alsa: Set period time.
[paraslash.git] / alsa_write.c
1 /*
2 * Copyright (C) 2005-2013 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file alsa_write.c paraslash's alsa output plugin */
8
9 /*
10 * Based in parts on aplay.c from the alsa-utils-1.0.8 package,
11 * Copyright (c) by Jaroslav Kysela <perex@suse.cz>, which is
12 * based on the vplay program by Michael Beck.
13 */
14
15 #include <regex.h>
16 #include <sys/types.h>
17 #include <alsa/asoundlib.h>
18
19 #include "para.h"
20 #include "fd.h"
21 #include "string.h"
22 #include "list.h"
23 #include "sched.h"
24 #include "ggo.h"
25 #include "buffer_tree.h"
26 #include "write.h"
27 #include "write_common.h"
28 #include "alsa_write.cmdline.h"
29 #include "error.h"
30
31 /** Data specific to the alsa writer. */
32 struct private_alsa_write_data {
33 /** The alsa handle */
34 snd_pcm_t *handle;
35 /** Determined and set by alsa_init(). */
36 int bytes_per_frame;
37 /*
38 * If the sample rate is not given at the command line and no wav
39 * header was detected, the btr exec mechanism is employed to query the
40 * ancestor buffer tree nodes for this information. In a typical setup
41 * the decoder passes the sample rate back to the alsa writer.
42 *
43 * \sa \ref btr_exec_up().
44 */
45 unsigned sample_rate;
46 /*
47 * The sample format (8/16 bit, signed/unsigned, little/big endian) is
48 * determined in the same way as the \a sample_rate.
49 */
50 snd_pcm_format_t sample_format;
51 /* The number of channels, again determined like \a sample_rate. */
52 unsigned channels;
53 struct timeval drain_barrier;
54 /* File descriptor for select(). */
55 int poll_fd;
56 };
57
58 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
59 {
60 switch (sf) {
61 case SF_S8: return SND_PCM_FORMAT_S8;
62 case SF_U8: return SND_PCM_FORMAT_U8;
63 case SF_S16_LE: return SND_PCM_FORMAT_S16_LE;
64 case SF_S16_BE: return SND_PCM_FORMAT_S16_BE;
65 case SF_U16_LE: return SND_PCM_FORMAT_U16_LE;
66 case SF_U16_BE: return SND_PCM_FORMAT_U16_BE;
67 default: return SND_PCM_FORMAT_S16_LE;
68 }
69 }
70
71 /* Install PCM software and hardware configuration. */
72 static int alsa_init(struct private_alsa_write_data *pad,
73 struct alsa_write_args_info *conf)
74 {
75 snd_pcm_hw_params_t *hwparams;
76 snd_pcm_sw_params_t *swparams;
77 snd_pcm_uframes_t start_threshold, stop_threshold;
78 snd_pcm_uframes_t buffer_size, period_size;
79 snd_output_t *output_log;
80 unsigned buffer_time;
81 int ret;
82 const char *msg;
83 unsigned period_time;
84
85 PARA_INFO_LOG("opening %s\n", conf->device_arg);
86 msg = "unable to open pcm";
87 ret = snd_pcm_open(&pad->handle, conf->device_arg,
88 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
89 if (ret < 0)
90 goto fail;
91 snd_pcm_hw_params_alloca(&hwparams);
92 msg = "Broken alsa configuration";
93 ret = snd_pcm_hw_params_any(pad->handle, hwparams);
94 if (ret < 0)
95 goto fail;
96 msg = "access type not available";
97 ret = snd_pcm_hw_params_set_access(pad->handle, hwparams,
98 SND_PCM_ACCESS_RW_INTERLEAVED);
99 if (ret < 0)
100 goto fail;
101 msg = "sample format not available";
102 ret = snd_pcm_hw_params_set_format(pad->handle, hwparams,
103 pad->sample_format);
104 if (ret < 0)
105 goto fail;
106 msg = "channels count not available";
107 ret = snd_pcm_hw_params_set_channels(pad->handle, hwparams,
108 pad->channels);
109 if (ret < 0)
110 goto fail;
111 msg = "could not set sample rate";
112 ret = snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
113 &pad->sample_rate, NULL);
114 if (ret < 0)
115 goto fail;
116 msg = "unable to get buffer time";
117 ret = snd_pcm_hw_params_get_buffer_time_max(hwparams, &buffer_time,
118 NULL);
119 if (ret < 0 || buffer_time == 0)
120 goto fail;
