Differenze tra le versioni di "Alsa e Gambas: Invio dei dati senza connessione della porta del programma con il Softsynth"
Da Gambas-it.org - Wikipedia.
Riga 190: | Riga 190: | ||
End Struct | End Struct | ||
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Library "libasound:2" | Library "libasound:2" | ||
Private SND_SEQ_OPEN_OUTPUT As Integer = 1 | Private SND_SEQ_OPEN_OUTPUT As Integer = 1 | ||
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Private SND_SEQ_QUEUE_DIRECT As Byte = 253 | Private SND_SEQ_QUEUE_DIRECT As Byte = 253 | ||
Private Enum SND_SEQ_EVENT_NOTEON = 6, SND_SEQ_EVENT_NOTEOFF, SND_SEQ_EVENT_KEYPRESS, SND_SEQ_EVENT_CONTROLLER = 10, SND_SEQ_EVENT_PGMCHANGE | Private Enum SND_SEQ_EVENT_NOTEON = 6, SND_SEQ_EVENT_NOTEOFF, SND_SEQ_EVENT_KEYPRESS, SND_SEQ_EVENT_CONTROLLER = 10, SND_SEQ_EVENT_PGMCHANGE | ||
− | + | ||
− | |||
<FONT Color=gray>' ''int snd_seq_open (snd_seq_t **handle, const char * name, int streams, int mode)'' | <FONT Color=gray>' ''int snd_seq_open (snd_seq_t **handle, const char * name, int streams, int mode)'' | ||
' ''Open the ALSA sequencer.''</font> | ' ''Open the ALSA sequencer.''</font> | ||
Riga 211: | Riga 204: | ||
' ''Returns the message for an error code.''</font> | ' ''Returns the message for an error code.''</font> | ||
Private Extern snd_strerror(err As Integer) As Pointer | Private Extern snd_strerror(err As Integer) As Pointer | ||
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<FONT Color=gray>' ''int snd_seq_event_output (snd_seq_t *handle, snd_seq_event_t *ev) | <FONT Color=gray>' ''int snd_seq_event_output (snd_seq_t *handle, snd_seq_event_t *ev) | ||
' ''Output an event.''</font> | ' ''Output an event.''</font> | ||
Riga 231: | Riga 220: | ||
'''Public''' Sub Main() | '''Public''' Sub Main() | ||
+ | Dim sndseq As Pointer | ||
Dim note As Byte[] = [60, 62, 64, 65, 67, 69, 71, 72] | Dim note As Byte[] = [60, 62, 64, 65, 67, 69, 71, 72] | ||
− | Dim | + | Dim b As Byte |
− | Dim | + | Dim evento As New Snd_seq_event_t |
− | + | sndseq = Connessione() | |
− | With | + | With evento |
<FONT Color=#B22222>.queue = SND_SEQ_QUEUE_DIRECT</font> | <FONT Color=#B22222>.queue = SND_SEQ_QUEUE_DIRECT</font> | ||
− | + | <FONT Color=#B22222>.dest_client = 128</font> | |
− | + | <FONT Color=#B22222>.dest_port = 0</font> | |
− | <FONT Color=#B22222>.dest_client = | ||
− | <FONT Color=#B22222>.dest_port = | ||
.channel = 0 | .channel = 0 | ||
End With | End With | ||
− | program_change( | + | program_change(sndseq, evento, 48) |
For b = 0 To note.Max | For b = 0 To note.Max | ||
− | Note_On( | + | Note_On(sndseq, evento, note[b]) |
+ | InviaEvento(sndseq) | ||
Sleep 1 | Sleep 1 | ||
− | Note_Off( | + | Note_Off(sndseq, evento, note[b]) |
+ | InviaEvento(sndseq) | ||
Next | Next | ||
Riga 259: | Riga 249: | ||
− | '''Private''' Function Connessione() As | + | '''Private''' Function Connessione() As Pointer |
+ | Dim snd As Pointer | ||
Dim rit, porta As Integer | Dim rit, porta As Integer | ||
− | rit = snd_seq_open(VarPtr( | + | rit = snd_seq_open(VarPtr(snd), "default", SND_SEQ_OPEN_OUTPUT, 0) |
If rit < 0 Then Error.Raise("Impossibile aprire il subsistema 'seq' di ALSA: " & String@(snd_strerror(rit))) | If rit < 0 Then Error.Raise("Impossibile aprire il subsistema 'seq' di ALSA: " & String@(snd_strerror(rit))) | ||
− | + | ||
− | + | Return snd | |
− | |||
− | |||
− | Return | ||
'''End''' | '''End''' | ||
− | '''Private''' Procedure program_change(ev_prch As Snd_seq_event_t, strum As Integer) | + | '''Private''' Procedure program_change(pc_seq As Pointer, ev_prch As Snd_seq_event_t, strum As Integer) |
With ev_prch | With ev_prch | ||
Riga 280: | Riga 268: | ||
