_event_decode(evento)
evento = smf_get_next_event(smf)
Wend
smf_delete(smf)
End
