aboutsummaryrefslogtreecommitdiffstats
path: root/plugins/alsa/alsa-core-ctl.c
blob: 0ef11e18a19896b21a519d640d72a097201d1ff8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
/*
 * Copyright(C) 2018 "IoT.bzh"
 * Author Fulup Ar Foll <fulup@iot.bzh>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http : //www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License

for the specific language governing permissions and
 * limitations under the License.
 *
 * reference :
 * https://github.com/zonque/simple-alsa-loop/blob/master/loop.c
 * https://www.alsa-project.org/alsa-doc/alsa-lib/_2test_2pcm_8c-example.html#a31
 *
 */

#define _GNU_SOURCE  // needed for vasprintf

#include "alsa-softmixer.h"
#include <pthread.h>
#include <sys/syscall.h>

typedef struct {
    SoftMixerT *mixer;
    sd_event_source* evtsrc;
    const char* uid;
    AlsaSndCtlT *sndcard;
    sd_event *sdLoop;
} SubscribeHandleT;

PUBLIC snd_ctl_elem_id_t *AlsaCtlGetNumidElemId(SoftMixerT *mixer, AlsaSndCtlT *sndcard, int numid) {
    char string[32];
    int error;
    int index;
    snd_ctl_elem_list_t *ctlList = NULL;
    snd_ctl_elem_id_t *elemId;

    snd_ctl_elem_list_alloca(&ctlList);

    if ((error = snd_ctl_elem_list(sndcard->ctl, ctlList)) < 0) {
        AFB_ApiError(mixer->api, "AlsaCtlGetNumidElemId [%s] fail retrieve controls", ALSA_CTL_UID(sndcard->ctl, string));
        goto OnErrorExit;
    }

    if ((error = snd_ctl_elem_list_alloc_space(ctlList, snd_ctl_elem_list_get_count(ctlList))) < 0) {
        AFB_ApiError(mixer->api, "AlsaCtlGetNumidElemId [%s] fail retrieve count", ALSA_CTL_UID(sndcard->ctl, string));
        goto OnErrorExit;
    }

    // Fulup: do not understand why snd_ctl_elem_list should be call twice to get a valid ctlCount
    if ((error = snd_ctl_elem_list(sndcard->ctl, ctlList)) < 0) {
        AFB_ApiError(mixer->api, "AlsaCtlGetNumidElemId [%s] fail retrieve controls", ALSA_CTL_UID(sndcard->ctl, string));
        goto OnErrorExit;
    }

    // loop on control to find the right one
    int ctlCount = snd_ctl_elem_list_get_used(ctlList);
    for (index = 0; index < ctlCount; index++) {

        if (numid == snd_ctl_elem_list_get_numid(ctlList, index)) {
            snd_ctl_elem_id_malloc(&elemId);
            snd_ctl_elem_list_get_id(ctlList, index, elemId);
            break;
        }
    }

    if (index == ctlCount) {
        AFB_ApiNotice(mixer->api, "AlsaCtlGetNumidElemId [%s] fail get numid=%i count", ALSA_CTL_UID(sndcard->ctl, string), numid);
        goto OnErrorExit;
    }

    // clear ctl list and return elemid
    snd_ctl_elem_list_clear(ctlList);
    return elemId;

OnErrorExit:
    if (ctlList) snd_ctl_elem_list_clear(ctlList);
    return NULL;
}

PUBLIC snd_ctl_elem_id_t *AlsaCtlGetNameElemId(SoftMixerT *mixer, AlsaSndCtlT *sndcard, const char *ctlName) {
    int error;
    int index;
    snd_ctl_elem_list_t *ctlList = NULL;
    snd_ctl_elem_id_t *elemId;

    snd_ctl_elem_list_alloca(&ctlList);

    if ((error = snd_ctl_elem_list(sndcard->ctl, ctlList)) < 0) {
        AFB_ApiError(mixer->api, "AlsaCtlGetNameElemId cardid='%s' cardname='%s' fail retrieve controls", sndcard->cid.cardid, sndcard->cid.name);
        goto OnErrorExit;
    }

    if ((error = snd_ctl_elem_list_alloc_space(ctlList, snd_ctl_elem_list_get_count(ctlList))) < 0) {
        AFB_ApiError(mixer->api, "AlsaCtlGetNameElemId cardid='%s' cardname='%s' fail retrieve count", sndcard->cid.cardid, sndcard->cid.name);
        goto OnErrorExit;
    }