.value = strum | .value = strum | ||
End With | End With | ||
− | + | ||
− | + | <FONT Color=gray>' ''Inserisce l'evento "Program_Change" nel buffer:''</font> | |
+ | snd_seq_event_output(pc_seq, ev_prch) | ||
'''End''' | '''End''' | ||
− | '''Private''' Procedure Note_On(ev_nton As Snd_seq_event_t, nota As Byte) | + | '''Private''' Procedure Note_On(nto As Pointer, ev_nton As Snd_seq_event_t, nota As Byte) |
With ev_nton | With ev_nton | ||
Riga 294: | Riga 283: | ||
End With | End With | ||
− | + | <FONT Color=gray>' ''Inserisce l'evento "Note_On" nel buffer:''</font> | |
+ | snd_seq_event_output(nto, ev_nton) | ||
'''End''' | '''End''' | ||
− | '''Private''' Procedure Note_Off(ev_ntoff As Snd_seq_event_t, nota As Byte) | + | '''Private''' Procedure Note_Off(ntf As Pointer, ev_ntoff As Snd_seq_event_t, nota As Byte) |
With ev_ntoff | With ev_ntoff | ||
Riga 307: | Riga 297: | ||
End With | End With | ||
− | + | <FONT Color=gray>' ''Inserisce l'evento "Note_Off" nel buffer:''</font> | |
+ | snd_seq_event_output(ntf, ev_ntoff) | ||
'''End''' | '''End''' | ||
− | '''Private''' Procedure InviaEvento( | + | '''Private''' Procedure InviaEvento(seqP As Pointer) |
− | + | ||
− | + | <FONT Color=gray>' ''Invia l'intero contenuto del buffer ad Alsa:''</font> | |
− | + | snd_seq_drain_output(seqP) | |
− | snd_seq_drain_output( | ||
'''End''' | '''End''' |
Versione delle 20:20, 27 feb 2016
Per inviare utilmente dati Midi ad altro Client di ALSA, non è necessario connettere i due Client (l'applicativo Gambas ed il Softsynth) mediante la funzione snd_seq_connect_to(), purché si presti attenzione ad alcuni elementi che integrano due casi.
1° caso
Nel primo caso il codice dovrà prevedere:
- la presenza della funzione di ALSA snd_seq_alloc_queue();
- il membro .queue della Struttura relativa agli eventi Midi dovrà essere posto a zero;
- al membro .dest_id e a quello .dest_port della Struttura relativa agli eventi Midi dovranno essere rispettivamente assegnati i valori dell'Id e della porta del Client (Softsynth), al quale l'applicativo Gambas dovrà inviare i dati Midi.
Mostriamo un esempio pratico:
Public Struct snd_seq_event_t type As Byte flags As Byte tag As Byte queue As Byte tick_time As Integer real_time As Integer source_client As Byte source_port As Byte dest_client As Byte dest_port As Byte channel As Byte note As Byte velocity As Byte off_velocity As Byte duration As Integer value As Integer End Struct Private sndseq As Pointer Private Const cl_dest As Byte = 128 Private Const po_dest As Byte = 0 Library "libasound:2" Private SND_SEQ_OPEN_OUTPUT As Integer = 1 Private SND_SEQ_PORT_CAP_READ As Integer = 1 Private SND_SEQ_PORT_TYPE_MIDI_GENERIC As Integer = 2 Private SND_SEQ_PORT_TYPE_APPLICATION As Integer = 1 * CInt(2 ^ 20) Private Enum SND_SEQ_EVENT_NOTEON = 6, SND_SEQ_EVENT_NOTEOFF, SND_SEQ_EVENT_KEYPRESS, SND_SEQ_EVENT_CONTROLLER = 10, SND_SEQ_EVENT_PGMCHANGE ' int snd_seq_open (snd_seq_t **handle, const char * name, int streams, int mode) ' Open the ALSA sequencer. Private Extern snd_seq_open(handle As Pointer, name As String, streams As Integer, mode As Integer) As Integer ' const char * snd_strerror (int errnum) ' Returns the message for an error code. Private Extern snd_strerror(err As Integer) As Pointer ' int snd_seq_create_simple_port (snd_seq_t *seq, const char *name, unsigned int caps, unsigned int type) ' Create a port - simple version. Private Extern snd_seq_create_simple_port(seq As Pointer, name As String, caps As Integer, type As Integer) As Integer ' int snd_seq_alloc_queue (snd_seq_t *handle) ' Allocate a queue. Private Extern snd_seq_alloc_queue(handle As Pointer) As Integer ' int snd_seq_event_output (snd_seq_t *handle, snd_seq_event_t *ev) ' Output an event. Private Extern snd_seq_event_output(handle As Pointer, ev As Snd_seq_event_t) ' int snd_seq_drain_output (snd_seq_t * seq) ' Drain output buffer to sequencer. Private Extern snd_seq_drain_output(seq As Pointer) As Integer ' int snd_seq_close (snd_seq_t *handle) ' Close the sequencer. Private Extern snd_seq_close(handle As Pointer) As Integer Public Sub Main() Dim note As Byte[] = [60, 62, 64, 65, 67, 69, 71, 72] Dim porta_source, b As Byte Dim ev As New Snd_seq_event_t porta_source = Connessione() With ev .queue = 0 .source_client = 0 .source_port = porta_source .dest_client = cl_dest .dest_port = po_dest .channel = 0 End With program_change(ev, 48) For b = 0 To note.Max Note_On(ev, note[b]) Sleep 1 Note_Off(ev, note[b]) Next snd_seq_close(sndseq) End Private Function Connessione() As Byte Dim rit, porta As Integer rit = snd_seq_open(VarPtr(sndseq), "default", SND_SEQ_OPEN_OUTPUT, 0) If rit < 0 Then Error.Raise("Impossibile aprire il subsistema 'seq' di ALSA: " & String@(snd_strerror(rit))) porta = snd_seq_create_simple_port(sndseq, "porta_", SND_SEQ_PORT_CAP_READ, SND_SEQ_PORT_TYPE_MIDI_GENERIC Or SND_SEQ_PORT_TYPE_APPLICATION) If porta < 0 Then Error.Raise("Impossibile creare la porta di uscita dati ALSA !") snd_seq_alloc_queue(sndseq) Return porta End Private Procedure program_change(ev_prch As Snd_seq_event_t, strum As Integer) With ev_prch .type = SND_SEQ_EVENT_PGMCHANGE .value = strum End With InviaEvento(ev_prch) End Private Procedure Note_On(ev_nton As Snd_seq_event_t, nota As Byte) With ev_nton .type = SND_SEQ_EVENT_NOTEON .note = nota .velocity = 64 End With InviaEvento(ev_nton) End Private Procedure Note_Off(ev_ntoff As Snd_seq_event_t, nota As Byte) With ev_ntoff .type = SND_SEQ_EVENT_NOTEOFF .note = nota .velocity = 0 End With InviaEvento(ev_ntoff) End Private Procedure InviaEvento(evento As Snd_seq_event_t) snd_seq_event_output(sndseq, evento) snd_seq_drain_output(sndseq) End
2° caso
Nel secondo caso si dovrà tenere conto di quanto segue:
- il membro .queue della Struttura relativa agli eventi Midi dovrà essere posto a zero;
- al membro .dest_id e a quello .dest_port della Struttura relativa agli eventi Midi dovranno essere rispettivamente assegnati i valori dell'Id e della porta del Client (Softsynth), al quale l'applicativo Gambas dovrà inviare i dati Midi.
Mostriamo un esempio pratico:
Public Struct snd_seq_event_t type As Byte flags As Byte tag As Byte queue As Byte tick_time As Integer real_time As Integer source_client As Byte source_port As Byte dest_client As Byte dest_port As Byte channel As Byte note As Byte velocity As Byte off_velocity As Byte duration As Integer value As Integer End Struct Library "libasound:2" Private SND_SEQ_OPEN_OUTPUT As Integer = 1 Private SND_SEQ_QUEUE_DIRECT As Byte = 253 Private Enum SND_SEQ_EVENT_NOTEON = 6, SND_SEQ_EVENT_NOTEOFF, SND_SEQ_EVENT_KEYPRESS, SND_SEQ_EVENT_CONTROLLER = 10, SND_SEQ_EVENT_PGMCHANGE ' int snd_seq_open (snd_seq_t **handle, const char * name, int streams, int mode) ' Open the ALSA sequencer. Private Extern snd_seq_open(handle As Pointer, name As String, streams As Integer, mode As Integer) As Integer ' const char * snd_strerror (int errnum) ' Returns the message for an error code. Private Extern snd_strerror(err As Integer) As Pointer ' int snd_seq_event_output (snd_seq_t *handle, snd_seq_event_t *ev) ' Output an event. Private Extern snd_seq_event_output(handle As Pointer, ev As Snd_seq_event_t) ' int snd_seq_drain_output (snd_seq_t * seq) ' Drain output buffer to sequencer. Private Extern snd_seq_drain_output(seq As Pointer) As Integer ' int snd_seq_close (snd_seq_t *handle) ' Close the