alsa: Work around poll fd problems.
[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 /* time until buffer underrun occurs, in microseconds */
54 unsigned buffer_time;
55 struct timeval drain_barrier;
56 /* File descriptor for select(). */
57 int poll_fd;
58 };
59
60 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
61 {
62 switch (sf) {
63 case SF_S8: return SND_PCM_FORMAT_S8;
64 case SF_U8: return SND_PCM_FORMAT_U8;
65 case SF_S16_LE: return SND_PCM_FORMAT_S16_LE;
66 case SF_S16_BE: return SND_PCM_FORMAT_S16_BE;
67 case SF_U16_LE: return SND_PCM_FORMAT_U16_LE;
68 case SF_U16_BE: return SND_PCM_FORMAT_U16_BE;
69 default: return SND_PCM_FORMAT_S16_LE;
70 }
71 }
72
73 /* Install PCM software and hardware configuration. */
74 static int alsa_init(struct private_alsa_write_data *pad,
75 struct alsa_write_args_info *conf)
76 {
77 snd_pcm_hw_params_t *hwparams;
78 snd_pcm_sw_params_t *swparams;
79 snd_pcm_uframes_t start_threshold, stop_threshold;
80 snd_pcm_uframes_t buffer_size, period_size;
81 snd_output_t *output_log;
82 int ret;
83 const char *msg;
84 unsigned period_time;
85
86 PARA_INFO_LOG("opening %s\n", conf->device_arg);
87 msg = "unable to open pcm";
88 ret = snd_pcm_open(&pad->handle, conf->device_arg,
89 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
90 if (ret < 0)
91 goto fail;
92 snd_pcm_hw_params_alloca(&hwparams);
93 msg = "Broken alsa configuration";
94 ret = snd_pcm_hw_params_any(pad->handle, hwparams);
95 if (ret < 0)
96 goto fail;
97 msg = "access type not available";
98 ret = snd_pcm_hw_params_set_access(pad->handle, hwparams,
99 SND_PCM_ACCESS_RW_INTERLEAVED);
100 if (ret < 0)
101 goto fail;
102 msg = "sample format not available";
103 ret = snd_pcm_hw_params_set_format(pad->handle, hwparams,
104 pad->sample_format);
105 if (ret < 0)
106 goto fail;
107 msg = "channels count not available";
108 ret = snd_pcm_hw_params_set_channels(pad->handle, hwparams,
109 pad->channels);
110 if (ret < 0)
111 goto fail;
112 msg = "could not set sample rate";
113 ret = snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
114 &pad->sample_rate, NULL);
115 if (ret < 0)
116 goto fail;
117 msg = "unable to get buffer time";
118 ret = snd_pcm_hw_params_get_buffer_time_max(hwparams, &pad->buffer_time,
119 NULL);
120 if (ret < 0 || pad->buffer_time == 0)
121 goto fail;
122 /* buffer at most 500 milliseconds */
123 pad->buffer_time = PARA_MIN(pad->buffer_time, 500U * 1000U);
124 msg = "could not set buffer time";
125 ret = snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
126 &pad->buffer_time, NULL);
127 if (ret < 0)
128 goto fail;
129 period_time = pad->buffer_time / 4;
130 msg = "could not set period time";
131 ret = snd_pcm_hw_params_set_period_time_near(pad->handle, hwparams,
132 &period_time, 0);
133 if (ret < 0)
134 goto fail;
135
136 msg = "unable to install hw params";
137 ret = snd_pcm_hw_params(pad->handle, hwparams);
138 if (ret < 0)
139 goto fail;
140 snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
141 snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
142 msg = "period size equals buffer size";
143 if (period_size == buffer_size)
144 goto fail;
145
146 /* software parameter setup */
147 snd_pcm_sw_params_alloca(&swparams);
148 snd_pcm_sw_params_current(pad->handle, swparams);
149 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
150 if (buffer_size < 1)
151 start_threshold = 1;
152 else
153 start_threshold = PARA_MIN(buffer_size,
154 (snd_pcm_uframes_t)pad->sample_rate);
155 msg = "could not set start threshold";
156 ret = snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
157 start_threshold);
158 if (ret < 0)
159 goto fail;
160 stop_threshold = buffer_size;
161 msg = "could not set stop threshold";
162 ret = snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
163 stop_threshold);
164 if (ret < 0)
165 goto fail;
166 msg = "unable to install sw params";
167 ret = snd_pcm_sw_params(pad->handle, swparams);
168 if (ret < 0)
169 goto fail;
170 msg = "unable to determine bytes per frame";
171 ret = snd_pcm_format_physical_width(pad->sample_format);
172 if (ret <= 0)
173 goto fail;
174 pad->bytes_per_frame = ret * pad->channels / 8;
175 msg = "failed to set alsa handle to nonblock mode";
176 ret = snd_pcm_nonblock(pad->handle, 1);
177 if (ret < 0)
178 goto fail;
179 ret = snd_output_buffer_open(&output_log);
180 if (ret == 0) {
181 char *buf, *p;
182 size_t sz;
183 PARA_DEBUG_LOG("dumping alsa configuration\n");
184 snd_pcm_dump(pad->handle, output_log);
185 snd_pcm_hw_params_dump(hwparams, output_log);
186 sz = snd_output_buffer_string(output_log, &buf);
187 for (p = buf; p < buf + sz;) {
188 char *q = memchr(p, '\n', buf + sz - p);
189 if (!q)
190 break;
191 *q = '\0';
192 PARA_DEBUG_LOG("%s\n", p);
193 p = q + 1;
194 }
195 snd_output_close(output_log);
196 }
197 return 1;
198 fail:
199 if (ret < 0)
200 PARA_ERROR_LOG("%s: %s\n", msg, snd_strerror(-ret));
201 else
202 PARA_ERROR_LOG("%s\n", msg);
203 return -E_ALSA;
204 }
205
206 static void alsa_write_pre_select(struct sched *s, struct task *t)
207 {
208 struct pollfd pfd;
209 struct writer_node *wn = container_of(t, struct writer_node, task);
210 struct private_alsa_write_data *pad = wn->private_data;
211 int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
212
213 if (pad)
214 pad->poll_fd = -1;
215 if (ret == 0)
216 return;
217 if (!pad) {
218 sched_min_delay(s);
219 return;
220 }
221 if (ret < 0) {
222 sched_request_barrier_or_min_delay(&pad->drain_barrier, s);
223 return;
224 }
225 /* wait at most 50% of the buffer time */
226 sched_request_timeout_ms(pad->buffer_time / 2 / 1000, s);
227 ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1);
228 if (ret < 0) {
229 PARA_ERROR_LOG("could not get alsa poll fd: %s\n",
230 snd_strerror(-ret));
231 return;
232 }
233 pad->poll_fd = pfd.fd;
234 para_fd_set(pfd.fd, &s->rfds, &s->max_fileno);
235 }
236
237 static void alsa_close(struct writer_node *wn)
238 {
239 struct private_alsa_write_data *pad = wn->private_data;
240 PARA_INFO_LOG("closing writer node %p\n", wn);
241
242 if (!pad)
243 return;
244 /*
245 * It's OK to have a blocking operation here because we already made
246 * sure that the PCM output buffer is (nearly) empty.