    // Fulup: do not understand why snd_ctl_elem_list should be call twice to get a valid ctlCount
    if ((error = snd_ctl_elem_list(sndcard->ctl, ctlList)) < 0) {
        AFB_ApiError(mixer->api, "AlsaCtlGetNameElemId cardid='%s' cardname='%s' fail retrieve controls", sndcard->cid.cardid, sndcard->cid.name);
        goto OnErrorExit;
    }

    // loop on control to find the right one
    int ctlCount = snd_ctl_elem_list_get_used(ctlList);
    for (index = 0; index < ctlCount; index++) {

        if (strcasestr(snd_ctl_elem_list_get_name(ctlList, index), ctlName)) {
            snd_ctl_elem_id_malloc(&elemId);
            snd_ctl_elem_list_get_id(ctlList, index, elemId);
            break;
        }
    }

    if (index == ctlCount) {
        AFB_ApiNotice(mixer->api, "AlsaCtlGetNameElemId cardid='%s' cardname='%s' ctl not found name=%s", sndcard->cid.cardid, sndcard->cid.name, ctlName);
        goto OnErrorExit;
    }

    // clear ctl list and return elemid
    snd_ctl_elem_list_clear(ctlList);
    return elemId;

OnErrorExit:
    if (ctlList) snd_ctl_elem_list_clear(ctlList);
    return NULL;
}

PUBLIC snd_ctl_t *AlsaCtlOpenCtl(SoftMixerT *mixer, const char *cardid) {
    int error;
    snd_ctl_t *ctl;

    if (!cardid) goto OnErrorExit;

    if ((error = snd_ctl_open(&ctl, cardid, SND_CTL_READONLY)) < 0) {
        cardid = "Not Defined";
        goto OnErrorExit;
    }

    return ctl;

OnErrorExit:
    AFB_ApiError(mixer->api, "AlsaCtlOpenCtl: fail to find sndcard by id= %s", cardid);
    return NULL;
}


STATIC void CtlElemIdDisplay(SoftMixerT *mixer, snd_ctl_elem_info_t *elemInfo, snd_ctl_elem_value_t *elemData) {

    int numid = snd_ctl_elem_info_get_numid(elemInfo);
    int count = snd_ctl_elem_info_get_count(elemInfo);
    const char* name = snd_ctl_elem_info_get_name(elemInfo);
    snd_ctl_elem_type_t elemType = snd_ctl_elem_info_get_type(elemInfo);


    if (!elemData) {
        AFB_ApiWarning(mixer->api, "CtlElemIdDisplay: numid=%d name=%s value=unreadable", numid, name);
    } else
        for (int idx = 0; idx < count; idx++) {
            long valueL;