121 /* buffer at most 500 milliseconds */
122 buffer_time = PARA_MIN(buffer_time, 500U * 1000U);
123 msg = "could not set buffer time";
124 ret = snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
125 &buffer_time, NULL);
126 if (ret < 0)
127 goto fail;
128 period_time = buffer_time / 4;
129 msg = "could not set period time";
130 ret = snd_pcm_hw_params_set_period_time_near(pad->handle, hwparams,
131 &period_time, 0);
132 if (ret < 0)
133 goto fail;
134
135 msg = "unable to install hw params";
136 ret = snd_pcm_hw_params(pad->handle, hwparams);
137 if (ret < 0)
138 goto fail;
139 snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
140 snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
141 msg = "period size equals buffer size";
142 if (period_size == buffer_size)
143 goto fail;
144
145 /* software parameter setup */
146 snd_pcm_sw_params_alloca(&swparams);
147 snd_pcm_sw_params_current(pad->handle, swparams);
148 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
149 if (buffer_size < 1)
150 start_threshold = 1;
151 else
152 start_threshold = PARA_MIN(buffer_size,
153 (snd_pcm_uframes_t)pad->sample_rate);
154 msg = "could not set start threshold";
155 ret = snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
156 start_threshold);
157 if (ret < 0)
158 goto fail;
159 stop_threshold = buffer_size;
160 msg = "could not set stop threshold";
161 ret = snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
162 stop_threshold);
163 if (ret < 0)
164 goto fail;
165 msg = "unable to install sw params";
166 ret = snd_pcm_sw_params(pad->handle, swparams);
167 if (ret < 0)
168 goto fail;
169 msg = "unable to determine bytes per frame";
170 ret = snd_pcm_format_physical_width(pad->sample_format);
171 if (ret <= 0)
172 goto fail;
173 pad->bytes_per_frame = ret * pad->channels / 8;
174 msg = "failed to set alsa handle to nonblock mode";
175 ret = snd_pcm_nonblock(pad->handle, 1);
176 if (ret < 0)
177 goto fail;
178 ret = snd_output_buffer_open(&output_log);
179 if (ret == 0) {
180 char *buf, *p;
181 size_t sz;
182 PARA_DEBUG_LOG("dumping alsa configuration\n");
183 snd_pcm_dump(pad->handle, output_log);
184 snd_pcm_hw_params_dump(hwparams, output_log);
185 sz = snd_output_buffer_string(output_log, &buf);
186 for (p = buf; p < buf + sz;) {
187 char *q = memchr(p, '\n', buf + sz - p);
188 if (!q)
189 break;
190 *q = '\0';
191 PARA_DEBUG_LOG("%s\n", p);
192 p = q + 1;
193 }
194 snd_output_close(output_log);
195 }
196 return 1;
197 fail:
198 if (ret < 0)
199 PARA_ERROR_LOG("%s: %s\n", msg, snd_strerror(-ret));
200 else
201 PARA_ERROR_LOG("%s\n", msg);
202 return -E_ALSA;
203 }
204
205 static void alsa_write_pre_select(struct sched *s, struct task *t)
206 {
207 struct pollfd pfd;
208 struct writer_node *wn = container_of(t, struct writer_node, task);
209 struct private_alsa_write_data *pad = wn->private_data;
210 int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
211
212 if (pad)
213 pad->poll_fd = -1;
214 if (ret == 0)
215 return;
216 if (!pad) {
217 sched_min_delay(s);
218 return;
219 }
220 if (ret < 0) {
221 sched_request_barrier_or_min_delay(&pad->drain_barrier, s);
222 return;
223 }
224 ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1);
225 if (ret < 0) {
226 PARA_ERROR_LOG("could not get alsa poll fd: %s\n",
227 snd_strerror(-ret));
228 return;
229 }
230 pad->poll_fd = pfd.fd;
231 para_fd_set(pfd.fd, &s->rfds, &s->max_fileno);
232 }
233
234 static void alsa_close(struct writer_node *wn)
235 {
236 struct private_alsa_write_data *pad = wn->private_data;
237 PARA_INFO_LOG("closing writer node %p\n", wn);
238
239 if (!pad)
240 return;
241 /*
242 * It's OK to have a blocking operation here because we already made
243 * sure that the PCM output buffer is (nearly) empty.
