| 1 | /* |
| 2 | * This file is part of DisOrder. |
| 3 | * Copyright (C) 2009 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 3 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, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU 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, see <http://www.gnu.org/licenses/>. |
| 17 | */ |
| 18 | /** @file lib/uaudio-thread.c |
| 19 | * @brief Background thread for audio processing */ |
| 20 | #include "common.h" |
| 21 | |
| 22 | #include <pthread.h> |
| 23 | #include <unistd.h> |
| 24 | |
| 25 | #include "uaudio.h" |
| 26 | #include "log.h" |
| 27 | #include "mem.h" |
| 28 | |
| 29 | /** @brief Number of buffers |
| 30 | * |
| 31 | * Must be at least 2 and should normally be at least 3. We maintain multiple |
| 32 | * buffers so that we can read new data into one while the previous is being |
| 33 | * played. |
| 34 | */ |
| 35 | #define UAUDIO_THREAD_BUFFERS 4 |
| 36 | |
| 37 | /** @brief Buffer data structure */ |
| 38 | struct uaudio_buffer { |
| 39 | /** @brief Pointer to sample data */ |
| 40 | void *samples; |
| 41 | |
| 42 | /** @brief Count of samples */ |
| 43 | size_t nsamples; |
| 44 | }; |
| 45 | |
| 46 | /** @brief Input buffers |
| 47 | * |
| 48 | * This is actually a ring buffer, managed by @ref uaudio_collect_buffer and |
| 49 | * @ref uaudio_play_buffer. |
| 50 | * |
| 51 | * Initially both pointers are 0. Whenever the pointers are equal, we |
| 52 | * interpreted this as meaning that there is no data stored at all. A |
| 53 | * consequence of this is that maximal occupancy is when the collect point is |
| 54 | * just before the play point, so at least one buffer is always empty (hence it |
| 55 | * being good for @ref UAUDIO_THREAD_BUFFERS to be at least 3). |
| 56 | */ |
| 57 | static struct uaudio_buffer uaudio_buffers[UAUDIO_THREAD_BUFFERS]; |
| 58 | |
| 59 | /** @brief Buffer to read into */ |
| 60 | static unsigned uaudio_collect_buffer; |
| 61 | |
| 62 | /** @brief Buffer to play from */ |
| 63 | static unsigned uaudio_play_buffer; |
| 64 | |
| 65 | /** @brief Collection thread ID */ |
| 66 | static pthread_t uaudio_collect_thread; |
| 67 | |
| 68 | /** @brief Playing thread ID */ |
| 69 | static pthread_t uaudio_play_thread; |
| 70 | |
| 71 | /** @brief Flags */ |
| 72 | static unsigned uaudio_thread_flags; |
| 73 | |
| 74 | static uaudio_callback *uaudio_thread_collect_callback; |
| 75 | static uaudio_playcallback *uaudio_thread_play_callback; |
| 76 | static void *uaudio_thread_userdata; |
| 77 | static int uaudio_thread_started; |
| 78 | static int uaudio_thread_collecting; |
| 79 | static pthread_mutex_t uaudio_thread_lock = PTHREAD_MUTEX_INITIALIZER; |
| 80 | static pthread_cond_t uaudio_thread_cond = PTHREAD_COND_INITIALIZER; |
| 81 | |
| 82 | /** @brief Minimum number of samples per chunk */ |
| 83 | static size_t uaudio_thread_min; |
| 84 | |
| 85 | /** @brief Maximum number of samples per chunk */ |
| 86 | static size_t uaudio_thread_max; |
| 87 | |
| 88 | /** @brief Set when activated, clear when paused */ |
| 89 | static int uaudio_thread_activated; |
| 90 | |
| 91 | /** @brief Return number of buffers currently in use */ |
| 92 | static int uaudio_buffers_used(void) { |
| 93 | return (uaudio_collect_buffer - uaudio_play_buffer) % UAUDIO_THREAD_BUFFERS; |
| 94 | } |
| 95 | |
| 96 | /** @brief Background thread for audio collection |
| 97 | * |
| 98 | * Collects data while activated and communicates its status via @ref |
| 99 | * uaudio_thread_collecting. |
| 100 | */ |
| 101 | static void *uaudio_collect_thread_fn(void attribute((unused)) *arg) { |
| 102 | pthread_mutex_lock(&uaudio_thread_lock); |
| 103 | while(uaudio_thread_started) { |
| 104 | /* Wait until we're activatd */ |
| 105 | if(!uaudio_thread_activated) { |