            switch (elemType) {
                case SND_CTL_ELEM_TYPE_BOOLEAN:
                    valueL = snd_ctl_elem_value_get_boolean(elemData, idx);
                    AFB_ApiWarning(mixer->api, "CtlElemIdDisplay: numid=%d name=%s value=%ld", numid, name, valueL);
                    break;
                case SND_CTL_ELEM_TYPE_INTEGER:
                    valueL = snd_ctl_elem_value_get_integer(elemData, idx);
                    AFB_ApiWarning(mixer->api, "CtlElemIdDisplay: numid=%d name=%s value=%ld", numid, name, valueL);
                    break;
                case SND_CTL_ELEM_TYPE_INTEGER64:
                    valueL = snd_ctl_elem_value_get_integer64(elemData, idx);
                    AFB_ApiWarning(mixer->api, "CtlElemIdDisplay: numid=%d name=%s value=%ld", numid, name, valueL);
                    break;
                case SND_CTL_ELEM_TYPE_ENUMERATED:
                    valueL = snd_ctl_elem_value_get_enumerated(elemData, idx);
                    AFB_ApiWarning(mixer->api, "CtlElemIdDisplay: numid=%d name=%s value=%ld", numid, name, valueL);
                    break;
                case SND_CTL_ELEM_TYPE_BYTES:
                    valueL = snd_ctl_elem_value_get_byte(elemData, idx);
                    AFB_ApiWarning(mixer->api, "CtlElemIdDisplay: numid=%d name=%s value=%ld", numid, name, valueL);
                    break;
                case SND_CTL_ELEM_TYPE_IEC958:
                default:
                    AFB_ApiWarning(mixer->api, "CtlElemIdDisplay: numid=%d name=%s Unsupported type=%d", numid, name, elemType);
                    break;
            }
        }
}

PUBLIC int CtlElemIdGetLong(SoftMixerT *mixer, AlsaSndCtlT *sndcard, snd_ctl_elem_id_t *elemId, long *value) {
    int error;
    snd_ctl_elem_value_t *elemData;
    snd_ctl_elem_info_t *elemInfo;

    snd_ctl_elem_info_alloca(&elemInfo);
    snd_ctl_elem_info_set_id(elemInfo, elemId);
    if (snd_ctl_elem_info(sndcard->ctl, elemInfo) < 0) goto OnErrorExit;
    if (!snd_ctl_elem_info_is_readable(elemInfo)) goto OnErrorExit;

    // as we have static rate/channel we should have only one boolean as value

    snd_ctl_elem_value_alloca(&elemData);
    snd_ctl_elem_value_set_id(elemData, elemId);
    error = snd_ctl_elem_read(sndcard->ctl, elemData);
    if (error) {
        elemData = NULL;
        goto OnErrorExit;
    }

    // value=1 when active and 0 when not active
    *value = (int) snd_ctl_elem_value_get_integer(elemData, 0);

    return 0;

OnErrorExit:
    CtlElemIdDisplay(mixer, elemInfo, elemData);
    return -1;
}

PUBLIC int CtlElemIdSetLong(SoftMixerT *mixer, AlsaSndCtlT *sndcard, snd_ctl_elem_id_t *elemId, long value) {
    snd_ctl_elem_value_t *elemData;
    snd_ctl_elem_info_t *elemInfo;
    const char* name;
    int error, numid;

    snd_ctl_elem_info_alloca(&elemInfo);
    snd_ctl_elem_info_set_id(elemInfo, elemId);
    if (snd_ctl_elem_info(sndcard->ctl, elemInfo) < 0) goto OnErrorExit;

    if (!snd_ctl_elem_info_is_writable(elemInfo)) goto OnErrorExit;

    int count = snd_ctl_elem_info_get_count(elemInfo);
    if (count == 0) goto OnErrorExit;

    snd_ctl_elem_value_alloca(&elemData);
    snd_ctl_elem_value_set_id(elemData, elemId);
    error = snd_ctl_elem_read(sndcard->ctl, elemData);
    if (error) goto OnErrorExit;

    for (int index = 0; index < count; index++) {
        snd_ctl_elem_value_set_integer(elemData, index, value);
    }

    error = snd_ctl_elem_write(sndcard->ctl, elemData);
    if (error) goto OnErrorExit;

    return 0;

OnErrorExit:
    numid = snd_ctl_elem_info_get_numid(elemInfo);
    name = snd_ctl_elem_info_get_name(elemInfo);
    AFB_ApiError(mixer->api, "CtlElemIdSetInt: numid=%d name=%s not writable", numid, name);
    return -1;
}

