chiark / gitweb /
speaker protocol redesign to cope with libao re-opening
[disorder] / server / speaker.h
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cf714d85 1/*
2 * This file is part of DisOrder
3 * Copyright (C) 2005, 2006, 2007 Richard Kettlewell
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
18 * USA
19 */
20/** @file server/speaker.h
21 * @brief Speaker process
22 */
23#ifndef SPEAKER_H
24#define SPEAKER_H
25
26#ifdef WORDS_BIGENDIAN
27# define MACHINE_AO_FMT AO_FMT_BIG
28#else
29# define MACHINE_AO_FMT AO_FMT_LITTLE
30#endif
31
5a7c42a8 32/** @brief Minimum number of frames to try to play at once
cf714d85 33 *
5a7c42a8 34 * The main loop will only attempt to play any audio when this many
35 * frames are available (or the current track has reached the end).
36 * The actual number of frames it attempts to play will often be
37 * larger than this (up to three times).
cf714d85 38 *
39 * For ALSA we request a buffer of three times this size and set the low
40 * watermark to this amount. The goal is then to keep between 1 and 3 times
41 * this many frames in play.
42 *
5a7c42a8 43 * For other we attempt to play up to three times this many frames per
cf714d85 44 * shot. In practice we will often only send much less than this.
45 */
46#define FRAMES 4096
47
48/** @brief Bytes to send per network packet
49 *
50 * Don't make this too big or arithmetic will start to overflow.
51 */
52#define NETWORK_BYTES (1024+sizeof(struct rtp_header))
53
54/** @brief Maximum RTP playahead (ms) */
55#define RTP_AHEAD_MS 1000
56
57/** @brief Maximum number of FDs to poll for */
58#define NFDS 256
59
60/** @brief Track structure
61 *
62 * Known tracks are kept in a linked list. Usually there will be at most two
63 * of these but rearranging the queue can cause there to be more.
64 */
65struct track {
6d2d327c
RK
66 /** @brief Next track */
67 struct track *next;
68
69 /** @brief Input file descriptor */
cf714d85 70 int fd; /* input FD */
6d2d327c
RK
71
72 /** @brief Track ID */
73 char id[24];
74
75 /** @brief Start position of data in buffer */
76 size_t start;
77
78 /** @brief Number of bytes of data in buffer */
79 size_t used;
80
81 /** @brief Set @c fd is at EOF */
82 int eof;
83
84 /** @brief Total number of frames played */
85 unsigned long long played;
86
87 /** @brief Slot in @ref fds */
88 int slot;
89
90 /** @brief Input buffer
91 *
92 * 1Mbyte is enough for nearly 6s of 44100Hz 16-bit stereo
93 */
94 char buffer[1048576];
cf714d85 95};
96
97/** @brief Structure of a backend */
98struct speaker_backend {
99 /** @brief Which backend this is
100 *
101 * @c -1 terminates the list.
102 */
103 int backend;
104
105 /** @brief Flags
106 *
6d2d327c 107 * This field is currently not used and must be 0.
cf714d85 108 */
109 unsigned flags;
cf714d85 110
111 /** @brief Initialization
112 *
113 * Called once at startup. This is responsible for one-time setup
114 * operations, for instance opening a network socket to transmit to.
115 *
116 * When writing to a native sound API this might @b not imply opening the
117 * native sound device - that might be done by @c activate below.
118 */
119 void (*init)(void);
120
121 /** @brief Activation
122 * @return 0 on success, non-0 on error
123 *
124 * Called to activate the output device.
125 *
5a7c42a8 126 * On input @ref device_state may be anything. If it is @ref
127 * device_open then the device is already open but might be using
128 * the wrong sample format. The device should be reconfigured to
129 * use the right sample format.
130 *
131 * If it is @ref device_error then a retry is underway and an
132 * attempt to recover or re-open the device (with the right sample
133 * format) should be made.
134 *
135 * If it is @ref device_closed then the device should be opened with
136 * the right sample format.
137 *
5a7c42a8 138 * Some devices are effectively always open and have no error state,
139 * in which case this callback can be NULL. In this case @ref
140 * FIXED_FORMAT must be set. Note that @ref device_state still
0e4472a0 141 * switches between @ref device_open and @ref device_closed in this
5a7c42a8 142 * case.
cf714d85 143 */
5a7c42a8 144 void (*activate)(void);
cf714d85 145
146 /** @brief Play sound
147 * @param frames Number of frames to play
148 * @return Number of frames actually played
5a7c42a8 149 *
150 * If an error occurs (and it is not immediately recovered) this
151 * should set @ref device_state to @ref device_error.
cf714d85 152 */
153 size_t (*play)(size_t frames);
154
155 /** @brief Deactivation
156 *
5a7c42a8 157 * Called to deactivate the sound device. This is the inverse of @c
158 * activate above.
159 *
160 * For sound devices that are open all the time and have no error
161 * state, this callback can be NULL. Note that @ref device_state
0e4472a0 162 * still switches between @ref device_open and @ref device_closed in
5a7c42a8 163 * this case.
cf714d85 164 */
165 void (*deactivate)(void);
166
167 /** @brief Called before poll()
168 *
5a7c42a8 169 * Called before the call to poll(). Should call addfd() to update
170 * the FD array and stash the slot number somewhere safe. This will
171 * only be called if @ref device_state = @ref device_open.
cf714d85 172 */
173 void (*beforepoll)(void);
174
175 /** @brief Called after poll()
5a7c42a8 176 * @return 1 if output device ready for play, 0 otherwise
cf714d85 177 *
5a7c42a8 178 * Called after the call to poll(). This will only be called if
179 * @ref device_state = @ref device_open.
cf714d85 180 *
5a7c42a8 181 * The return value should be 1 if the device was ready to play, or
182 * 0 if it was not.
cf714d85 183 */
5a7c42a8 184 int (*ready)(void);
cf714d85 185};
186
5a7c42a8 187/** @brief Possible device states */
188enum device_states {
189 /** @brief The device is closed */
190 device_closed,
191
192 /** @brief The device is open and ready to receive sound
193 *
194 * The current device sample format is potentially part of this state.
195 */
196 device_open,
197
198 /** @brief An error has occurred on the device
199 *
200 * This state is used to ensure that a small interval is left
201 * between retrying the device. If errors just set @ref
202 * device_closed then the main loop would busy-wait on broken output
203 * devices.
204 *
205 * The current device sample format is potentially part of this state.
206 */
207 device_error
208};
cf714d85 209
5a7c42a8 210extern enum device_states device_state;
5a7c42a8 211extern struct track *tracks;
cf714d85 212extern struct track *playing;
213
1c3f1e73 214extern const struct speaker_backend network_backend;
215extern const struct speaker_backend alsa_backend;
216extern const struct speaker_backend command_backend;
217
218extern struct pollfd fds[NFDS];
219extern int fdno;
6d2d327c 220extern size_t bpf;
1c3f1e73 221extern int idled;
222
223int addfd(int fd, int events);
1c3f1e73 224void abandon(void);
225
cf714d85 226#endif /* SPEAKER_H */
227
228/*
229Local Variables:
230c-basic-offset:2
231comment-column:40
232fill-column:79
233indent-tabs-mode:nil
234End:
235*/