1 |
/*************************************************************************** |
2 |
* * |
3 |
* LinuxSampler - modular, streaming capable sampler * |
4 |
* * |
5 |
* Copyright (C) 2003 by Benno Senoner and Christian Schoenebeck * |
6 |
* * |
7 |
* This program is free software; you can redistribute it and/or modify * |
8 |
* it under the terms of the GNU General Public License as published by * |
9 |
* the Free Software Foundation; either version 2 of the License, or * |
10 |
* (at your option) any later version. * |
11 |
* * |
12 |
* This program is distributed in the hope that it will be useful, * |
13 |
* but WITHOUT ANY WARRANTY; without even the implied warranty of * |
14 |
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * |
15 |
* GNU General Public License for more details. * |
16 |
* * |
17 |
* You should have received a copy of the GNU General Public License * |
18 |
* along with this program; if not, write to the Free Software * |
19 |
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, * |
20 |
* MA 02111-1307 USA * |
21 |
***************************************************************************/ |
22 |
|
23 |
#ifndef __LS_AUDIOOUTPUTDEVICE_H__ |
24 |
#define __LS_AUDIOOUTPUTDEVICE_H__ |
25 |
|
26 |
#include <set> |
27 |
#include <vector> |
28 |
#include <stdexcept> |
29 |
|
30 |
#include "../common/global.h" |
31 |
#include "../common/LinuxSamplerException.h" |
32 |
#include "../engines/common/Engine.h" |
33 |
#include "AudioChannel.h" |
34 |
|
35 |
namespace LinuxSampler { |
36 |
|
37 |
// just symbol prototyping |
38 |
class Engine; |
39 |
|
40 |
/** Abstract base class for audio output drivers in LinuxSampler |
41 |
* |
42 |
* This class will be derived by specialized classes which implement the |
43 |
* connection to a specific audio output system (e.g. Alsa, Jack, |
44 |
* CoreAudio). |
45 |
*/ |
46 |
class AudioOutputDevice { |
47 |
public: |
48 |
|
49 |
///////////////////////////////////////////////////////////////// |
50 |
// abstract methods |
51 |
// (these have to be implemented by the descendant) |
52 |
|
53 |
/** |
54 |
* Start playback of audio signal on the audio device. It's the |
55 |
* responsibility of the implementing audio device to call the |
56 |
* RenderAudio(uint Samples) method of all connected engines. |
57 |
* This will cause the engines to continue to render 'Samples' |
58 |
* number of audio sample points and the engines will |
59 |
* automatically add their audio signals to the audio buffers of |
60 |
* the audio channels of this audio device. So the implementing |
61 |
* audio device just has to access the buffers of it's audio |
62 |
* channels. |
63 |
* |
64 |
* @throws AudioOutputException if playback can not be started |
65 |
* @see AudioChannel |
66 |
*/ |
67 |
virtual void Play() = 0; |
68 |
|
69 |
/** |
70 |
* Returns true if the audio device is currently playing back. |
71 |
*/ |
72 |
virtual bool IsPlaying() = 0; |
73 |
|
74 |
/** |
75 |
* Stop playback of audio signal on the audio device. The |
76 |
* implementing audio device will stop calling the RenderAudio() |
77 |
* method of all connected engines and close it's connection to |
78 |
* audio output system. |
79 |
*/ |
80 |
virtual void Stop() = 0; |
81 |
|
82 |
/** |
83 |
* This method will usually be called by the sampler engines that |
84 |
* are connected to this audio device to inform the audio device |
85 |
* how much audio channels the engine(s) need. It's the |
86 |
* responsibility of the audio device to offer that amount of |
87 |
* audio channels - again: this is not an option this is a must! |
88 |
* The engines will assume to be able to access those audio |
89 |
* channels right after. If the audio driver is not able to offer |
90 |
* that much channels, it can simply create mix channels which |
91 |
* are then just mixed to the 'real' audio channels. See |
92 |
* AudioChannel.h for details about channels and mix channels. |
93 |
* |
94 |
* @param Channels - amount of output channels required by |