// Clone of AlsaLib snd_card_load2 static function

PUBLIC snd_ctl_card_info_t *AlsaCtlGetInfo(SoftMixerT *mixer, const char *cardid) {
    int error;
    snd_ctl_t *ctl;

    if ((error = snd_ctl_open(&ctl, cardid, SND_CTL_READONLY)) < 0) {
        cardid = "Not Defined";
        goto OnErrorExit;
    }

    snd_ctl_card_info_t *cardInfo = malloc(snd_ctl_card_info_sizeof());
    if ((error = snd_ctl_card_info(ctl, cardInfo)) < 0) {
        goto OnErrorExit;
    }
    return cardInfo;

OnErrorExit:
    AFB_ApiError(mixer->api, "AlsaCtlGetInfo: fail to find sndcard by id= %s", cardid);
    return NULL;
}

PUBLIC int AlsaCtlNumidSetLong(SoftMixerT *mixer, AlsaSndCtlT *sndcard, int numid, long value) {

    snd_ctl_elem_id_t *elemId = AlsaCtlGetNumidElemId(mixer, sndcard, numid);
    if (!elemId) {
        AFB_ApiError(mixer->api, "AlsaCtlNumidSetLong cardid=%s cardname=%s fail to find numid=%d", sndcard->cid.cardid, sndcard->cid.longname, numid);
        goto OnErrorExit;
    }

    int error = CtlElemIdSetLong(mixer, sndcard, elemId, value);
    if (error) {
        AFB_ApiError(mixer->api, "AlsaCtlNumidSetLong cardid=%s cardname=%s fail to set numid=%d value=%ld", sndcard->cid.cardid, sndcard->cid.longname, numid, value);
        goto OnErrorExit;
    }

    return 0;
OnErrorExit:
    return -1;
}

PUBLIC int AlsaCtlNumidGetLong(SoftMixerT *mixer, AlsaSndCtlT *sndcard, int numid, long* value) {

    snd_ctl_elem_id_t *elemId = AlsaCtlGetNumidElemId(mixer, sndcard, numid);
    if (!elemId) {
        AFB_ApiError(mixer->api, "AlsaCtlNumidGetLong cardid=%s cardname=%s fail to find numid=%d", sndcard->cid.cardid, sndcard->cid.longname, numid);
        goto OnErrorExit;
    }

    int error = CtlElemIdGetLong(mixer, sndcard, elemId, value);
    if (error) {
        AFB_ApiError(mixer->api, "AlsaCtlNumidGetLong cardid=%s cardname=%s fail to get numid=%d value", sndcard->cid.cardid, sndcard->cid.longname, numid);
        goto OnErrorExit;
    }

    return 0;
OnErrorExit:
    return -1;
}

PUBLIC int AlsaCtlNameSetLong(SoftMixerT *mixer, AlsaSndCtlT *sndcard, const char *ctlName, long value) {

    snd_ctl_elem_id_t *elemId = AlsaCtlGetNameElemId(mixer, sndcard, ctlName);
    if (!elemId) {
        AFB_ApiError(mixer->api, "AlsaCtlNameSetLong cardid=%s cardname=%s fail to find crlName=%s", sndcard->cid.cardid, sndcard->cid.longname, ctlName);
        goto OnErrorExit;
    }

    int error = CtlElemIdSetLong(mixer, sndcard, elemId, value);
    if (error) {
        AFB_ApiError(mixer->api, "AlsaCtlNameSetLong cardid=%s cardname=%s fail to set crlName=%s value=%ld", sndcard->cid.cardid, sndcard->cid.longname, ctlName, value);
        goto OnErrorExit;
    }

    return 0;
OnErrorExit:
    return -1;
}

PUBLIC int AlsaCtlNameGetLong(SoftMixerT *mixer, AlsaSndCtlT *sndcard, const char *ctlName, long* value) {

