Differenze tra le versioni di "Convertire un file OggVorbis in WAV ed estrarne anche informazioni con le funzioni esterne del API di VorbisFile"

Da Gambas-it.org - Wikipedia.
 
(19 versioni intermedie di uno stesso utente non sono mostrate)
Riga 1: Riga 1:
 
La libreria di '''''VorbisFile''''' consente di estrarre informazioni di carattere generale da un file audio ''OggVorbis'' e di convertirlo in un file audio WAV.
 
La libreria di '''''VorbisFile''''' consente di estrarre informazioni di carattere generale da un file audio ''OggVorbis'' e di convertirlo in un file audio WAV.
  
 +
Per poter fruire in Gambas delle risorse del API di ''Ogg Vorbis'' si dovrà utilizzare la libreria condivisa: "''libvorbisfile.so.3.3.8'' ".
  
−
Per poter utilizzare le risorse del API di ''VorbisFile'', bisognerà richiamare la libreria attualmente alla versione: ''libvorbisfile.so.3.3.4''
+
Di seguito mostreremo un semplice codice per convertire un file ''OggVorbis'' (44100 hertz, 16 bit, 2 canali) nel corrispondente file ''WAV''.
−
 
+
Library "libvorbisfile:3.3.8"
−
 
+
−
Vediamo di seguito un esempio di codice.
+
Public Struct vorbis_comment
−
 
+
  user_comments As Pointer
−
Poiché l'uso della libreria esterna ''libvorbisfile'' prevede il richiamo diretto ed indiretto di alcune Strutture, ed al fine di poter gestire dette Strutture esterne in modo assolutamente sicuro, ci serviremo di un'apposita libreria esterna scritta in C, che realizzeremo ''ad hoc'' e che richiameremo all'interno del codice Gambas.
+
  comment_lengths As Pointer
−
La libreria ''ad hoc'' per la [[Gestire_con_sicurezza_le_Strutture_esterne|''sicura'' gestione delle Strutture]] di ''libvorbisfile'' sarà la seguente:
+
  comments As Integer
−
  #include "vorbis/codec.h"
+
  vendor As Pointer
−
  #include "vorbis/vorbisfile.h"
+
End Struct
 +
 +
Public Struct ogg_sync_state
 +
  data As Pointer
 +
  storage As Integer
 +
  fill As Integer
 +
  returned As Integer
 +
  unisynced As Integer
 +
  headerbytes As Integer
 +
  bodybytes As Integer
 +
End Struct
 +
 +
Public Struct ogg_stream_state
 +
  body_data As Pointer
 +
  body_storage As Long
 +
  body_fill As Long
 +
  body_returned As Long
 +
  lacing_vals As Pointer
 +
  granule_vals As Pointer
 +
  lacing_storage As Long
 +
  lacing_fill As Long
 +
  lacing_packet As Long
 +
  lacing_returned As Long
 +
  header[282] As Byte
 +
  header_fill As Integer
 +
  e_o_s As Integer
 +
  b_o_s As Integer
 +
  serialno As Long
 +
  pageno As Long
 +
  packetno As Long
 +
  granulepos As Long
 +
End Struct
 +
 +
Public Struct vorbis_dsp_state
 +
  analysisp As Integer
 +
  vi As Pointer
 +
  pcm As Pointer
 +
  pcmret As Pointer
 +
  pcm_storage As Integer
 +
  pcm_current As Integer
 +
  pcm_returned As Integer
 +
  preextrapolate As Integer
 +
  eofflag As Integer
 +
  lW As Long
 +
  W As Long
 +
  nW As Long
 +
  centerW As Long
 +
  granulepos As Long
 +
  sequence As Long
 +
  glue_bits As Long
 +
  time_bits As Long
 +
  floor_bits As Long
 +
  res_bits As Long
 +
End Struct
 +
 +
  Public Struct oggpack_buffer
 +
  endbyte As Long
 +
  endbit As Integer
 +
  buffer As Pointer
 +
  ptr As Pointer
 +
  storage As Long
 +
  End Struct
 
