aboutsummaryrefslogtreecommitdiff
path: root/src/conversation/gnunet-helper-audio-record.c
blob: 82bb6d5b3add5f23898136aaee218376f04f736c (plain) (blame)
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
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
/*
     This file is part of GNUnet.
     Copyright (C) 2013 GNUnet e.V.

     GNUnet is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published
     by the Free Software Foundation; either version 3, or (at your
     option) any later version.

     GNUnet is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
*/
/**
 * @file conversation/gnunet-helper-audio-record.c
 * @brief program to record audio data from the microphone
 * @author Siomon Dieterle
 * @author Andreas Fuchs
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_protocols.h"
#include "conversation.h"
#include "gnunet_constants.h"
#include "gnunet_core_service.h"

#include <pulse/simple.h>
#include <pulse/error.h>
#include <pulse/rtclock.h>

#include <pulse/pulseaudio.h>
#include <opus/opus.h>
#include <opus/opus_types.h>
#include <ogg/ogg.h>

#define DEBUG_RECORD_PURE_OGG 1

/**
 * Sampling rate
 */
#define SAMPLING_RATE 48000

/**
 * How many ms of audio to buffer before encoding them.
 * Possible values:
 * 60, 40, 20, 10, 5, 2.5
 */
#define FRAME_SIZE_MS 40

/**
 * How many samples to buffer before encoding them.
 */
#define FRAME_SIZE (SAMPLING_RATE / 1000 * FRAME_SIZE_MS)

/**
 * Pages are commited when their size goes over this value.
 * Note that in practice we flush pages VERY often (every frame),
 * which means that pages NEVER really get to be this big.
 * With one-packet-per-page, pages are roughly 100-300 bytes each.
 *
 * This value is chosen to make MAX_PAYLOAD_BYTES=1024 fit
 * into a single page.
 */
#define PAGE_WATERLINE 800

/**
 * Maximum length of opus payload
 */
#define MAX_PAYLOAD_BYTES 1024

/**
 * Number of channels
 */
#define CHANNELS 1

/**
 * Configures the encoder's expected packet loss percentage.
 *
 * Higher values will trigger progressively more loss resistant behavior
 * in the encoder at the expense of quality at a given bitrate
 * in the lossless case, but greater quality under loss.
 */
#define CONV_OPUS_PACKET_LOSS_PERCENTAGE 1

/**
 * Configures the encoder's computational complexity.
 *
 * The supported range is 0-10 inclusive with 10 representing
 * the highest complexity.
 */
#define CONV_OPUS_ENCODING_COMPLEXITY 10

/**
 * Configures the encoder's use of inband forward error correction (FEC).
 *
 * Note: This is only applicable to the LPC layer.
 */
#define CONV_OPUS_INBAND_FEC 1

/**
 * Configures the type of signal being encoded.
 *
 * This is a hint which helps the encoder's mode selection.
 *
 * Possible values:
 * OPUS_AUTO - (default) Encoder detects the type automatically.
 * OPUS_SIGNAL_VOICE - Bias thresholds towards choosing LPC or Hybrid modes.
 * OPUS_SIGNAL_MUSIC - Bias thresholds towards choosing MDCT modes.
 */
#define CONV_OPUS_SIGNAL OPUS_SIGNAL_VOICE

/**
 * Coding mode.
 *
 * Possible values:
 * OPUS_APPLICATION_VOIP - gives best quality at a given bitrate for voice
 * signals. It enhances the input signal by high-pass filtering and
 * emphasizing formants and harmonics. Optionally it includes in-band forward
 * error correction to protect against packet loss. Use this mode for typical
 * VoIP applications. Because of the enhancement, even at high bitrates
 * the output may sound different from the input.
 * OPUS_APPLICATION_AUDIO - gives best quality at a given bitrate for most
 * non-voice signals like music. Use this mode for music and mixed
 * (music/voice) content, broadcast, and applications requiring less than
 * 15 ms of coding delay.
 * OPUS_APPLICATION_RESTRICTED_LOWDELAY - configures low-delay mode that
 * disables the speech-optimized mode in exchange for slightly reduced delay.
 * This mode can only be set on an newly initialized or freshly reset encoder
 * because it changes the codec delay.
 */
#define CONV_OPUS_APP_TYPE OPUS_APPLICATION_VOIP