    snd_ctl_elem_id_t *elemId = AlsaCtlGetNameElemId(mixer, sndcard, ctlName);
    if (!elemId) {
        AFB_ApiError(mixer->api, "AlsaCtlNameGetLong cardid=%s cardname=%s fail to find crlName=%s", sndcard->cid.cardid, sndcard->cid.longname, ctlName);
        goto OnErrorExit;
    }

    int error = CtlElemIdGetLong(mixer, sndcard, elemId, value);
    if (error) {
        AFB_ApiError(mixer->api, "AlsaCtlNameGetLong cardid=%s cardname=%s fail to get crlName=%s value", sndcard->cid.cardid, sndcard->cid.longname, ctlName);
        goto OnErrorExit;
    }

    return 0;
OnErrorExit:
    return -1;
}

STATIC int AlsaCtlMakeControl(SoftMixerT *mixer, AlsaSndCtlT *sndcard, const char *ctlName, int ctlCount, int ctlMin, int ctlMax, int ctlStep) {
    snd_ctl_elem_type_t ctlType;
    snd_ctl_elem_info_t *elemInfo;
    int error;

    snd_ctl_elem_info_alloca(&elemInfo);
    if (ctlName) snd_ctl_elem_info_set_name(elemInfo, ctlName);
    snd_ctl_elem_info_set_interface(elemInfo, SND_CTL_ELEM_IFACE_MIXER);
    snd_ctl_elem_info(sndcard->ctl, elemInfo);

    // map volume to sndcard device+subdev=0
    snd_ctl_elem_info_set_device(elemInfo, sndcard->cid.device);
    snd_ctl_elem_info_set_subdevice(elemInfo, sndcard->cid.subdev);
    snd_ctl_elem_info_set_device(elemInfo, 0);
    snd_ctl_elem_info_set_subdevice(elemInfo, 0);

    // only two types implemented
    if (ctlMin == 0 && ctlMax == 1) ctlType = SND_CTL_ELEM_TYPE_BOOLEAN;
    else ctlType = SND_CTL_ELEM_TYPE_INTEGER;

    switch (ctlType) {
        case SND_CTL_ELEM_TYPE_BOOLEAN:
            error = snd_ctl_add_boolean_elem_set(sndcard->ctl, elemInfo, 1, ctlCount);
            if (error) goto OnErrorExit;
            break;

        case SND_CTL_ELEM_TYPE_INTEGER:
            error = snd_ctl_add_integer_elem_set(sndcard->ctl, elemInfo, 1, ctlCount, ctlMin, ctlMax, ctlStep);
            if (error) goto OnErrorExit;
            break;

        default:
            AFB_ApiError(mixer->api, "AlsaCtlMakeControl: mixer=%s cardid=%s cardname=%s fail to create %s(control)", mixer->uid, sndcard->cid.cardid, sndcard->cid.longname, ctlName);
            goto OnErrorExit;
    }

    // retrieve newly created control numid
    int numid = snd_ctl_elem_info_get_numid(elemInfo);
    return numid;

OnErrorExit:
    return -1;
}

PUBLIC int AlsaCtlCreateControl(SoftMixerT *mixer, AlsaSndCtlT *sndcard, char* ctlName, int ctlCount, int ctlMin, int ctlMax, int ctlStep, long value) {
    int numid = -1;

    // if control does not exist then create
    snd_ctl_elem_id_t *elemId = AlsaCtlGetNameElemId(mixer, sndcard, ctlName);
    if (elemId) {
        numid = snd_ctl_elem_id_get_numid(elemId);
    } else {
        // create or get numid control when already exist
        numid = AlsaCtlMakeControl(mixer, sndcard, ctlName, ctlCount, ctlMin, ctlMax, ctlStep);
        if (numid <= 0) {
            AFB_ApiError(mixer->api, "AlsaCtlCreateControl cardid=%s cardname=%s fail to create ctlName=%s", sndcard->cid.cardid, sndcard->cid.longname, ctlName);
            goto OnErrorExit;
        }

        elemId = AlsaCtlGetNumidElemId(mixer, sndcard, numid);
    }

    int error = CtlElemIdSetLong(mixer, sndcard, elemId, value);
    if (error) {
        AFB_ApiError(mixer->api, "AlsaCtlCreateControl cardid=%s cardname=%s fail to set ctlName=%s Numid=%d", sndcard->cid.cardid, sndcard->cid.longname, ctlName, numid);
        goto OnErrorExit;
    }