   
 
   
 +
Public Struct vorbis_block
 +
  pcm As Pointer
 +
  opb As Struct Oggpack_buffer
 +
  lW As Long
 +
  W As Long
 +
  nW As Long
 +
  pcmend As Integer
 +
  mode As Integer
 +
  eofflag As Integer
 +
  granulepos As Long
 +
  sequence As Long
 +
  vd As Pointer
 +
  localstore As Pointer
 +
  localtop As Long
 +
  localalloc As Long
 +
  totaluse As Long
 +
  reap As Pointer
 +
  glue_bits As Long
 +
  time_bits As Long
 +
  floor_bits As Long
 +
  res_bits As Long
 +
  internal As Pointer
 +
End Struct
 
   
 
   
−
  int obt_OggVorbis_File_dim() {
+
  Public Struct ov_callbacks
−
   return sizeof(OggVorbis_File);
+
   fread As Pointer
−
  }
+
  _ov_header_fseek_wrap As Pointer
 +
  void As Pointer
 +
  ftell As Pointer
 +
  End Struct
 
   
 
   
 +
Public Struct OggVorbis_File
 +
  datasource As Pointer
 +
  seekable As Integer
 +
  offset As Long
 +
  end_ As Long
 +
  oy As Struct Ogg_sync_state
 +
  links As Integer
 +
  offsets As Pointer
 +
  dataoffsets As Pointer
 +
  serialnos As Pointer
 +
  pcmlengths As Pointer
 +
  vi As Pointer
 +
  vc As Pointer
 +
  pcm_offset As Long
 +
  ready_state As Integer
 +
  current_serialno As Long
 +
  current_link As Integer
 +
  bittrack As Float
 +
  samptrack As Float
 +
  os As Struct Ogg_stream_state
 +
  vd As Struct Vorbis_dsp_state
 +
  vb As Struct Vorbis_block
 +
  callbacks As Struct Ov_callbacks
 +
End Struct
 
   
 
   
−
  char * obt_comm(vorbis_comment * p) {
+
  Public Struct vorbis_info
−
  return p->vendor;
 
−
}
 
−
Tale codice in linguaggio C in questo esempio verrà posto nella cartella ''Dati'' dell'applicativo Gambas, ed andrà poi trasformato in una libreria condivisa ''.so'' , che - come già accennato - sarà richiamata nel codice Gambas.
 
−
 
 
−
 
 
−
Il codice Gambas dell'applicativo sarà invece il seguente:
 
−
'''Public''' Struct vorbis_info
 
 
   version As Integer
 
   version As Integer
 
   channels As Integer
 
   channels As Integer
 
   rate As Long
 
   rate As Long
−
<FONT color=gray>' ''BITRATE:''
 
−
' ''1) Tutti e tre impostati sullo stesso valore: implica un bitstream a valore fisso.''
 
−
' ''2) Solo il nominale impostato: nessun rigido limite superiore/inferiore.''
 
−
' ''3) Superiore e/o inferiore impostato: implica un flusso di bit VBR che segue i limiti di bitrate.''</font>
 
 
   bitrate_upper As Long
 
   bitrate_upper As Long
 
   bitrate_nominal As Long
 
   bitrate_nominal As Long
 
   bitrate_lower As Long
 
   bitrate_lower As Long
 
   bitrate_window As Long
 
   bitrate_window As Long
−
  '''End''' Struct
+
  End Struct
 +
 
 +
<FONT color=gray>' ''int ov_fopen(const char *path,OggVorbis_File *vf)''
 +
' ''Opens and initialize an OggVorbis_File structure.''</font>
 +
Private Extern ov_fopen(path As String, vf As OggVorbis_File) As Integer
 +
 
 +
<FONT color=gray>' ''ogg_int64_t ov_pcm_total(OggVorbis_File *vf,int i)''
 +
' ''Returns the total pcm samples of the physical bitstream or a specified logical bitstream.''</font>
 +
Private Extern ov_pcm_total(vf As OggVorbis_File, i As Integer) As Long
 
