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
|
/*
* Copyright (C) 2003-2013 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*
* ALSA code based on an example by Paul Davis released under GPL here:
* http://equalarea.com/paul/alsa-audio.html
* and one by Matthias Nagorni, also GPL, here:
* http://alsamodular.sourceforge.net/alsa_programming_howto.html
*/
#include "config.h"
#include "AlsaInputPlugin.hxx"
#include "InputPlugin.hxx"
#include "InputStream.hxx"
#include "util/Domain.hxx"
#include "util/Error.hxx"
#include "util/StringUtil.hxx"
#include "Log.hxx"
#include <alsa/asoundlib.h>
static constexpr Domain alsa_input_domain("alsa");
static constexpr const char *default_device = "hw:0,0";
// this value chosen to balance between limiting latency and avoiding stutter
static constexpr int max_frames_to_buffer = 64;
// the following defaults are because the PcmDecoderPlugin forces CD format
static constexpr snd_pcm_format_t default_format = SND_PCM_FORMAT_S16;
static constexpr int default_channels = 2; // stereo
static constexpr unsigned int default_rate = 44100; // cd quality
struct AlsaInputStream {
InputStream base;
snd_pcm_t *capture_handle;
size_t frame_size;
size_t max_bytes_to_read;
AlsaInputStream(const char *uri, Mutex &mutex, Cond &cond,
snd_pcm_t *handle)
:base(input_plugin_alsa, uri, mutex, cond),
capture_handle(handle) {
frame_size = snd_pcm_format_width(default_format) / 8 * default_channels;
max_bytes_to_read = max_frames_to_buffer * frame_size;
base.mime = strdup("audio/x-mpd-cdda-pcm");
base.seekable = false;
base.size = -1;
base.ready = true;
}
~AlsaInputStream() {
snd_pcm_close(capture_handle);
}
};
static InputStream *
alsa_input_open(const char *uri, Mutex &mutex, Cond &cond, Error &error)
{
int err;
// check uri is appropriate for alsa input
if (!StringStartsWith(uri, "alsa://"))
return nullptr;
const char *device = uri + 7;
if (device[0] == '\0')
device = default_device;
snd_pcm_t *capture_handle;
if ((err = snd_pcm_open(&capture_handle, device,
SND_PCM_STREAM_CAPTURE, 0)) < 0) {
error.Format(alsa_input_domain, "Failed to open device: %s (%s)", device, snd_strerror(err));
return nullptr;
}
snd_pcm_hw_params_t *hw_params;
if ((err = snd_pcm_hw_params_malloc(&hw_params)) < 0) {
error.Format(alsa_input_domain, "Cannot allocate hardware parameter structure (%s)", snd_strerror(err));
snd_pcm_close(capture_handle);
return nullptr;
}
if ((err = snd_pcm_hw_params_any(capture_handle, hw_params)) < 0) {
error.Format(alsa_input_domain, "Cannot initialize hardware parameter structure (%s)", snd_strerror(err));
snd_pcm_hw_params_free(hw_params);
snd_pcm_close(capture_handle);
return nullptr;
}
if ((err = snd_pcm_hw_params_set_access(capture_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
error.Format(alsa_input_domain, "Cannot set access type (%s)", snd_strerror (err));
snd_pcm_hw_params_free (hw_params);
snd_pcm_close(capture_handle);
return nullptr;
}
if ((err = snd_pcm_hw_params_set_format(capture_handle, hw_params, default_format)) < 0) {
snd_pcm_hw_params_free(hw_params);
snd_pcm_close(capture_handle);
error.Format(alsa_input_domain, "Cannot set sample format (%s)", snd_strerror (err));
return nullptr;
}
if ((err = snd_pcm_hw_params_set_channels(capture_handle, hw_params, default_channels)) < 0) {
snd_pcm_hw_params_free(hw_params);
snd_pcm_close(capture_handle);
error.Format(alsa_input_domain, "Cannot set channels (%s)", snd_strerror (err));
return nullptr;
}
if ((err = snd_pcm_hw_params_set_rate(capture_handle, hw_params, default_rate, 0)) < 0) {
snd_pcm_hw_params_free(hw_params);
snd_pcm_close(capture_handle);
error.Format(alsa_input_domain, "Cannot set sample rate (%s)", snd_strerror (err));
return nullptr;
}
if ((err = snd_pcm_hw_params(capture_handle, hw_params)) < 0) {
error.Format(alsa_input_domain, "Cannot set parameters (%s)", snd_strerror (err));
snd_pcm_hw_params_free(hw_params);
snd_pcm_close(capture_handle);
return nullptr;
}
snd_pcm_hw_params_free (hw_params);
// clear any data already in the PCM buffer
if ((err = snd_pcm_drop(capture_handle)) < 0) {
error.Format(alsa_input_domain, "Cannot clear PCM buffer (%s)", snd_strerror (err));
snd_pcm_hw_params_free(hw_params);
snd_pcm_close(capture_handle);
return nullptr;
}
AlsaInputStream *ais = new AlsaInputStream(uri, mutex, cond, capture_handle);
return &ais->base;
}
static void
alsa_input_close(InputStream *is)
{
AlsaInputStream *ais = (AlsaInputStream*) is;
delete ais;
}
static size_t
alsa_input_read(InputStream *is, void *ptr, size_t size,
gcc_unused Error &error)
{
AlsaInputStream *ais = (AlsaInputStream*) is;
int num_frames = max_frames_to_buffer;
if (size < ais->max_bytes_to_read)
// calculate number of whole frames that will fit in size bytes
num_frames = size / ais->frame_size;
int ret;
while ((ret = snd_pcm_readi(ais->capture_handle, ptr,
num_frames)) < 0) {
snd_pcm_prepare(ais->capture_handle);
LogDebug(alsa_input_domain, "Buffer Overrun");
}
size_t nbytes = ret == max_frames_to_buffer
? ais->max_bytes_to_read
: ret * ais->frame_size;
is->offset += nbytes;
return nbytes;
}
static bool
alsa_input_eof(gcc_unused InputStream *is)
{
return false;
};
const struct InputPlugin input_plugin_alsa = {
.name = "alsa",
.init = nullptr,
.finish = nullptr,
.open = alsa_input_open,
.close = alsa_input_close,
.check = nullptr,
.update = nullptr,
.tag = nullptr,
.available = nullptr,
.read = alsa_input_read,
.eof = alsa_input_eof,
.seek = nullptr
};
|