/**
 * Specification for recording. May change in the future to spec negotiation.
 */
static pa_sample_spec sample_spec = {
  .format = PA_SAMPLE_FLOAT32LE,
  .rate = SAMPLING_RATE,
  .channels = CHANNELS
};

GNUNET_NETWORK_STRUCT_BEGIN

/* OggOpus spec says the numbers must be in little-endian order */
struct OpusHeadPacket
{
  uint8_t magic[8];
  uint8_t version;
  uint8_t channels;
  uint16_t preskip GNUNET_PACKED;
  uint32_t sampling_rate GNUNET_PACKED;
  uint16_t gain GNUNET_PACKED;
  uint8_t channel_mapping;
};

struct OpusCommentsPacket
{
  uint8_t magic[8];
  uint32_t vendor_length;
  /* followed by:
     char vendor[vendor_length];
     uint32_t string_count;
     followed by @a string_count pairs of:
       uint32_t string_length;
       char string[string_length];
   */
};

GNUNET_NETWORK_STRUCT_END

/**
 * Pulseaudio mainloop api
 */
static pa_mainloop_api *mainloop_api;

/**
 * Pulseaudio mainloop
 */
static pa_mainloop *m;

/**
 * Pulseaudio context
 */
static pa_context *context;

/**
 * Pulseaudio recording stream
 */
static pa_stream *stream_in;

/**
 * Pulseaudio io events
 */
static pa_io_event *stdio_event;

/**
 * OPUS encoder
 */
static OpusEncoder *enc;

/**
 * Buffer for encoded data
 */
static unsigned char *opus_data;

/**
 * PCM data buffer for one OPUS frame
 */
static float *pcm_buffer;

/**
 * Length of the pcm data needed for one OPUS frame
 */
static int pcm_length;

/**
 * Audio buffer
 */
static char *transmit_buffer;

/**
 * Length of audio buffer
 */
static size_t transmit_buffer_length;

/**
 * Read index for transmit buffer
 */
static size_t transmit_buffer_index;

/**
 * Audio message skeleton
 */
static struct AudioMessage *audio_message;

/**
 * Ogg muxer state
 */
static ogg_stream_state os;

/**
 * Ogg packet id
 */
static int32_t packet_id;

/**
 * Ogg granule for current packet
 */
static int64_t enc_granulepos;

#ifdef DEBUG_RECORD_PURE_OGG
/**
 * 1 to not to write GNUnet message headers,
 * producing pure playable ogg output
 */
static int dump_pure_ogg;
#endif

/**
 * Pulseaudio shutdown task
 */
static void
quit (int ret)
{
  mainloop_api->quit (mainloop_api, ret);
  exit (ret);
}


static void
write_data (const char *ptr, size_t msg_size)
{
  ssize_t ret;
  size_t off;
  off = 0;
  while (off < msg_size)
  {
    ret = write (1, &ptr[off], msg_size - off);
    if (0 >= ret)
    {
      if (-1 == ret)
        GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "write");
      quit (2);
    }
    off += ret;
  }
}

static void
write_page (ogg_page *og)
{
  static unsigned long long toff;
  size_t msg_size;
  msg_size = sizeof (struct AudioMessage) + og->header_len + og->body_len;
  audio_message->header.size = htons ((uint16_t) msg_size);
  GNUNET_memcpy (&audio_message[1], og->header, og->header_len);
  GNUNET_memcpy (((char *) &audio_message[1]) + og->header_len, og->body, og->body_len);

  toff += msg_size;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending %u bytes of audio data (total: %llu)\n",
              (unsigned int) msg_size,
              toff);
#ifdef DEBUG_RECORD_PURE_OGG
  if (dump_pure_ogg)
    write_data ((const char *) &audio_message[1], og->header_len + og->body_len);
  else
#endif
    write_data ((const char *) audio_message, msg_size);
}