   
 
   
−
   
+
  <FONT color=gray>' ''vorbis_info *ov_info(OggVorbis_File *vf,int link)''
−
  Library "libvorbisfile:3.3.4"
+
  ' ''Returns the vorbis_info struct for the specified bitstream.''</font>
−
   
+
  Private Extern ov_info(vf As OggVorbis_File, linkI As Integer) As Vorbis_info
−
  <FONT color=gray>' ''int ov_fopen(const char *path,OggVorbis_File *vf)''
+
 
−
  ' ''Function used to open and initialize an OggVorbis_File structure. It sets up all the related decoding structure.''</font>
+
  <FONT color=gray>' ''double ov_time_total(OggVorbis_File *vf,int i)''
−
  '''Private''' Extern ov_fopen(path As String, OggVorbis_File As Pointer) As Integer
+
  ' ''Returns the total time in seconds of the physical bitstream or a specified logical bitstream.''</font>
 +
  Private Extern ov_time_total(vf As OggVorbis_File, i As Integer) As Float
 
   
 
   
 
  <FONT color=gray>' ''vorbis_comment *ov_comment(OggVorbis_File *vf,int link)''
 
  <FONT color=gray>' ''vorbis_comment *ov_comment(OggVorbis_File *vf,int link)''
 
  ' ''Returns a pointer to the vorbis_comment struct for the specified bitstream.''</font>
 
  ' ''Returns a pointer to the vorbis_comment struct for the specified bitstream.''</font>
−
  '''Private''' Extern ov_comment(OggVorbis_File As Pointer, lnk As Integer) As Pointer
+
  Private Extern ov_comment(vf As OggVorbis_File, lnk As Integer) As Pointer
 
   
 
   
−
  <FONT color=gray>' ''vorbis_info *ov_info(OggVorbis_File *vf,int link)''
+
  <FONT color=gray>' ''long ov_read(OggVorbis_File *vf, char *buffer, int length, int bigendianp, int word, int sgned, int *bitstream)''
−
  ' ''Returns the vorbis_info struct for the specified bitstream.''</font>
+
  ' ''Decode a Vorbis file within a loop.''</font>
−
  '''Private''' Extern ov_info(OggVorbis_File As Pointer, lnk As Integer) As Vorbis_info
+
  Private Extern ov_read(vf As OggVorbis_File, buffer As Pointer, length As Integer, bigendianp As Integer, word As Integer, sgned As Integer, bitstream As Pointer) As Long
 +
 
 
   
 
   
−
  <FONT color=gray>' ''double ov_time_total(OggVorbis_File *vf,int i)''
+
  Public Sub Main()
−
' ''Returns the total time in seconds of the physical bitstream''</font>
+
 
−
'''Private''' Extern ov_time_total(OggVorbis_File *vf,int link)
+
  Dim vf As New OggVorbis_File
 +
  Dim vi As Vorbis_info
 +
  Dim commenti As Vorbis_comment
 +
  Dim fin As Pointer
 +
  Dim eo, current_section, err, i As Integer
 +
  Dim rit As Long
 +
  Dim datiPCMgrezzi, fileOGG As String
 +
  Dim pcmout As New Byte[](4096)
 +
  Dim fl As File
 +
  Dim b As Byte
 
   
 
   
−
<FONT color=gray>' ''long ov_read(OggVorbis_File *vf,char *buffer,int length, int bigendianp,int word,int sgned,int *bitstream)''
+
  fileOGG = "<FONT color=darkgreen>''/percorso/del/file.ogg''</font>"
−
  ' ''This function makes up the main chunk of a decode loop.''</font>
+
  datiPCMgrezzi = Temp
−
'''Private''' Extern ov_read(OggVorbis_File As Pointer, buf As Byte[], length As Integer, bigendianp As Integer, word As Integer, sgned As Integer, bitstream As Pointer) As Long
+
   