| 106 | pthread_cond_wait(&uaudio_thread_cond, &uaudio_thread_lock); |
| 107 | continue; |
| 108 | } |
| 109 | /* We are definitely active now */ |
| 110 | uaudio_thread_collecting = 1; |
| 111 | pthread_cond_broadcast(&uaudio_thread_cond); |
| 112 | while(uaudio_thread_activated) { |
| 113 | if(uaudio_buffers_used() < UAUDIO_THREAD_BUFFERS - 1) { |
| 114 | /* At least one buffer is available. We release the lock while |
| 115 | * collecting data so that other already-filled buffers can be played |
| 116 | * without delay. */ |
| 117 | struct uaudio_buffer *const b = &uaudio_buffers[uaudio_collect_buffer]; |
| 118 | pthread_mutex_unlock(&uaudio_thread_lock); |
| 119 | //fprintf(stderr, "C%d.", uaudio_collect_buffer); |
| 120 | |
| 121 | /* Keep on trying until we get the minimum required amount of data */ |
| 122 | b->nsamples = 0; |
| 123 | if(uaudio_thread_activated) { |
| 124 | while(b->nsamples < uaudio_thread_min) { |
| 125 | b->nsamples += uaudio_thread_collect_callback |
| 126 | ((char *)b->samples |
| 127 | + b->nsamples * uaudio_sample_size, |
| 128 | uaudio_thread_max - b->nsamples, |
| 129 | uaudio_thread_userdata); |
| 130 | } |
| 131 | } |
| 132 | pthread_mutex_lock(&uaudio_thread_lock); |
| 133 | /* Advance to next buffer */ |
| 134 | uaudio_collect_buffer = (1 + uaudio_collect_buffer) % UAUDIO_THREAD_BUFFERS; |
| 135 | /* Awaken player */ |
| 136 | pthread_cond_broadcast(&uaudio_thread_cond); |
| 137 | } else |
| 138 | /* No space, wait for player */ |
| 139 | pthread_cond_wait(&uaudio_thread_cond, &uaudio_thread_lock); |
| 140 | } |
| 141 | uaudio_thread_collecting = 0; |
| 142 | pthread_cond_broadcast(&uaudio_thread_cond); |
| 143 | } |
| 144 | pthread_mutex_unlock(&uaudio_thread_lock); |
| 145 | return NULL; |
| 146 | } |
| 147 | |
| 148 | /** @brief Background thread for audio playing |
| 149 | * |
| 150 | * This thread plays data as long as there is something to play. So the |
| 151 | * buffers will drain to empty before deactivation completes. |
| 152 | */ |
| 153 | static void *uaudio_play_thread_fn(void attribute((unused)) *arg) { |
| 154 | int resync = 1; |
| 155 | unsigned last_flags = 0; |
| 156 | unsigned char zero[uaudio_thread_max * uaudio_sample_size]; |
| 157 | memset(zero, 0, sizeof zero); |
| 158 | |
| 159 | while(uaudio_thread_started) { |
| 160 | // If we're paused then just play silence |
| 161 | if(!uaudio_thread_activated) { |
| 162 | pthread_mutex_unlock(&uaudio_thread_lock); |
| 163 | unsigned flags = UAUDIO_PAUSED; |
| 164 | if(last_flags & UAUDIO_PLAYING) |
| 165 | flags |= UAUDIO_PAUSE; |
| 166 | uaudio_thread_play_callback(zero, uaudio_thread_max, |
| 167 | last_flags = flags); |
| 168 | /* We expect the play callback to block for a reasonable period */ |
| 169 | pthread_mutex_lock(&uaudio_thread_lock); |
| 170 | continue; |
| 171 | } |
| 172 | const int used = uaudio_buffers_used(); |
| 173 | int go; |
| 174 | |
| 175 | if(resync) |
| 176 | go = (used == UAUDIO_THREAD_BUFFERS - 1); |
| 177 | else |
| 178 | go = (used > 0); |
| 179 | if(go) { |
| 180 | /* At least one buffer is filled. We release the lock while playing so |
| 181 | * that more collection can go on. */ |
| 182 | struct uaudio_buffer *const b = &uaudio_buffers[uaudio_play_buffer]; |
| 183 | pthread_mutex_unlock(&uaudio_thread_lock); |
| 184 | //fprintf(stderr, "P%d.", uaudio_play_buffer); |
| 185 | size_t played = 0; |
| 186 | while(played < b->nsamples) { |
| 187 | unsigned flags = UAUDIO_PLAYING; |
| 188 | if(last_flags & UAUDIO_PAUSED) |
| 189 | flags |= UAUDIO_RESUME; |
| 190 | played += uaudio_thread_play_callback((char *)b->samples |
| 191 | + played * uaudio_sample_size, |
| 192 | b->nsamples - played, |
| 193 | last_flags = flags); |
| 194 | } |
| 195 | pthread_mutex_lock(&uaudio_thread_lock); |
| 196 | /* Move to next buffer */ |
