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
|
#include "../include/sound.hpp"
#include <stdlib.h>
#include <stdio.h>
#define ALSA_PCM_NEW_HW_PARAMS_API
#include <alsa/asoundlib.h>
int sound_device_get_by_name(SoundDevice *device, const char *name, unsigned int num_channels, unsigned int period_frame_size) {
int rc;
snd_pcm_t *handle;
rc = snd_pcm_open(&handle, name, SND_PCM_STREAM_CAPTURE, 0);
if(rc < 0) {
fprintf(stderr, "unable to open pcm device 'default', reason: %s\n", snd_strerror(rc));
return rc;
}
snd_pcm_hw_params_t *params;
snd_pcm_hw_params_alloca(¶ms);
// Fill the params with default values
snd_pcm_hw_params_any(handle, params);
// Interleaved mode
snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);
// Signed 16--bit little-endian format
snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE);
snd_pcm_hw_params_set_channels(handle, params, num_channels);
// 44100 bits/second samling rate (CD quality)
unsigned int val = 44100;
int dir;
snd_pcm_hw_params_set_rate_near(handle, params, &val, &dir);
snd_pcm_uframes_t frames = period_frame_size;
snd_pcm_hw_params_set_period_size_near(handle, params, &frames, &dir);
// Write the parmeters to the driver
rc = snd_pcm_hw_params(handle, params);
if(rc < 0) {
fprintf(stderr, "unable to set hw parameters, reason: %s\n", snd_strerror(rc));
snd_pcm_close(handle);
return rc;
}
// Use a buffer large enough to hold one period
snd_pcm_hw_params_get_period_size(params, &frames, &dir);
int buffer_size = frames * 2 * num_channels; // 2 bytes/sample, @num_channels channels
char *buffer = (char*)malloc(buffer_size);
if(!buffer) {
fprintf(stderr, "failed to allocate buffer for audio\n");
snd_pcm_close(handle);
return -1;
}
device->handle = (void*)handle;
device->buffer = buffer;
device->buffer_size = buffer_size;
device->frames = frames;
return 0;
}
int sound_device_close(SoundDevice *device) {
/* TODO: Is this also needed in @sound_device_get_by_name on failure? */
snd_pcm_drain((snd_pcm_t*)device->handle);
snd_pcm_close((snd_pcm_t*)device->handle);
free(device->buffer);
}
int sound_device_read_next_chunk(SoundDevice *device, char **buffer) {
int rc = snd_pcm_readi((snd_pcm_t*)device->handle, device->buffer, device->frames);
if (rc == -EPIPE) {
/* overrun */
fprintf(stderr, "overrun occured\n");
snd_pcm_prepare((snd_pcm_t*)device->handle);
return 0;
} else if(rc < 0) {
fprintf(stderr, "failed to read from sound device, reason: %s\n", snd_strerror(rc));
return rc;
} else if (rc != (int)device->frames) {
fprintf(stderr, "short read, read %d frames\n", rc);
}
*buffer = device->buffer;
return rc;
}
|