 +
  fl = Open datiPCMgrezzi For Create
 +
   
 +
  err = ov_fopen(fileOGG, vf)
 +
  If err < 0 Then Error.Raise("Il file caricato potrebbe non essere del formato Ogg !")
 +
 
 +
  <FONT color=gray>' ''Estrae alcune informazioni generali del file audio Ogg caricato:''</font>
 +
  vi = ov_info(vf, -1)
 +
 
 +
  Print "File audio:                              "; fileOGG
 +
  With vi
 +
    Print "Frequenza di campionamento:              "; .rate; " Hertz"
 +
    Print "Canali di uscita:                        "; .channels
 +
    Print "Bitrate:                                "; .bitrate_nominal \ 1000; " Kbps"
 +
    Print "Durata del file ogg:                    "; Time(0, 0, 0, ov_time_total(vf, -1) * 1000)
 +
    Print "Lunghezza dei campioni decodificati:    "; ov_pcm_total(vf, -1); " byte"
 +
  End With
 +
  Print "Commenti presenti nel file ogg:"
 +
  With commenti = ov_comment(vf, -1)
 +
    If commenti.comments > 0 Then
 +
      For b = 0 To commenti.comments - 1
 +
        i = 8 * b
 +
        Print "  "; String@(Pointer@(commenti.user_comments + i))
 +
      Next
 +
      Print "  "; String@(commenti.vendor)
 +
    Endif
 +
  End With
 
   
 
   
−
<FONT color=gray>' ''int ov_clear(OggVorbis_File *vf)''
+
  Write "\e[5mAttendere...\e[0m"
−
' ''To clear the decoder's buffers.''</font>
+
  Flush
−
'''Private''' Extern ov_clear(OggVorbis_File As Pointer) As Integer
 
 
   
 
   
 +
<FONT color=gray>' ''Ciclo per la decodifica dei dati Ogg e per la scrittura del file contenente i dati grezzi PCM:''</font>
 +
  While eo = 0
 +
    rit = ov_read(vf, pcmout.Data, pcmout.Count, 0, 2, 1, VarPtr(current_section))
 +
    If rit = 0 Then
 +
      eo = 1
 +
    Else
 +
<FONT color=gray>' ''Scrive il file contenente i dati grezzi PCM:''</font>
 +
      pcmout.Write(fl, 0, rit)
 +
    Endif
 +
  Wend
 
   
 
   
−
<FONT color=gray>' ''Richiamiamo la nostra libreria esterna speciale,
+
  Write "\rConversione terminata !"
−
' ''per la gestione "sicura" della Struttura di VorbisFile:''</font>
 
−
Library "/tmp/libreria_vf"
 
−
'''Private''' Extern obt_OggVorbis_File_dim() As Integer
 
−
'''Private''' Extern obt_Vorbis_Comment_dim() As Integer
 
−
'''Private''' Extern obt_Vorbis_Info_dim() As Integer
 
−
'''Private''' Extern obt_comm(p As Pointer) As Pointer
 
 
   
 
   
 +
<FONT color=gray>' ''Va a creare il file WAV finale:''</font>
 +
  crea_file_wav(datiPCMgrezzi)
 
   
 
   
−
  '''Public''' Sub Main()
+
  <FONT color=gray>' ''Va in chiusura:''</font>
 +
  fl.Close
 
   
 
   
−
  Dim buffer As New Byte[4096]
+
  End
−
  Dim fl As File
 
−
  Dim ovf, commP, vend As Pointer
 
−
  Dim vi As Vorbis_info
 
−
  Dim err, eo, current_section, durata As Integer
 
−
  Dim ret As Long  
 
−
  Dim bh As Byte[] = [&52, &49, &46, &46, &00, &00, &00, &00, &57, &41, &56, &45, &66, &6D, &74, &20, &10, &00, &00, &00, &01, &00, &02, &00,
 