247 */
248 snd_pcm_nonblock(pad->handle, 0);
249 snd_pcm_drain(pad->handle);
250 snd_pcm_close(pad->handle);
251 snd_config_update_free_global();
252 free(pad);
253 }
254
255 static int alsa_write_post_select(__a_unused struct sched *s,
256 struct task *t)
257 {
258 struct writer_node *wn = container_of(t, struct writer_node, task);
259 struct private_alsa_write_data *pad = wn->private_data;
260 struct btr_node *btrn = wn->btrn;
261 char *data;
262 size_t bytes;
263 snd_pcm_sframes_t frames;
264 int ret;
265
266 ret = task_get_notification(t);
267 if (ret < 0)
268 goto err;
269 again:
270 ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
271 if (ret == 0)
272 return 0;
273 btr_merge(btrn, wn->min_iqs);
274 bytes = btr_next_buffer(btrn, &data);
275 if (ret < 0 || bytes < wn->min_iqs) { /* eof */
276 assert(btr_no_parent(btrn));
277 ret = -E_WRITE_COMMON_EOF;
278 if (!pad)
279 goto err;
280 /* wait until pending frames are played */
281 if (pad->drain_barrier.tv_sec == 0) {
282 PARA_DEBUG_LOG("waiting for device to drain\n");
283 tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
284 &pad->drain_barrier);
285 return 0;
286 }
287 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
288 goto err;
289 return 0;
290 }
291 if (!pad) {
292 int32_t val;
293
294 if (bytes == 0) /* no data available */
295 return 0;
296 pad = para_calloc(sizeof(*pad));
297 get_btr_sample_rate(btrn, &val);
298 pad->sample_rate = val;
299 get_btr_channels(btrn, &val);
300 pad->channels = val;
301 get_btr_sample_format(btrn, &val);
302 pad->sample_format = get_alsa_pcm_format(val);
303
304 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
305 pad->sample_rate);
306 ret = alsa_init(pad, wn->conf);
307 if (ret < 0) {
308 free(pad);
309 goto err;
310 }
311 wn->private_data = pad;
312 wn->min_iqs = pad->bytes_per_frame;
313 goto again;
314 }
315 frames = bytes / pad->bytes_per_frame;
316 frames = snd_pcm_writei(pad->handle, data, frames);
317 if (frames == 0 || frames == -EAGAIN) {
318 char buf[100];
319 if (pad->poll_fd >= 0 && FD_ISSET(pad->poll_fd, &s->rfds))
320 if (read(pad->poll_fd, buf, 100))
321 do_nothing;
322 return 0;
323 }
324 if (frames > 0) {
325 btr_consume(btrn, frames * pad->bytes_per_frame);
326 goto again;
327 }
328 if (frames == -EPIPE) {
329 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
330 snd_pcm_prepare(pad->handle);
331 return 0;
332 }
333 PARA_ERROR_LOG("alsa write error: %s\n", snd_strerror(-frames));
334 ret = -E_ALSA;
335 err:
336 assert(ret < 0);
337 btr_remove_node(&wn->btrn);
338 return ret;
339 }
340
341 __malloc static void *alsa_parse_config_or_die(int argc, char **argv)
342 {
343 struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
344
345 /* exits on errors */
346 alsa_write_cmdline_parser(argc, argv, conf);
347 return conf;
348 }
349
350 static void alsa_free_config(void *conf)
351 {
352 alsa_write_cmdline_parser_free(conf);
353 }
354
355 /**
356 * The init function of the alsa writer.
357 *
358 * \param w Pointer to the writer to initialize.
359 *
360 * \sa struct \ref writer.
361 */
362 void alsa_write_init(struct writer *w)
363 {
364 struct alsa_write_args_info dummy;
365
366 alsa_write_cmdline_parser_init(&dummy);
367 w->close = alsa_close;
368 w->pre_select = alsa_write_pre_select;
369 w->post_select = alsa_write_post_select;
370 w->parse_config_or_die = alsa_parse_config_or_die;
371 w->free_config = alsa_free_config;
372 w->help = (struct ggo_help)DEFINE_GGO_HELP(alsa_write);
373 alsa_write_cmdline_parser_free(&dummy);
374 }