| 197 | uaudio_play_buffer = (1 + uaudio_play_buffer) % UAUDIO_THREAD_BUFFERS; |
| 198 | /* Awaken collector */ |
| 199 | pthread_cond_broadcast(&uaudio_thread_cond); |
| 200 | resync = 0; |
| 201 | } else { |
| 202 | /* Insufficient data to play, wait for collector */ |
| 203 | pthread_cond_wait(&uaudio_thread_cond, &uaudio_thread_lock); |
| 204 | /* (Still) re-synchronizing */ |
| 205 | resync = 1; |
| 206 | } |
| 207 | } |
| 208 | pthread_mutex_unlock(&uaudio_thread_lock); |
| 209 | return NULL; |
| 210 | } |
| 211 | |
| 212 | /** @brief Create background threads for audio processing |
| 213 | * @param callback Callback to collect audio data |
| 214 | * @param userdata Passed to @p callback |
| 215 | * @param playcallback Callback to play audio data |
| 216 | * @param min Minimum number of samples to play in a chunk |
| 217 | * @param max Maximum number of samples to play in a chunk |
| 218 | * @param flags Flags (not currently used) |
| 219 | * |
| 220 | * @p callback will be called multiple times in quick succession if necessary |
| 221 | * to gather at least @p min samples. Equally @p playcallback may be called |
| 222 | * repeatedly in quick succession to play however much was received in a single |
| 223 | * chunk. |
| 224 | */ |
| 225 | void uaudio_thread_start(uaudio_callback *callback, |
| 226 | void *userdata, |
| 227 | uaudio_playcallback *playcallback, |
| 228 | size_t min, |
| 229 | size_t max, |
| 230 | unsigned flags) { |
| 231 | int e; |
| 232 | uaudio_thread_collect_callback = callback; |
| 233 | uaudio_thread_userdata = userdata; |
| 234 | uaudio_thread_play_callback = playcallback; |
| 235 | uaudio_thread_min = min; |
| 236 | uaudio_thread_max = max; |
| 237 | uaudio_thread_flags = flags; |
| 238 | uaudio_thread_started = 1; |
| 239 | uaudio_thread_activated = 0; |
| 240 | for(int n = 0; n < UAUDIO_THREAD_BUFFERS; ++n) |
| 241 | uaudio_buffers[n].samples = xcalloc_noptr(uaudio_thread_max, |
| 242 | uaudio_sample_size); |
| 243 | uaudio_collect_buffer = uaudio_play_buffer = 0; |
| 244 | if((e = pthread_create(&uaudio_collect_thread, |
| 245 | NULL, |
| 246 | uaudio_collect_thread_fn, |
| 247 | NULL))) |
| 248 | disorder_fatal(e, "pthread_create"); |
| 249 | if((e = pthread_create(&uaudio_play_thread, |
| 250 | NULL, |
| 251 | uaudio_play_thread_fn, |
| 252 | NULL))) |
| 253 | disorder_fatal(e, "pthread_create"); |
| 254 | } |
| 255 | |
| 256 | /** @brief Shut down background threads for audio processing */ |
| 257 | void uaudio_thread_stop(void) { |
| 258 | void *result; |
| 259 | |
| 260 | pthread_mutex_lock(&uaudio_thread_lock); |
| 261 | uaudio_thread_activated = 0; |
| 262 | uaudio_thread_started = 0; |
| 263 | pthread_cond_broadcast(&uaudio_thread_cond); |
| 264 | pthread_mutex_unlock(&uaudio_thread_lock); |
| 265 | pthread_join(uaudio_collect_thread, &result); |
| 266 | pthread_join(uaudio_play_thread, &result); |
| 267 | for(int n = 0; n < UAUDIO_THREAD_BUFFERS; ++n) |
| 268 | xfree(uaudio_buffers[n].samples); |
| 269 | } |
| 270 | |
| 271 | /** @brief Activate audio output */ |
| 272 | void uaudio_thread_activate(void) { |
| 273 | pthread_mutex_lock(&uaudio_thread_lock); |
| 274 | uaudio_thread_activated = 1; |
| 275 | pthread_cond_broadcast(&uaudio_thread_cond); |
| 276 | pthread_mutex_unlock(&uaudio_thread_lock); |
| 277 | } |
| 278 | |
| 279 | /** @brief Deactivate audio output */ |
| 280 | void uaudio_thread_deactivate(void) { |
| 281 | pthread_mutex_lock(&uaudio_thread_lock); |
| 282 | uaudio_thread_activated = 0; |
| 283 | pthread_cond_broadcast(&uaudio_thread_cond); |
| 284 | pthread_mutex_unlock(&uaudio_thread_lock); |
| 285 | } |
| 286 | |
| 287 | /* |
| 288 | Local Variables: |
| 289 | c-basic-offset:2 |
| 290 | comment-column:40 |
| 291 | fill-column:79 |
| 292 | indent-tabs-mode:nil |
| 293 | End: |
| 294 | */ |