sequencer. Private Extern snd_seq_close(handle As Pointer) As Integer Public Sub Main() Dim sndseq As Pointer Dim note As Byte[] = [60, 62, 64, 65, 67, 69, 71, 72] Dim b As Byte Dim evento As New Snd_seq_event_t sndseq = Connessione() With evento .queue = SND_SEQ_QUEUE_DIRECT .dest_client = 128 .dest_port = 0 .channel = 0 End With program_change(sndseq, evento, 48) For b = 0 To note.Max Note_On(sndseq, evento, note[b]) InviaEvento(sndseq) Sleep 1 Note_Off(sndseq, evento, note[b]) InviaEvento(sndseq) Next snd_seq_close(sndseq) End Private Function Connessione() As Pointer Dim snd As Pointer Dim rit, porta As Integer rit = snd_seq_open(VarPtr(snd), "default", SND_SEQ_OPEN_OUTPUT, 0) If rit < 0 Then Error.Raise("Impossibile aprire il subsistema 'seq' di ALSA: " & String@(snd_strerror(rit))) Return snd End Private Procedure program_change(pc_seq As Pointer, ev_prch As Snd_seq_event_t, strum As Integer) With ev_prch .type = SND_SEQ_EVENT_PGMCHANGE .value = strum End With ' Inserisce l'evento "Program_Change" nel buffer: snd_seq_event_output(pc_seq, ev_prch) End Private Procedure Note_On(nto As Pointer, ev_nton As Snd_seq_event_t, nota As Byte) With ev_nton .type = SND_SEQ_EVENT_NOTEON .note = nota .velocity = 64 End With ' Inserisce l'evento "Note_On" nel buffer: snd_seq_event_output(nto, ev_nton) End Private Procedure Note_Off(ntf As Pointer, ev_ntoff As Snd_seq_event_t, nota As Byte) With ev_ntoff .type = SND_SEQ_EVENT_NOTEOFF .note = nota .velocity = 0 End With ' Inserisce l'evento "Note_Off" nel buffer: snd_seq_event_output(ntf, ev_ntoff) End Private Procedure InviaEvento(seqP As Pointer) ' Invia l'intero contenuto del buffer ad Alsa: snd_seq_drain_output(seqP) End
Esempio più essenziale per invio dati Midi
Mostriamo ora la modalità più breve ed essenziale per inviare ad altro Client di Alsa alcuni eventi Midi, e nella quale non è prevista la creazione di porte del nostro Client applicativo:
Public Struct snd_seq_event_t type As Byte flags As Byte tag As Byte queue As Byte tick_time As Integer real_time As Integer source_client As Byte source_port As Byte dest_client As Byte dest_port As Byte channel As Byte note As Byte velocity As Byte off_velocity As Byte duration As Integer value As Integer End Struct Library "libasound:2" Private SND_SEQ_OPEN_OUTPUT As Integer = 1 Private Enum SND_SEQ_EVENT_NOTEON = 6, SND_SEQ_EVENT_NOTEOFF Private SND_SEQ_QUEUE_DIRECT As Byte = 253 ' int snd_seq_open (snd_seq_t **handle, const char * name, int streams, int mode) ' Open the ALSA sequencer. Private Extern snd_seq_open(handle As Pointer, name As String, streams As Integer, mode As Integer) As Integer ' const char * snd_strerror (int errnum) ' Returns the message for an error code. Private Extern snd_strerror(err As Integer) As Pointer ' int snd_seq_event_output_direct (snd_seq_t *handle, snd_seq_event_t *ev) ' Output an event directly to the sequencer NOT through output buffer. Private Extern snd_seq_event_output_direct(handle As Pointer, ev As Snd_seq_event_t) As Integer ' int snd_seq_close (snd_seq_t *handle) ' Close the sequencer. Private Extern snd_seq_close(handle As Pointer) As Integer Public Sub Main() Dim seq As Pointer Dim evento As New Snd_seq_event_t Dim rit As Integer snd_seq_open(VarPtr(seq), "default", SND_SEQ_OPEN_OUTPUT, 0) If rit < 0 Then Error.Raise("Impossibile aprire il subsistema 'seq' di ALSA: " & String@(snd_strerror(rit))) With evento .type = SND_SEQ_EVENT_NOTEON .queue = SND_SEQ_QUEUE_DIRECT .dest_client = 128 .dest_port = 0 .channel = 0 .note = 64 .velocity = 100 End With snd_seq_event_output_direct(seq, evento) Sleep 1 evento.type = SND_SEQ_EVENT_NOTEOFF snd_seq_event_output_direct(seq, evento) snd_seq_close(seq) End