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
|
/*
* Copyright 2003-2020 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.
*/
#include "OpenALOutputPlugin.hxx"
#include "../OutputAPI.hxx"
#include "util/RuntimeError.hxx"
#include <unistd.h>
#ifndef __APPLE__
#include <AL/al.h>
#include <AL/alc.h>
#else
#include <OpenAL/al.h>
#include <OpenAL/alc.h>
#endif
class OpenALOutput final : AudioOutput {
/* should be enough for buffer size = 2048 */
static constexpr unsigned NUM_BUFFERS = 16;
const char *device_name;
ALCdevice *device;
ALCcontext *context;
ALuint buffers[NUM_BUFFERS];
unsigned filled;
ALuint source;
ALenum format;
ALuint frequency;
OpenALOutput(const ConfigBlock &block);
public:
static AudioOutput *Create(EventLoop &,
const ConfigBlock &block) {
return new OpenALOutput(block);
}
private:
void Open(AudioFormat &audio_format) override;
void Close() noexcept override;
gcc_pure
std::chrono::steady_clock::duration Delay() const noexcept override {
return filled < NUM_BUFFERS || HasProcessed()
? std::chrono::steady_clock::duration::zero()
/* we don't know exactly how long we must wait
for the next buffer to finish, so this is a
random guess: */
: std::chrono::milliseconds(50);
}
size_t Play(const void *chunk, size_t size) override;
void Cancel() noexcept override;
private:
gcc_pure
ALint GetSourceI(ALenum param) const noexcept {
ALint value;
alGetSourcei(source, param, &value);
return value;
}
gcc_pure
bool HasProcessed() const noexcept {
return GetSourceI(AL_BUFFERS_PROCESSED) > 0;
}
gcc_pure
bool IsPlaying() const noexcept {
return GetSourceI(AL_SOURCE_STATE) == AL_PLAYING;
}
/**
* Throws on error.
*/
void SetupContext();
};
static ALenum
openal_audio_format(AudioFormat &audio_format)
{
/* note: cannot map SampleFormat::S8 to AL_FORMAT_STEREO8 or
AL_FORMAT_MONO8 since OpenAL expects unsigned 8 bit
samples, while MPD uses signed samples */
switch (audio_format.format) {
case SampleFormat::S16:
if (audio_format.channels == 2)
return AL_FORMAT_STEREO16;
if (audio_format.channels == 1)
return AL_FORMAT_MONO16;
/* fall back to mono */
audio_format.channels = 1;
return openal_audio_format(audio_format);
default:
/* fall back to 16 bit */
audio_format.format = SampleFormat::S16;
return openal_audio_format(audio_format);
}
}
inline void
OpenALOutput::SetupContext()
{
device = alcOpenDevice(device_name);
if (device == nullptr)
throw FormatRuntimeError("Error opening OpenAL device \"%s\"",
device_name);
context = alcCreateContext(device, nullptr);
if (context == nullptr) {
alcCloseDevice(device);
throw FormatRuntimeError("Error creating context for \"%s\"",
device_name);
}
}
OpenALOutput::OpenALOutput(const ConfigBlock &block)
:AudioOutput(0),
device_name(block.GetBlockValue("device"))
{
if (device_name == nullptr)
device_name = alcGetString(nullptr,
ALC_DEFAULT_DEVICE_SPECIFIER);
}
void
OpenALOutput::Open(AudioFormat &audio_format)
{
format = openal_audio_format(audio_format);
SetupContext();
alcMakeContextCurrent(context);
alGenBuffers(NUM_BUFFERS, buffers);
if (alGetError() != AL_NO_ERROR)
throw std::runtime_error("Failed to generate buffers");
alGenSources(1, &source);
if (alGetError() != AL_NO_ERROR) {
alDeleteBuffers(NUM_BUFFERS, buffers);
throw std::runtime_error("Failed to generate source");
}
filled = 0;
frequency = audio_format.sample_rate;
}
void
OpenALOutput::Close() noexcept
{
alcMakeContextCurrent(context);
alDeleteSources(1, &source);
alDeleteBuffers(NUM_BUFFERS, buffers);
alcDestroyContext(context);
alcCloseDevice(device);
}
size_t
OpenALOutput::Play(const void *chunk, size_t size)
{
if (alcGetCurrentContext() != context)
alcMakeContextCurrent(context);
ALuint buffer;
if (filled < NUM_BUFFERS) {
/* fill all buffers */
buffer = buffers[filled];
filled++;
} else {
/* wait for processed buffer */
while (!HasProcessed())
usleep(10);
alSourceUnqueueBuffers(source, 1, &buffer);
}
alBufferData(buffer, format, chunk, size, frequency);
alSourceQueueBuffers(source, 1, &buffer);
if (!IsPlaying())
alSourcePlay(source);
return size;
}
void
OpenALOutput::Cancel() noexcept
{
filled = 0;
alcMakeContextCurrent(context);
alSourceStop(source);
/* force-unqueue all buffers */
alSourcei(source, AL_BUFFER, 0);
filled = 0;
}
const struct AudioOutputPlugin openal_output_plugin = {
"openal",
nullptr,
OpenALOutput::Create,
nullptr,
};
|
