Registrare un file WAV mediante le funzioni esterne del API di PulseAudio

Private Const BUFSIZE As Integer = 1024

Library "libpulse-simple:0.0.4"

Public Struct pa_sample_spec

 formato As Byte
 rate As Integer
 channels As Byte

End Struct

Private Const PA_SAMPLE_S16NE As Integer = 3 ' Signed 16 Bit PCM, little endian (PC) Private Const PA_STREAM_RECORD As Integer = 2

' pa_simple* pa_simple_new (const char * server, const char * name, pa_stream_direction_t dir, const char * dev, const char * stream_name, const pa_sample_spec * ss, const pa_channel_map * map, const pa_buffer_attr * attr, int * error) ' Create a new connection to the server. Private Extern pa_simple_new(server As String, name As String, pa_dir As Integer, dev As String, stream_name As String, sample_spec As Pa_sample_spec, channel_map As Pointer, attr As Pointer, pa_Err As Pointer) As Pointer

' int pa_simple_read (pa_simple * s, void * data, size_t bytes, int * error) ' Read some data from the server. Private Extern pa_simple_read(pa_simple As Pointer, data As Pointer, bytes As Integer, pa_Err As Pointer) As Integer

' void pa_simple_free (pa_simple *s) ' Close and free the connection to the server. Private Extern pa_simple_free(pa_simple As Pointer)

Public Sub Main()

 Dim pass As New Pa_sample_spec
 Dim err, ciclo As Integer
 Dim ps As Pointer
 Dim buf As Byte[]
 Dim fl As File
 Dim dati_audio As String
 Dim s As Short
 

' viene impostato il tipo di campione audio da usare:

   With pass
     .formato = PA_SAMPLE_S16NE
     .rate = 44100
     .channels = 2
   End With
   

' Crea il flusso di registrazione:

   ps = pa_simple_new(Null, Application.Name, PA_STREAM_RECORD, Null, "registrazione", pass, 0, 0, 0)
   If IsNull(ps) Then Error.Raise("Errore alla funzione 'pa_simple_new()' !")
   
   dati_audio = "/tmp/file"
   
   fl = Open dati_audio For Create
   
   ciclo = 100000000 / pass.rate
   
   While ciclo > 0
     
     Dec ciclo

     buf = New Byte[BUFSIZE]
     

' Registra alcuni dati audio:

     err = pa_simple_read(ps, buf.data, buf.Count, 0)
     If err < 0 Then Error.Raise("Errore alla funzione 'pa_simple_read()' !")

     For s = 0 To buf.Max
     Write #fl, buf[s] As Byte
   Next
    
   Wend
crea_file(dati_audio)

Print "chiude" ' Va in Chiusura:

 fl.Close
 pa_simple_free(ps)
 Quit

End

Private Procedure crea_file(tmp As String)

Dim dati As String
Dim i As Integer
 

' Impostiamo il blocco iniziale generico del file WAV:

Dim intesta1 As Byte[] = [82, 73, 70, 70]
Dim intesta2 As Byte[] = [87, 65, 86, 69, 102, 109, 116, 32, 16, 0, 0, 0, 1, 0, 2, 0,
                         &44, &AC, 0, 0, &10, &B1, 2, 0, 4, 0, 16, 0, &64, &61, &74, &61]
 
 dati = File.Load(tmp)
 i = Len(dati) + 36
 

' Imposta il valore dimensionale di 4 byte a partire dal 5° byte del futuro file:

 intesta1.Add(i And &FF)
 intesta1.Add(Shr(i And &FF00&, 8))
 intesta1.Add(Shr(i And &FF0000&, 16))
 intesta1.Add(Shr(i And &FF000000&, 24))
 intesta1.Insert(intesta2)
 i = Len(dati)
 intesta1.Add(i And &FF)
 intesta1.Add(Shr(i And &FF00&, 8))
 intesta1.Add(Shr(i And &FF0000&, 16))
 intesta1.Add(Shr(i And &FF000000&, 24))
 

' Per generare il file WAV finale, eseguibile, uniamo i dati del blocco iniziale ai dati grezzi registrati:

 File.Save("/tmp/FileFINALE.wav", intesta1.ToString(0, intesta1.Count) & dati)

End