write: Make get_btr_value() return void.
[paraslash.git] / alsa_write.c
1 /*
2 * Copyright (C) 2005-2010 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 <dirent.h>
18 #include <alsa/asoundlib.h>
19 #include <sys/time.h>
20 #include <stdbool.h>
21
22 #include "para.h"
23 #include "fd.h"
24 #include "string.h"
25 #include "list.h"
26 #include "sched.h"
27 #include "ggo.h"
28 #include "buffer_tree.h"
29 #include "write.h"
30 #include "write_common.h"
31 #include "alsa_write.cmdline.h"
32 #include "error.h"
33
34 /** always use 16 bit little endian */
35 #define FORMAT SND_PCM_FORMAT_S16_LE
36
37 /** Data specific to the alsa writer. */
38 struct private_alsa_write_data {
39 /** The alsa handle */
40 snd_pcm_t *handle;
41 /** Determined and set by alsa_open(). */
42 int bytes_per_frame;
43 /** The approximate maximum buffer duration in us. */
44 unsigned buffer_time;
45 /* Number of frames that fit into the buffer. */
46 snd_pcm_uframes_t buffer_frames;
47 /**
48 * The sample rate given by command line option or the decoder
49 * of the writer node group.
50 */
51 unsigned sample_rate;
52 /**
53 * The number of channels, given by command line option or the
54 * decoder of the writer node group.
55 */
56 unsigned channels;
57 struct timeval drain_barrier;
58 };
59
60 /* Install PCM software and hardware configuration. */
61 static int alsa_init(struct private_alsa_write_data *pad,
62 struct alsa_write_args_info *conf)
63 {
64 snd_pcm_hw_params_t *hwparams;
65 snd_pcm_sw_params_t *swparams;
66 snd_pcm_uframes_t start_threshold, stop_threshold;
67 snd_pcm_uframes_t period_size;
68 int err;
69
70 PARA_INFO_LOG("opening %s\n", conf->device_arg);
71 err = snd_pcm_open(&pad->handle, conf->device_arg,
72 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
73 if (err < 0)
74 return -E_PCM_OPEN;
75
76 snd_pcm_hw_params_alloca(&hwparams);
77 snd_pcm_sw_params_alloca(&swparams);
78 if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
79 return -E_BROKEN_CONF;
80 if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
81 SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
82 return -E_ACCESS_TYPE;
83 if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
84 return -E_SAMPLE_FORMAT;
85 if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
86 pad->channels) < 0)
87 return -E_CHANNEL_COUNT;
88 if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
89 &pad->sample_rate, NULL) < 0)
90 return -E_SET_RATE;
91 err = snd_pcm_hw_params_get_buffer_time_max(hwparams,
92 &pad->buffer_time, NULL);
93 if (err < 0 || !pad->buffer_time)
94 return -E_GET_BUFFER_TIME;
95 PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
96 if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
97 &pad->buffer_time, NULL) < 0)
98 return -E_SET_BUFFER_TIME;
99 if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
100 return -E_HW_PARAMS;
101 snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
102 snd_pcm_hw_params_get_buffer_size(hwparams, &pad->buffer_frames);
103 PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad->buffer_frames,
104 period_size);
105 if (period_size == pad->buffer_frames)
106 return -E_BAD_PERIOD;
107 snd_pcm_sw_params_current(pad->handle, swparams);
108 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
109 if (pad->buffer_frames < 1)
110 start_threshold = 1;
111 else
112 start_threshold = PARA_MIN(pad->buffer_frames,
113 (snd_pcm_uframes_t)pad->sample_rate);
114 if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
115 start_threshold) < 0)
116 return -E_START_THRESHOLD;
117 stop_threshold = pad->buffer_frames;
118 if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
119 stop_threshold) < 0)
120 return -E_STOP_THRESHOLD;
121 if (snd_pcm_sw_params(pad->handle, swparams) < 0)
122 PARA_WARNING_LOG("unable to install sw params\n");
123 pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
124 * pad->channels / 8;
125 if (pad->bytes_per_frame <= 0)
126 return -E_PHYSICAL_WIDTH;
127 PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
128 if (snd_pcm_nonblock(pad->handle, 1))
129 PARA_ERROR_LOG("failed to set nonblock mode\n");
130 return 1;
131 }
132
133 /* Open an instance of the alsa writer. */
134 static int alsa_open(struct writer_node *wn)
135 {
136 wn->private_data = para_calloc(sizeof(struct private_alsa_write_data));
137 return 1;
138 }
139
140 static void alsa_write_pre_select(struct sched *s, struct task *t)
141 {
142 struct writer_node *wn = container_of(t, struct writer_node, task);
143 struct private_alsa_write_data *pad = wn->private_data;
144 struct timeval tv;
145 snd_pcm_sframes_t avail, underrun;
146 int ret;
147
148 if (!pad->handle)
149 return;
150 ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
151 if (ret < 0)
152 sched_request_timeout_ms(20, s);
153 if (ret <= 0)
154 return;
155 /*
156 * Data is available to be written to the alsa handle. Compute number
157 * of milliseconds until next buffer underrun would occur.