95 |
* a sampler engine |
96 |
* @throws AudioOutputException if desired amount of channels |
97 |
* cannot be offered |
98 |
* @see AudioChannel |
99 |
*/ |
100 |
virtual void AcquireChannels(uint Channels) = 0; |
101 |
|
102 |
/** |
103 |
* Maximum amount of sample points the implementing audio |
104 |
* device will ever demand the sampler engines to write in one |
105 |
* fragment cycle / period. Simple audio device drivers usually |
106 |
* have a fixed fragment size, so those devices just would return |
107 |
* the fragment size in this method. |
108 |
* |
109 |
* @returns max. amount of sample points ever |
110 |
*/ |
111 |
virtual uint MaxSamplesPerCycle() = 0; |
112 |
|
113 |
/** |
114 |
* Playback samplerate the audio device uses. The sampler engines |
115 |
* currently assume this to be a constant value for the whole |
116 |
* life time of an instance of the implementing audio device. |
117 |
* |
118 |
* @returns sample rate in Hz |
119 |
*/ |
120 |
virtual uint SampleRate() = 0; |
121 |
|
122 |
|
123 |
|
124 |
///////////////////////////////////////////////////////////////// |
125 |
// normal methods |
126 |
// (usually not to be overriden by descendant) |
127 |
|
128 |
/** |
129 |
* Connect given sampler engine to this audio output device. The |
130 |
* engine will be added to the Engines container of this audio |
131 |
* device and the engine will also automatically be informed |
132 |
* about the connection. |
133 |
* |
134 |
* @param pEngine - sampler engine |
135 |
*/ |
136 |
void Connect(Engine* pEngine); |
137 |
|
138 |
/** |
139 |
* Disconnect given sampler engine from this audio output device. |
140 |
* Removes given sampler engine reference from the Engines |
141 |
* container of this audio device. |
142 |
* |
143 |
* @param pEngine - sampler engine |
144 |
*/ |
145 |
void Disconnect(Engine* pEngine); |
146 |
|
147 |
/** |
148 |
* Returns audio channel with index \a ChannelIndex or NULL if |
149 |
* index out of bounds. |
150 |
*/ |
151 |
AudioChannel* Channel(uint ChannelIndex); |
152 |
|
153 |
protected: |
154 |
std::set<Engine*> Engines; ///< All sampler engines that are connected to the audio output device. |
155 |
std::vector<AudioChannel*> Channels; ///< All audio channels of the audio output device. This is just a container; the descendant has to create channels by himself. |
156 |
|
157 |
/** |
158 |
* This method should be called by the AudioOutputDevice |
159 |
* descendant to let all connected engines proceed to render the |
160 |
* given amount of sample points. The engines will place their |
161 |
* calculated audio data by themselfes into the buffers of the |
162 |
* respective AudioChannel objects, so the implementing audio |
163 |
* output device just has to copy the AudioChannel buffers to |
164 |
* the output buffer(s) of its audio system. |
165 |
* |
166 |
* @returns 0 on success or the last error return code of one |
167 |
* engine |
168 |
*/ |
169 |
int RenderAudio(uint Samples); |
170 |
|
171 |
/** |
172 |
* This can be called as an alternative to RenderAudio() for |
173 |
* just writing silence to the audio output buffers and not |
174 |
* calling the connected sampler engines for rendering audio, so |
175 |
* to provide a method to stop playback if the used audio output |
176 |
* system doesn't provide a better way. |
177 |
* |
178 |
* @returns 0 on success |
179 |
*/ |
180 |
int RenderSilence(uint Samples); |
181 |
}; |
182 |
|
183 |
/** |
184 |
* Audio output exception that should be thrown by the AudioOutputDevice |
185 |
* descendants in case initialization of the audio output system failed |
186 |
* (which should be done in the constructor of the AudioOutputDevice |
187 |
* descendant). |
188 |
*/ |
189 |
class AudioOutputException : public LinuxSamplerException { |
190 |
public: |
191 |
AudioOutputException(const std::string& msg) : LinuxSamplerException(msg) {} |
192 |
}; |
193 |
} |
194 |
|
195 |
#endif // __LS_AUDIOOUTPUTDEVICE_H__ |