/**
 * Creates OPUS packets from PCM data
 */
static void
packetizer ()
{
  char *nbuf;
  size_t new_size;
  int32_t len;
  ogg_packet op;
  ogg_page og;

  while (transmit_buffer_length >= transmit_buffer_index + pcm_length)
  {
    GNUNET_memcpy (pcm_buffer,
	    &transmit_buffer[transmit_buffer_index],
	    pcm_length);
    transmit_buffer_index += pcm_length;
    len =
      opus_encode_float (enc, pcm_buffer, FRAME_SIZE, opus_data,
			 MAX_PAYLOAD_BYTES);

    if (len < 0)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  _("opus_encode_float() failed: %s. Aborting\n"),
                  opus_strerror (len));
      quit (5);
    }
    if (len > UINT16_MAX - sizeof (struct AudioMessage))
    {
      GNUNET_break (0);
      continue;
    }

    /* As per OggOpus spec, granule is calculated as if the audio
       had 48kHz sampling rate. */
    enc_granulepos += FRAME_SIZE * 48000 / SAMPLING_RATE;

    op.packet = (unsigned char *) opus_data;
    op.bytes = len;
    op.b_o_s = 0;
    op.e_o_s = 0;
    op.granulepos = enc_granulepos;
    op.packetno = packet_id++;
    ogg_stream_packetin (&os, &op);

    while (ogg_stream_flush_fill (&os, &og, PAGE_WATERLINE))
    {
      if (og.header_len + og.body_len > UINT16_MAX - sizeof (struct AudioMessage))
      {
        GNUNET_assert (0);
        continue;
      }
      write_page (&og);
    }
  }

  new_size = transmit_buffer_length - transmit_buffer_index;
  if (0 != new_size)
  {
    nbuf = pa_xmalloc (new_size);
    memmove (nbuf,
	     &transmit_buffer[transmit_buffer_index],
	     new_size);
    pa_xfree (transmit_buffer);
    transmit_buffer = nbuf;
  }
  else
  {
    pa_xfree (transmit_buffer);
    transmit_buffer = NULL;
  }
  transmit_buffer_index = 0;
  transmit_buffer_length = new_size;
}


/**
 * Pulseaudio callback when new data is available.
 */
static void
stream_read_callback (pa_stream * s,
		      size_t length,
		      void *userdata)
{
  const void *data;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Got %u/%d bytes of PCM data\n",
	      (unsigned int) length,
	      pcm_length);

  GNUNET_assert (NULL != s);
  GNUNET_assert (length > 0);
  if (stdio_event)
    mainloop_api->io_enable (stdio_event, PA_IO_EVENT_OUTPUT);

  if (pa_stream_peek (s, (const void **) &data, &length) < 0)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		_("pa_stream_peek() failed: %s\n"),
		pa_strerror (pa_context_errno (context)));
    quit (1);
    return;
  }
  GNUNET_assert (NULL != data);
  GNUNET_assert (length > 0);
  if (NULL != transmit_buffer)
  {
    transmit_buffer = pa_xrealloc (transmit_buffer,
				   transmit_buffer_length + length);
    GNUNET_memcpy (&transmit_buffer[transmit_buffer_length],
	    data,
	    length);
    transmit_buffer_length += length;
  }
  else
  {
    transmit_buffer = pa_xmalloc (length);
    GNUNET_memcpy (transmit_buffer, data, length);
    transmit_buffer_length = length;
    transmit_buffer_index = 0;
  }
  pa_stream_drop (s);
  packetizer ();
}


/**
 * Exit callback for SIGTERM and SIGINT
 */
static void
exit_signal_callback (pa_mainloop_api * m,
		      pa_signal_event * e,
		      int sig,
		      void *userdata)
{
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
	      _("Got signal, exiting.\n"));
  quit (1);
}


/**
 * Pulseaudio stream state callback
 */
static void
stream_state_callback (pa_stream * s, void *userdata)
{
  GNUNET_assert (NULL != s);

  switch (pa_stream_get_state (s))
  {
  case PA_STREAM_CREATING:
  case PA_STREAM_TERMINATED:
    break;
  case PA_STREAM_READY:
    {
      const pa_buffer_attr *a;
      char cmt[PA_CHANNEL_MAP_SNPRINT_MAX];
      char sst[PA_SAMPLE_SPEC_SNPRINT_MAX];

      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
		  _("Stream successfully created.\n"));

      if (!(a = pa_stream_get_buffer_attr (s)))
      {
	GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		    _("pa_stream_get_buffer_attr() failed: %s\n"),
		    pa_strerror (pa_context_errno
				 (pa_stream_get_context (s))));