158 *
159 * snd_pcm_avail_update() updates the current available count of
160 * samples for writing. It is a light method to obtain current stream
161 * position, because it does not require the user <-> kernel context
162 * switch, but the value is less accurate, because ring buffer pointers
163 * are updated in kernel drivers only when an interrupt occurs.
164 */
165 avail = snd_pcm_avail_update(pad->handle);
166 if (avail < 0)
167 avail = 0;
168 underrun = (pad->buffer_frames - avail) * pad->buffer_time
169 / pad->buffer_frames / 1000;
170 if (underrun < 50)
171 underrun = 50;
172 underrun -= 50;
173 ms2tv(underrun, &tv);
174 if (tv_diff(&s->timeout, &tv, NULL) > 0)
175 s->timeout = tv;
176 }
177
178 static void alsa_close(struct writer_node *wn)
179 {
180 struct private_alsa_write_data *pad = wn->private_data;
181 PARA_INFO_LOG("closing writer node %p\n", wn);
182
183 if (pad->handle) {
184 /*
185 * It's OK to have a blocking operation here because we already
186 * made sure that the PCM output buffer is (nearly) empty.
187 */
188 snd_pcm_nonblock(pad->handle, 0);
189 snd_pcm_drain(pad->handle);
190 snd_pcm_close(pad->handle);
191 snd_config_update_free_global();
192 }
193 free(pad);
194 }
195
196 static void alsa_write_post_select(__a_unused struct sched *s,
197 struct task *t)
198 {
199 struct writer_node *wn = container_of(t, struct writer_node, task);
200 struct private_alsa_write_data *pad = wn->private_data;
201 struct btr_node *btrn = wn->btrn;
202 char *data;
203 size_t bytes;
204 snd_pcm_sframes_t frames;
205 int ret;
206
207 again:
208 t->error = 0;
209 ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
210 if (ret == 0)
211 return;
212 btr_merge(btrn, wn->min_iqs);
213 bytes = btr_next_buffer(btrn, &data);
214 if (ret < 0 || bytes < pad->bytes_per_frame) { /* eof */
215 assert(btr_no_parent(btrn));
216 ret = -E_ALSA_EOF;
217 if (!pad->handle)
218 goto err;
219 /* wait until pending frames are played */
220 if (pad->drain_barrier.tv_sec == 0) {
221 PARA_DEBUG_LOG("waiting for device to drain\n");
222 tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
223 &pad->drain_barrier);
224 return;
225 }
226 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
227 goto err;
228 return;
229 }
230 if (!pad->handle) {
231 int32_t val;
232 if (bytes == 0) /* no data available */
233 return;
234 get_btr_sample_rate(btrn, &val);
235 pad->sample_rate = val;
236 get_btr_channels(btrn, &val);
237 pad->channels = val;
238 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
239 pad->sample_rate);
240 ret = alsa_init(pad, wn->conf);
241 if (ret < 0)
242 goto err;
243 wn->min_iqs = pad->bytes_per_frame;
244 }
245 frames = bytes / pad->bytes_per_frame;
246 frames = snd_pcm_writei(pad->handle, data, frames);
247 if (frames >= 0) {
248 btr_consume(btrn, frames * pad->bytes_per_frame);
249 goto again;
250 }
251 if (frames == -EPIPE) {
252 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
253 snd_pcm_prepare(pad->handle);
254 return;
255 }
256 if (frames == -EAGAIN)
257 return;
258 PARA_WARNING_LOG("%s\n", snd_strerror(-frames));
259 ret = -E_ALSA_WRITE;
260 err:
261 assert(ret < 0);
262 btr_remove_node(btrn);
263 t->error = ret;
264 }
265
266 __malloc static void *alsa_parse_config(const char *options)
267 {
268 int ret;
269 struct alsa_write_args_info *conf
270 = para_calloc(sizeof(struct alsa_write_args_info));
271
272 PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
273 ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
274 if (ret)
275 goto err_out;
276 PARA_INFO_LOG("help given: %d\n", conf->help_given);
277 return conf;
278 err_out:
279 free(conf);
280 return NULL;
281 }
282
283 static void alsa_free_config(void *conf)
284 {
285 alsa_cmdline_parser_free(conf);
286 }
287
288 /**
289 * The init function of the alsa writer.
290 *
291 * \param w Pointer to the writer to initialize.
292 *
293 * \sa struct \ref writer.
294 */
295 void alsa_write_init(struct writer *w)
296 {
297 struct alsa_write_args_info dummy;
298
299 alsa_cmdline_parser_init(&dummy);
300 w->open = alsa_open;
301 w->close = alsa_close;
302 w->pre_select = alsa_write_pre_select;
303 w->post_select = alsa_write_post_select;
304 w->parse_config = alsa_parse_config;
305 w->shutdown = NULL; /* nothing to do */
306 w->free_config = alsa_free_config;
307 w->help = (struct ggo_help) {
308 .short_help = alsa_write_args_info_help,
309 .detailed_help = alsa_write_args_info_detailed_help
310 };
311 alsa_cmdline_parser_free(&dummy);
312 }