−
                      &44, &AC, &00, &00, &10, &B1, &02, &00, &04, &00, &10, &00, &64, &61, &74, &61, &00, &00, &00, &00]  <FONT color=gray>' ''blocco d'intestazione del file wav futuro: 2 canali, 16 bit, hz 44100''</font>
 
 
   
 
   
 
   
 
   
−
  <FONT color=gray>' ''Se non è presente la libreria "ad hoc" da noi realizzata, allora la crea:''</font>
+
  Private Procedure crea_file_wav(datiGrezzi As String)
−
  If Exist("/tmp/libreria_vf.so") = False Then creaVf()
 
 
    
 
    
−
<FONT color=gray>' ''Genera ed apre il futuro file wav:''</font>
+
  Dim fl, fwav As File
−
  fl = Open "/tmp/fileWAV.wav" For Create
+
  Dim i, i2 As Integer
−
+
  Dim dati As New Byte[](Stat(datiGrezzi).Size)
−
  ovf = Alloc(obt_OggVorbis_File_dim())
+
  Dim bh As Byte[] = [&52, &49, &46, &46, &00, &00, &00, &00, &57, &41, &56, &45, &66, &6D, &74, &20, &10, &00, &00, &00, &01, &00, &02, &00,
−
    
+
                    &44, &AC, &00, &00, &10, &B1, &02, &00, &04, &00, &10, &00, &64, &61, &74, &61, &00, &00, &00, &00]    <FONT color=gray>' ''blocco d'intestazione del file wav futuro: 2 canali, 16 bit, hz 44100''</font>
−
  err = ov_fopen("''/percorso/del/file.ogg''", ovf)
+
                   
−
  If err <> 0 Then Error.Raise("Errore nell'apertura del file audio !")
+
  fl = Open datiGrezzi For Read
 +
  dati.Read(fl)
 +
     
 +
   i = Lof(fl)
 +
  fl.Close
 +
  i2 = i + 36
 
    
 
    
 +
<FONT color=gray>' ''Imposta il valore dimensionale di 4 byte a partire dal 5° byte del futuro file wav:''</font>
 +
  bh[4] = i2 And &FF
 +
  bh[5] = Shr(i2 And &FF00&, 8)
 +
  bh[6] = Shr(i2 And &FF0000&, 16)
 +
  bh[7] = Shr(i2 And &FF000000&, 24)
 
   
 
   
−
  vi = ov_info(ovf, -1)
+
<FONT color=gray>' ''Imposta il valore dimensionale di 4 byte a partire dal 41° byte del futuro file wav.''
 +
' ''Esso è relativo alla quantità effettiva dei dati audio grezzi.''</font>
 +
  bh[40] = i And &FF
 +
  bh[41] = Shr(i And &FF00&, 8)
 +
  bh[42] = Shr(i And &FF0000&, 16)
 +
  bh[43] = Shr(i And &FF000000&, 24)
 
   
 
   
−
  With vi
+
  bh.Insert(dati, 44)
−
    Print "Frequenza di campionamento: hz "; .rate
 
−
    Print "Canali d'uscita: "; .channels
 
−
    If .bitrate_lower > 0 Then Print "Bitrate inferiore: "; .bitrate_lower
 
−
    If .bitrate_nominal > 0 Then Print "Bitrate nominale: "; .bitrate_nominal
 
−
    If .bitrate_upper > 0 Then Print "Bitrate superiore: "; .bitrate_upper
 
−
  End With
 
 
   
 
   
−
  durata = Fix(ov_time_total(ovf, -1) * 1000)
+
  fwav = Open "<FONT color=darkgreen>''/percorso/del/file.wav''</font>" For Create
−
  Print "Durata del brano: "; Date(0, 0, 0, 0, 0, 0, durata)
 
−
   
 
−
   
 
−
  commP = ov_comment(ovf, -1)
 
−
  vend = obt_comm(commP)
 
−
  Print "Codificato con "; String@(vend)
 
−
   
 
 
   
 