    AFB_ApiNotice(mixer->api, "AlsaCtlCreateControl cardid=%s cardname=%s ctl create name=%s numid=%d value=%ld", sndcard->cid.cardid, sndcard->cid.longname, ctlName, numid, value);
    return numid;
OnErrorExit:
    return -1;
}

STATIC int CtlSubscribeEventCB(sd_event_source* src, int fd, uint32_t revents, void* userData) {
    int error;
    SubscribeHandleT *sHandle = (SubscribeHandleT*) userData;
    AlsaSndCtlT *sndcard = sHandle->sndcard;
    SoftMixerT *mixer = sHandle->mixer;
    snd_ctl_event_t *eventId;
    snd_ctl_elem_id_t *elemId;
    long value;
    int index;

    if ((revents & EPOLLHUP) != 0) {
        AFB_ApiNotice(mixer->api, "CtlSubscribeEventCB hanghup [card:%s disconnected]", sHandle->uid);
        goto OnSuccessExit;
    }

    if ((revents & EPOLLIN) == 0) goto OnSuccessExit;

    // initialise event structure on stack
    snd_ctl_event_alloca(&eventId);
    snd_ctl_elem_id_alloca(&elemId);

    error = snd_ctl_read(sndcard->ctl, eventId);
    if (error < 0) goto OnErrorExit;

    // we only process sndctrl element
    if (snd_ctl_event_get_type(eventId) != SND_CTL_EVENT_ELEM) goto OnSuccessExit;

    // we only process value changed events
    unsigned int eventMask = snd_ctl_event_elem_get_mask(eventId);
    if (!(eventMask & SND_CTL_EVENT_MASK_VALUE)) goto OnSuccessExit;

    // extract element from event and get value    
    snd_ctl_event_elem_get_id(eventId, elemId);
    error = CtlElemIdGetLong(mixer, sHandle->sndcard, elemId, &value);
    if (error) goto OnErrorExit;
    
    // get numdid and name from elemId
    snd_ctl_elem_info_t *elemInfo;
    snd_ctl_elem_info_alloca(&elemInfo);
    snd_ctl_elem_info_set_id(elemInfo, elemId);
    if (snd_ctl_elem_info(sndcard->ctl, elemInfo) < 0) goto OnErrorExit;
    int numid = snd_ctl_elem_info_get_numid(elemInfo);
    const char *name= snd_ctl_elem_info_get_name(elemInfo);

    for (index = 0; sndcard->registry[index]; index++) {
        if (sndcard->registry[index]->numid == numid) {

            switch (sndcard->registry[index]->type) {
                case FONTEND_NUMID_RUN:
                    (void) snd_pcm_pause(sndcard->registry[index]->pcm->handle, (int) (!value));
                    AFB_ApiNotice(mixer->api, "CtlSubscribeEventCB:%s numid=%d name=%s active=%ld", sHandle->uid, numid, name, value);
                    break;
                case FONTEND_NUMID_PAUSE:
                    AFB_ApiNotice(mixer->api, "CtlSubscribeEventCB:%s numid=%d name=%s pause=%ld", sHandle->uid, numid, name, value);
                    (void) snd_pcm_pause(sndcard->registry[index]->pcm->handle, (int) value);
                    break;
                case FONTEND_NUMID_IGNORE:
                default:
                    AFB_ApiInfo(mixer->api, "CtlSubscribeEventCB:%s numid=%d name=%s ignored=%ld", sHandle->uid, numid, name, value);
            }
            break;
        }
    }
    if (index == sndcard->rcount) {
        AFB_ApiNotice(mixer->api, "CtlSubscribeEventCB:%s numid=%d (unknown)", sHandle->uid, numid);
    }