244 */
245 snd_pcm_nonblock(pad->handle, 0);
246 snd_pcm_drain(pad->handle);
247 snd_pcm_close(pad->handle);
248 snd_config_update_free_global();
249 free(pad);
250 }
251
252 static int alsa_write_post_select(__a_unused struct sched *s,
253 struct task *t)
254 {
255 struct writer_node *wn = container_of(t, struct writer_node, task);
256 struct private_alsa_write_data *pad = wn->private_data;
257 struct btr_node *btrn = wn->btrn;
258 char *data;
259 size_t bytes;
260 snd_pcm_sframes_t frames;
261 int ret;
262
263 ret = task_get_notification(t);
264 if (ret < 0)
265 goto err;
266 again:
267 ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
268 if (ret == 0)
269 return 0;
270 btr_merge(btrn, wn->min_iqs);
271 bytes = btr_next_buffer(btrn, &data);
272 if (ret < 0 || bytes < wn->min_iqs) { /* eof */
273 assert(btr_no_parent(btrn));
274 ret = -E_WRITE_COMMON_EOF;
275 if (!pad)
276 goto err;
277 /* wait until pending frames are played */
278 if (pad->drain_barrier.tv_sec == 0) {
279 PARA_DEBUG_LOG("waiting for device to drain\n");
280 tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
281 &pad->drain_barrier);
282 return 0;
283 }
284 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
285 goto err;
286 return 0;
287 }
288 if (!pad) {
289 int32_t val;
290
291 if (bytes == 0) /* no data available */
292 return 0;
293 pad = para_calloc(sizeof(*pad));
294 get_btr_sample_rate(btrn, &val);
295 pad->sample_rate = val;
296 get_btr_channels(btrn, &val);
297 pad->channels = val;
298 get_btr_sample_format(btrn, &val);
299 pad->sample_format = get_alsa_pcm_format(val);
300
301 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
302 pad->sample_rate);
303 ret = alsa_init(pad, wn->conf);
304 if (ret < 0) {
305 free(pad);
306 goto err;
307 }
308 wn->private_data = pad;
309 wn->min_iqs = pad->bytes_per_frame;
310 goto again;
311 }
312 if (pad->poll_fd < 0 || !FD_ISSET(pad->poll_fd, &s->rfds))
313 return 0;
314 frames = bytes / pad->bytes_per_frame;
315 frames = snd_pcm_writei(pad->handle, data, frames);
316 if (frames == 0 || frames == -EAGAIN) {
317 /*
318 * The alsa poll fd was ready for IO but we failed to write to
319 * the alsa handle. This means another event is pending. We
320 * don't care about that but we have to dispatch the event in
321 * order to avoid a busy loop. So we simply read from the poll
322 * fd.
323 */
324 char buf[100];
325 if (read(pad->poll_fd, buf, 100))
326 do_nothing;
327 return 0;
328 }
329 if (frames > 0) {
330 btr_consume(btrn, frames * pad->bytes_per_frame);
331 goto again;
332 }
333 if (frames == -EPIPE) {
334 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
335 snd_pcm_prepare(pad->handle);
336 return 0;
337 }
338 PARA_ERROR_LOG("alsa write error: %s\n", snd_strerror(-frames));
339 ret = -E_ALSA;
340 err:
341 assert(ret < 0);
342 btr_remove_node(&wn->btrn);
343 return ret;
344 }
345
346 __malloc static void *alsa_parse_config_or_die(int argc, char **argv)
347 {
348 struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
349
350 /* exits on errors */
351 alsa_write_cmdline_parser(argc, argv, conf);
352 return conf;
353 }
354
355 static void alsa_free_config(void *conf)
356 {
357 alsa_write_cmdline_parser_free(conf);
358 }
359
360 /**
361 * The init function of the alsa writer.
362 *
363 * \param w Pointer to the writer to initialize.
364 *
365 * \sa struct \ref writer.
366 */
367 void alsa_write_init(struct writer *w)
368 {
369 struct alsa_write_args_info dummy;
370
371 alsa_write_cmdline_parser_init(&dummy);
372 w->close = alsa_close;
373 w->pre_select = alsa_write_pre_select;
374 w->post_select = alsa_write_post_select;
375 w->parse_config_or_die = alsa_parse_config_or_die;
376 w->free_config = alsa_free_config;
377 w->help = (struct ggo_help)DEFINE_GGO_HELP(alsa_write);
378 alsa_write_cmdline_parser_free(&dummy);
379 }