   
 
  <FONT color=gray>' ''Inizia la scrittura del file wav:''</font>
 
  <FONT color=gray>' ''Inizia la scrittura del file wav:''</font>
−
  bh.Write(fl, 0, bh.Count)
+
  bh.Write(fwav, 0, bh.Count)
−
 
−
  While eo = 0
 
−
    ret = ov_read(ovf, buffer, 4096, 0, 2, 1, VarPtr(current_section))
 
−
     
 
−
    If ret = 0 Then
 
−
      eo = 1      ' Eof
 
−
    Else If ret < 0 Then
 
−
      Error.Raise("Errore nella lettura dei dati audio del file !")
 
−
    Else
 
−
      buffer.Write(fl, 0, ret)
 
−
    Endif
 
−
    Wend
 
−
 
−
 
−
<FONT color=gray>' ''Va in chiusura:''</font>
 
−
  fl.Close
 
−
  ov_clear(ovf)
 
−
  Free(ovf)
 
−
 
−
'''End'''
 
−
 
 
   
 
   
−
<FONT color=gray>' ''Crea l'apposita libreria per la gestione sicura delle Strutture di 'libvorbisfile':''</font>
+
  Print "\n\nDurata del file WAV: "; Time(0, 0, 0, ((i * 8) / (44100 * 16 * 2)) * 1000)
−
'''Private''' Procedure creaVf()
 
 
   
 
   
−
  Shell "gcc -o /tmp/libreria_vf.so " & Application.Path &/ "libreria_vf.c -shared -fPIC" Wait
+
  dati.Clear
 +
  bh.Clear
 +
  fl.Close
 +
  fwav.Close
 
   
 
   
−
  '''End'''
+
  End
  
  
  
 
=Riferimenti=
 
=Riferimenti=
−
[1] [http://www.xiph.org/vorbis/doc/vorbisfile/index.html Vorbisfile Documentation]
+
* http://www.xiph.org/vorbis/doc/
 +
* http://www.vorbis.com/setup_linux/

Versione attuale delle 05:28, 14 gen 2024

La libreria di VorbisFile consente di estrarre informazioni di carattere generale da un file audio OggVorbis e di convertirlo in un file audio WAV.

Per poter fruire in Gambas delle risorse del API di Ogg Vorbis si dovrà utilizzare la libreria condivisa: "libvorbisfile.so.3.3.8 ".

Di seguito mostreremo un semplice codice per convertire un file OggVorbis (44100 hertz, 16 bit, 2 canali) nel corrispondente file WAV. 

Library "libvorbisfile:3.3.8"

Public Struct vorbis_comment
  user_comments As Pointer
  comment_lengths As Pointer
  comments As Integer
  vendor As Pointer
End Struct

Public Struct ogg_sync_state
  data As Pointer
  storage As Integer
  fill As Integer
  returned As Integer
  unisynced As Integer
  headerbytes As Integer
  bodybytes As Integer
End Struct

Public Struct ogg_stream_state
  body_data As Pointer
  body_storage As Long
  body_fill As Long
  body_returned As Long
  lacing_vals As Pointer
  granule_vals As Pointer
  lacing_storage As Long
  lacing_fill As Long
  lacing_packet As Long
  lacing_returned As Long
  header[282] As Byte
  header_fill As Integer
  e_o_s As Integer
  b_o_s As Integer
  serialno As Long
  pageno As Long
  packetno As Long
  granulepos As Long
End Struct

Public Struct vorbis_dsp_state
  analysisp As Integer
  vi As Pointer
  pcm As Pointer
  pcmret As Pointer
  pcm_storage As Integer
  pcm_current As Integer
  pcm_returned As Integer
  preextrapolate As Integer
  eofflag As Integer
  lW As Long
  W As Long
  nW As Long
  centerW As Long
  granulepos As Long
  sequence As Long
  glue_bits As Long
  time_bits As Long
  floor_bits As Long
  res_bits As Long
End Struct