OnSuccessExit:
    return 0;

OnErrorExit:
    AFB_ApiInfo(mixer->api, "CtlSubscribeEventCB: ignored unsupported event");
    return 0;
}

PUBLIC snd_ctl_t* AlsaCrlFromPcm(SoftMixerT *mixer, snd_pcm_t *pcm) {
    char buffer[32];
    int error;
    snd_ctl_t *ctl;
    snd_pcm_info_t *pcmInfo;

    snd_pcm_info_alloca(&pcmInfo);
    if ((error = snd_pcm_info(pcm, pcmInfo)) < 0) goto OnErrorExit;

    int pcmCard = snd_pcm_info_get_card(pcmInfo);
    snprintf(buffer, sizeof (buffer), "hw:%i", pcmCard);
    if ((error = snd_ctl_open(&ctl, buffer, SND_CTL_READONLY)) < 0) goto OnErrorExit;

    return ctl;

OnErrorExit:
    return NULL;
}

PUBLIC int AlsaCtlSubscribe(SoftMixerT *mixer, const char *uid, AlsaSndCtlT *sndcard) {
    int error;
    char string [32];
    struct pollfd pfds;
    SubscribeHandleT *handle = malloc(sizeof (SubscribeHandleT));

    handle->mixer = mixer;
    handle->sndcard = sndcard;
    handle->uid = uid;

    // subscribe for sndctl events attached to cardid
    if ((error = snd_ctl_subscribe_events(handle->sndcard->ctl, 1)) < 0) {
        AFB_ApiError(mixer->api, "AlsaCtlSubscribe: fail sndcard=%s to subscribe events", ALSA_CTL_UID(handle->sndcard->ctl, string));
        goto OnErrorExit;
    }

    // get pollfd attach to this sound board
    int count = snd_ctl_poll_descriptors(handle->sndcard->ctl, &pfds, 1);
    if (count != 1) {
        AFB_ApiError(mixer->api, "AlsaCtlSubscribe: fail sndcard=%s get poll descriptors", ALSA_CTL_UID(handle->sndcard->ctl, string));
        goto OnErrorExit;
    }

    // Registry sound event to binder main loop
    if ((error = sd_event_add_io(mixer->sdLoop, &handle->evtsrc, pfds.fd, EPOLLIN, CtlSubscribeEventCB, handle)) < 0) {
        AFB_ApiError(mixer->api, "AlsaCtlSubscribe: Fail sndcard=%s adding mainloop", ALSA_CTL_UID(handle->sndcard->ctl, string));
        goto OnErrorExit;
    }

    return 0;

OnErrorExit:
    return -1;
}

PUBLIC int AlsaCtlRegister(SoftMixerT *mixer, AlsaSndCtlT *sndcard, AlsaPcmCtlT *pcmdev, RegistryNumidT type, int numid) {
    int index;

    for (index = 0; index < sndcard->rcount; index++) {
        if (!sndcard->registry[index]) break;
    }

    if (index == sndcard->rcount) {
        AFB_ApiError(mixer->api, "AlsaCtlRegister cardid=%s cardname=%s to many audio stream max=%ld", sndcard->cid.cardid, sndcard->cid.longname, sndcard->rcount);
        goto OnErrorExit;
    }

    // If 1st registration then register to card event
    if (index == 0) {
        AlsaCtlSubscribe(mixer, sndcard->cid.cardid, sndcard);
    }

    // store PCM in order to pause/resume depending on event
    RegistryEntryPcmT *entry = calloc(1, sizeof (RegistryEntryPcmT));
    sndcard->registry[index] = entry;
    entry->pcm = pcmdev;
    entry->numid = numid;
    entry->type = type;

    return 0;

OnErrorExit:
    return -1;
}