      }
      else
      {
	GNUNET_log (GNUNET_ERROR_TYPE_INFO,
		    _("Buffer metrics: maxlength=%u, fragsize=%u\n"),
		    a->maxlength, a->fragsize);
      }
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
		  _("Using sample spec '%s', channel map '%s'.\n"),
		  pa_sample_spec_snprint (sst, sizeof (sst),
					  pa_stream_get_sample_spec (s)),
		  pa_channel_map_snprint (cmt, sizeof (cmt),
					  pa_stream_get_channel_map (s)));

      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
		  _("Connected to device %s (%u, %ssuspended).\n"),
		  pa_stream_get_device_name (s),
		  pa_stream_get_device_index (s),
		  pa_stream_is_suspended (s) ? "" : "not ");
    }
    break;
  case PA_STREAM_FAILED:
  default:
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		_("Stream error: %s\n"),
		pa_strerror (pa_context_errno (pa_stream_get_context (s))));
    quit (1);
  }
}


/**
 * Pulseaudio context state callback
 */
static void
context_state_callback (pa_context * c,
			void *userdata)
{
  GNUNET_assert (c);

  switch (pa_context_get_state (c))
  {
  case PA_CONTEXT_CONNECTING:
  case PA_CONTEXT_AUTHORIZING:
  case PA_CONTEXT_SETTING_NAME:
    break;
  case PA_CONTEXT_READY:
  {
    int r;
    pa_buffer_attr na;

    GNUNET_assert (!stream_in);
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
		_("Connection established.\n"));
    if (! (stream_in =
	   pa_stream_new (c, "GNUNET_VoIP recorder", &sample_spec, NULL)))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		  _("pa_stream_new() failed: %s\n"),
		  pa_strerror (pa_context_errno (c)));
      goto fail;
    }
    pa_stream_set_state_callback (stream_in, &stream_state_callback, NULL);
    pa_stream_set_read_callback (stream_in, &stream_read_callback, NULL);
    memset (&na, 0, sizeof (na));
    na.maxlength = UINT32_MAX;
    na.fragsize = pcm_length;
    if ((r = pa_stream_connect_record (stream_in, NULL, &na,
				       PA_STREAM_ADJUST_LATENCY)) < 0)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		  _("pa_stream_connect_record() failed: %s\n"),
		  pa_strerror (pa_context_errno (c)));
      goto fail;
    }

    break;
  }
  case PA_CONTEXT_TERMINATED:
    quit (0);
    break;
  case PA_CONTEXT_FAILED:
  default:
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		_("Connection failure: %s\n"),
		pa_strerror (pa_context_errno (c)));
    goto fail;
  }
  return;

fail:
  quit (1);
}


/**
 * Pulsaudio init
 */
static void
pa_init ()
{
  int r;
  int i;

  if (!pa_sample_spec_valid (&sample_spec))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		_("Wrong Spec\n"));
  }
  /* set up main record loop */
  if (!(m = pa_mainloop_new ()))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		_("pa_mainloop_new() failed.\n"));
  }
  mainloop_api = pa_mainloop_get_api (m);

  /* listen to signals */
  r = pa_signal_init (mainloop_api);
  GNUNET_assert (r == 0);
  pa_signal_new (SIGINT, &exit_signal_callback, NULL);
  pa_signal_new (SIGTERM, &exit_signal_callback, NULL);

  /* connect to the main pulseaudio context */

  if (!(context = pa_context_new (mainloop_api, "GNUNET VoIP")))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		_("pa_context_new() failed.\n"));
  }
  pa_context_set_state_callback (context, &context_state_callback, NULL);
  if (pa_context_connect (context, NULL, 0, NULL) < 0)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		_("pa_context_connect() failed: %s\n"),
		pa_strerror (pa_context_errno (context)));
  }
  if (pa_mainloop_run (m, &i) < 0)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		_("pa_mainloop_run() failed.\n"));
  }
}