Public Struct oggpack_buffer
  endbyte As Long
  endbit As Integer
  buffer As Pointer
  ptr As Pointer
  storage As Long
End Struct

Public Struct vorbis_block
  pcm As Pointer
  opb As Struct Oggpack_buffer
  lW As Long
  W As Long
  nW As Long
  pcmend As Integer
  mode As Integer
  eofflag As Integer
  granulepos As Long
  sequence As Long
  vd As Pointer
  localstore As Pointer
  localtop As Long
  localalloc As Long
  totaluse As Long
  reap As Pointer
  glue_bits As Long
  time_bits As Long
  floor_bits As Long
  res_bits As Long
  internal As Pointer
End Struct

Public Struct ov_callbacks
  fread As Pointer
  _ov_header_fseek_wrap As Pointer
  void As Pointer
  ftell As Pointer
End Struct

Public Struct OggVorbis_File
  datasource As Pointer
  seekable As Integer
  offset As Long
  end_ As Long
  oy As Struct Ogg_sync_state
  links As Integer
  offsets As Pointer
  dataoffsets As Pointer
  serialnos As Pointer
  pcmlengths As Pointer
  vi As Pointer
  vc As Pointer
  pcm_offset As Long
  ready_state As Integer
  current_serialno As Long
  current_link As Integer
  bittrack As Float
  samptrack As Float
  os As Struct Ogg_stream_state
  vd As Struct Vorbis_dsp_state
  vb As Struct Vorbis_block
  callbacks As Struct Ov_callbacks
End Struct

Public Struct vorbis_info
  version As Integer
  channels As Integer
  rate As Long
  bitrate_upper As Long
  bitrate_nominal As Long
  bitrate_lower As Long
  bitrate_window As Long
End Struct
 
' int ov_fopen(const char *path,OggVorbis_File *vf)
' Opens and initialize an OggVorbis_File structure.
Private Extern ov_fopen(path As String, vf As OggVorbis_File) As Integer
 
' ogg_int64_t ov_pcm_total(OggVorbis_File *vf,int i)
' Returns the total pcm samples of the physical bitstream or a specified logical bitstream.
Private Extern ov_pcm_total(vf As OggVorbis_File, i As Integer) As Long

' vorbis_info *ov_info(OggVorbis_File *vf,int link)
' Returns the vorbis_info struct for the specified bitstream.
Private Extern ov_info(vf As OggVorbis_File, linkI As Integer) As Vorbis_info
  
' double ov_time_total(OggVorbis_File *vf,int i)
' Returns the total time in seconds of the physical bitstream or a specified logical bitstream.
Private Extern ov_time_total(vf As OggVorbis_File, i As Integer) As Float

' vorbis_comment *ov_comment(OggVorbis_File *vf,int link)
' Returns a pointer to the vorbis_comment struct for the specified bitstream.
Private Extern ov_comment(vf As OggVorbis_File, lnk As Integer) As Pointer

' long ov_read(OggVorbis_File *vf, char *buffer, int length, int bigendianp, int word, int sgned, int *bitstream)
' Decode a Vorbis file within a loop.
Private Extern ov_read(vf As OggVorbis_File, buffer As Pointer, length As Integer, bigendianp As Integer, word As Integer, sgned As Integer, bitstream As Pointer) As Long
  

Public Sub Main()
 
 Dim vf As New OggVorbis_File
 Dim vi As Vorbis_info
 Dim commenti As Vorbis_comment
 Dim fin As Pointer
 Dim eo, current_section, err, i As Integer
 Dim rit As Long
 Dim datiPCMgrezzi, fileOGG As String
 Dim pcmout As New Byte[](4096)
 Dim fl As File
 Dim b As Byte

 fileOGG = "/percorso/del/file.ogg"
 datiPCMgrezzi = Temp
   
 fl = Open datiPCMgrezzi For Create
    
 err = ov_fopen(fileOGG, vf)
 If err < 0 Then Error.Raise("Il file caricato potrebbe non essere del formato Ogg !")
  
