Convertire un file OggVorbis in WAV ed estrarne anche informazioni con le funzioni esterne del API di VorbisFile
Da Gambas-it.org - Wikipedia.
Versione del 4 ott 2022 alle 05:15 di Vuott (Discussione | contributi)
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.3.3.7 "
Di seguito mostreremo un semplice codice per convertire un file OggVorbis (44100 hertz, 16 bit, 2 canali) nel corrispondente file WAV.
Library "libvorbisfile:3.3.7"
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