/**
 * OPUS init
 */
static void
opus_init ()
{
  int err;

  pcm_length = FRAME_SIZE * CHANNELS * sizeof (float);
  pcm_buffer = pa_xmalloc (pcm_length);
  opus_data = GNUNET_malloc (MAX_PAYLOAD_BYTES);
  enc = opus_encoder_create (SAMPLING_RATE,
			     CHANNELS,
			     CONV_OPUS_APP_TYPE,
			     &err);
  opus_encoder_ctl (enc,
		    OPUS_SET_PACKET_LOSS_PERC (CONV_OPUS_PACKET_LOSS_PERCENTAGE));
  opus_encoder_ctl (enc,
		    OPUS_SET_COMPLEXITY (CONV_OPUS_ENCODING_COMPLEXITY));
  opus_encoder_ctl (enc,
		    OPUS_SET_INBAND_FEC (CONV_OPUS_INBAND_FEC));
  opus_encoder_ctl (enc,
		    OPUS_SET_SIGNAL (CONV_OPUS_SIGNAL));
}

static void
ogg_init ()
{
  int serialno;
  struct OpusHeadPacket headpacket;
  struct OpusCommentsPacket *commentspacket;
  size_t commentspacket_len;

  serialno = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_STRONG, 0x7FFFFFFF);

  /*Initialize Ogg stream struct*/
  if (-1 == ogg_stream_init (&os, serialno))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		_("ogg_stream_init() failed.\n"));
    exit (3);
  }

  packet_id = 0;

  /*Write header*/
  {
    ogg_packet op;
    ogg_page og;
    const char *opusver;
    int vendor_length;

    GNUNET_memcpy (headpacket.magic, "OpusHead", 8);
    headpacket.version = 1;
    headpacket.channels = CHANNELS;
    headpacket.preskip = GNUNET_htole16 (0);
    headpacket.sampling_rate = GNUNET_htole32 (SAMPLING_RATE);
    headpacket.gain = GNUNET_htole16 (0);
    headpacket.channel_mapping = 0; /* Mono or stereo */

    op.packet = (unsigned char *) &headpacket;
    op.bytes = sizeof (headpacket);
    op.b_o_s = 1;
    op.e_o_s = 0;
    op.granulepos = 0;
    op.packetno = packet_id++;
    ogg_stream_packetin (&os, &op);

    /* Head packet must be alone on its page */
    while (ogg_stream_flush (&os, &og))
    {
      write_page (&og);
    }

    commentspacket_len = sizeof (*commentspacket);
    opusver = opus_get_version_string ();
    vendor_length = strlen (opusver);
    commentspacket_len += vendor_length;
    commentspacket_len += sizeof (uint32_t);

    commentspacket = (struct OpusCommentsPacket *) malloc (commentspacket_len);
    if (NULL == commentspacket)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		  _("Failed to allocate %u bytes for second packet\n"),
                  (unsigned int) commentspacket_len);
      exit (5);
    }

    GNUNET_memcpy (commentspacket->magic, "OpusTags", 8);
    commentspacket->vendor_length = GNUNET_htole32 (vendor_length);
    GNUNET_memcpy (&commentspacket[1], opusver, vendor_length);
    *(uint32_t *) &((char *) &commentspacket[1])[vendor_length] = \
        GNUNET_htole32 (0); /* no tags */

    op.packet = (unsigned char *) commentspacket;
    op.bytes = commentspacket_len;
    op.b_o_s = 0;
    op.e_o_s = 0;
    op.granulepos = 0;
    op.packetno = packet_id++;
    ogg_stream_packetin (&os, &op);

    /* Comment packets must not be mixed with audio packets on their pages */
    while (ogg_stream_flush (&os, &og))
    {
      write_page (&og);
    }

    free (commentspacket);
  }
}

/**
 * The main function for the record helper.
 *
 * @param argc number of arguments from the command line
 * @param argv command line arguments
 * @return 0 ok, 1 on error
 */
int
main (int argc, char *argv[])
{
  GNUNET_assert (GNUNET_OK ==
		 GNUNET_log_setup ("gnunet-helper-audio-record",
				   "WARNING",
				   NULL));
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Audio source starts\n");
  audio_message = GNUNET_malloc (UINT16_MAX);
  audio_message->header.type = htons (GNUNET_MESSAGE_TYPE_CONVERSATION_AUDIO);

#ifdef DEBUG_RECORD_PURE_OGG
  dump_pure_ogg = getenv ("GNUNET_RECORD_PURE_OGG") ? 1 : 0;
#endif
  ogg_init ();
  opus_init ();
  pa_init ();
  return 0;
}