' Estrae alcune informazioni generali del file audio Ogg caricato:
 vi = ov_info(vf, -1)
 
 Print "File audio:                              "; fileOGG
 With vi
   Print "Frequenza di campionamento:              "; .rate; " Hertz"
   Print "Canali di uscita:                        "; .channels
   Print "Bitrate:                                 "; .bitrate_nominal \ 1000; " Kbps"
   Print "Durata del file ogg:                     "; Time(0, 0, 0, ov_time_total(vf, -1) * 1000)
   Print "Lunghezza dei campioni decodificati:     "; ov_pcm_total(vf, -1); " byte"
 End With
 Print "Commenti presenti nel file ogg:"
 With commenti = ov_comment(vf, -1)
   If commenti.comments > 0 Then
     For b = 0 To commenti.comments - 1
       i = 8 * b
       Print "   "; String@(Pointer@(commenti.user_comments + i))
     Next
     Print "   "; String@(commenti.vendor)
   Endif 
 End With

 Write "\e[5mAttendere...\e[0m"
 Flush

' Ciclo per la decodifica dei dati Ogg e per la scrittura del file contenente i dati grezzi PCM:
 While eo = 0
   rit = ov_read(vf, pcmout.Data, pcmout.Count, 0, 2, 1, VarPtr(current_section))
   If rit = 0 Then
     eo = 1
   Else
' Scrive il file contenente i dati grezzi PCM:
     pcmout.Write(fl, 0, rit)
   Endif
 Wend

 Write "\rConversione terminata !"

' Va a creare il file WAV finale:
 crea_file_wav(datiPCMgrezzi)

' Va in chiusura:
 fl.Close

End


Private Procedure crea_file_wav(datiGrezzi As String)
 
 Dim fl, fwav As File
 Dim i, i2 As Integer
 Dim dati As New Byte[](Stat(datiGrezzi).Size)
 Dim bh As Byte[] = [&52, &49, &46, &46, &00, &00, &00, &00, &57, &41, &56, &45, &66, &6D, &74, &20, &10, &00, &00, &00, &01, &00, &02, &00,
                    &44, &AC, &00, &00, &10, &B1, &02, &00, &04, &00, &10, &00, &64, &61, &74, &61, &00, &00, &00, &00]    ' blocco d'intestazione del file wav futuro: 2 canali, 16 bit, hz 44100
                    
 fl = Open datiGrezzi For Read
 dati.Read(fl)
     
 i = Lof(fl)
 fl.Close
 i2 = i + 36
 
' Imposta il valore dimensionale di 4 byte a partire dal 5° byte del futuro file wav:
 bh[4] = i2 And &FF
 bh[5] = Shr(i2 And &FF00&, 8)
 bh[6] = Shr(i2 And &FF0000&, 16)
 bh[7] = Shr(i2 And &FF000000&, 24)

' Imposta il valore dimensionale di 4 byte a partire dal 41° byte del futuro file wav.
' Esso è relativo alla quantità effettiva dei dati audio grezzi.
 bh[40] = i And &FF
 bh[41] = Shr(i And &FF00&, 8)
 bh[42] = Shr(i And &FF0000&, 16)
 bh[43] = Shr(i And &FF000000&, 24)

 bh.Insert(dati, 44)

 fwav = Open "/percorso/del/file.wav" For Create

' Inizia la scrittura del file wav:
 bh.Write(fwav, 0, bh.Count)

 Print "\n\nDurata del file WAV: "; Time(0, 0, 0, ((i * 8) / (44100 * 16 * 2)) * 1000)

 dati.Clear
 bh.Clear
 fl.Close
 fwav.Close

End


Riferimenti

Estratto da "https://www.gambas-it.org/wiki/index.php?title=Convertire_un_file_OggVorbis_in_WAV_ed_estrarne_anche_informazioni_con_le_funzioni_esterne_del_API_di_VorbisFile&oldid=36223"