alsa_write: Print duration of buffer undderuns.
[paraslash.git] / alsa_write.c
1 /*
2 * Copyright (C) 2005-2009 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
21 #include "para.h"
22 #include "fd.h"
23 #include "string.h"
24 #include "list.h"
25 #include "sched.h"
26 #include "ggo.h"
27 #include "write.h"
28 #include "alsa_write.cmdline.h"
29 #include "error.h"
30
31 /** always use 16 bit little endian */
32 #define FORMAT SND_PCM_FORMAT_S16_LE
33
34 /** Data specific to the alsa writer. */
35 struct private_alsa_write_data {
36 /** The alsa handle */
37 snd_pcm_t *handle;
38 /** Determined and set by alsa_open(). */
39 int bytes_per_frame;
40 /** The approximate maximum buffer duration in us. */
41 unsigned buffer_time;
42 /* Number of frames that fit into the buffer. */
43 unsigned buffer_frames;
44 /**
45 * The samplerate given by command line option or the decoder
46 * of the writer node group.
47 */
48 unsigned samplerate;
49 /**
50 * The number of channels, given by command line option or the
51 * decoder of the writer node group.
52 */
53 unsigned channels;
54 };
55
56 /* Install PCM software and hardware configuration. */
57 static int alsa_init(struct private_alsa_write_data *pad,
58 struct alsa_write_args_info *conf)
59 {
60 snd_pcm_hw_params_t *hwparams;
61 snd_pcm_sw_params_t *swparams;
62 snd_pcm_uframes_t buffer_size, start_threshold, stop_threshold;
63 snd_pcm_uframes_t period_size;
64 int err;
65
66 err = snd_pcm_open(&pad->handle, conf->device_arg,
67 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
68 if (err < 0)
69 return -E_PCM_OPEN;
70
71 snd_pcm_hw_params_alloca(&hwparams);
72 snd_pcm_sw_params_alloca(&swparams);
73 if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
74 return -E_BROKEN_CONF;
75 if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
76 SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
77 return -E_ACCESS_TYPE;
78 if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
79 return -E_SAMPLE_FORMAT;
80 if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
81 pad->channels) < 0)
82 return -E_CHANNEL_COUNT;
83 if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
84 &pad->samplerate, NULL) < 0)
85 return -E_SET_RATE;
86 err = snd_pcm_hw_params_get_buffer_time_max(hwparams,
87 &pad->buffer_time, NULL);
88 if (err < 0 || !pad->buffer_time)
89 return -E_GET_BUFFER_TIME;
90 PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
91 if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
92 &pad->buffer_time, NULL) < 0)
93 return -E_SET_BUFFER_TIME;
94 if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
95 return -E_HW_PARAMS;
96 snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
97 snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
98 PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", buffer_size,
99 period_size);
100 if (period_size == buffer_size)
101 return -E_BAD_PERIOD;
102 snd_pcm_sw_params_current(pad->handle, swparams);
103 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
104 if (buffer_size < 1)
105 start_threshold = 1;
106 else
107 start_threshold = PARA_MIN(buffer_size,
108 (snd_pcm_uframes_t)pad->samplerate);
109 if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
110 start_threshold) < 0)
111 return -E_START_THRESHOLD;
112 stop_threshold = buffer_size;
113 if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
114 stop_threshold) < 0)
115 return -E_STOP_THRESHOLD;
116 if (snd_pcm_sw_params(pad->handle, swparams) < 0)
117 PARA_WARNING_LOG("unable to install sw params\n");
118 pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
119 * pad->channels / 8;
120 if (pad->bytes_per_frame <= 0)
121 return -E_PHYSICAL_WIDTH;
122 PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
123 if (snd_pcm_nonblock(pad->handle, 1))
124 PARA_ERROR_LOG("failed to set nonblock mode\n");
125 pad->buffer_frames = 1000 * pad->buffer_time / pad->samplerate;
126 PARA_INFO_LOG("max buffered frames: %d\n", pad->buffer_frames);
127 return 1;
128 }
129
130 /* Open an instance of the alsa writer. */
131 static int alsa_open(struct writer_node *wn)
132 {
133 struct alsa_write_args_info *conf = wn->conf;
134 struct writer_node_group *wng = wn->wng;
135 struct private_alsa_write_data *pad = para_calloc(sizeof(*pad));
136
137 wn->private_data = pad;
138 if (!conf->samplerate_given && wng->samplerate)
139 pad->samplerate = *wng->samplerate;
140 else
141 pad->samplerate = conf->samplerate_arg;
142 if (!conf->channels_given && wng->channels)
143 pad->channels = *wng->channels;
144 else
145 pad->channels = conf->channels_arg;
146 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
147 return 1;
148 }
149
150 static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
151 {
152 struct private_alsa_write_data *pad = wn->private_data;
153 struct writer_node_group *wng = wn->wng;
154 struct timeval tv;
155 snd_pcm_sframes_t avail, underrun;
156
157 if (!pad->handle)
158 return 1;
159 if (*wng->loaded - wn->written < pad->bytes_per_frame)
160 return 1;
161 /*
162 * Data is available to be written to the alsa handle. Compute number
163 * of milliseconds until next buffer underrun would occur.
164 *
165 * snd_pcm_avail_update() updates the current available count of
166 * samples for writing. It is a light method to obtain current stream
167 * position, because it does not require the user <-> kernel context
168 * switch, but the value is less accurate, because ring buffer pointers
169 * are updated in kernel drivers only when an interrupt occurs.
170 */
171 avail = snd_pcm_avail_update(pad->handle);
172 if (avail < 0)
173 avail = 0;
174 underrun = (pad->buffer_frames - avail) * pad->buffer_time
175 / pad->buffer_frames / 1000;
176 if (underrun < 50)
177 underrun = 50;
178 underrun -= 50;
179 ms2tv(underrun, &tv);
180 if (tv_diff(&s->timeout, &tv, NULL) > 0)
181 s->timeout = tv;
182 return 1;
183 }
184
185 static void xrun(snd_pcm_t *handle)
186 {
187 snd_pcm_status_t *status;
188 int ret;
189 struct timeval tv, diff;
190
191 snd_pcm_status_alloca(&status);
192 ret = snd_pcm_status(handle, status);
193 if (ret < 0)
194 return;
195 if (snd_pcm_status_get_state(status) != SND_PCM_STATE_XRUN)
196 return;
197 snd_pcm_status_get_trigger_tstamp(status, &tv);
198 tv_diff(now, &tv, &diff);
199 PARA_WARNING_LOG("underrun: %lums\n", tv2ms(&diff));
200 }
201
202 static int alsa_write_post_select(__a_unused struct sched *s,
203 struct writer_node *wn)
204 {
205 struct private_alsa_write_data *pad = wn->private_data;
206 struct writer_node_group *wng = wn->wng;
207 size_t bytes = *wng->loaded - wn->written;
208 unsigned char *data = (unsigned char*)*wng->bufp + wn->written;
209 snd_pcm_sframes_t ret, frames, avail;
210
211 if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) {
212 wn->written = *wng->loaded;
213 return *wng->input_error;
214 }
215 if (!bytes) /* no data available */
216 return 0;
217 if (!pad->handle) {
218 int err = alsa_init(pad, wn->conf);
219 if (err < 0)
220 return err;
221 }
222 frames = bytes / pad->bytes_per_frame;
223 if (!frames) /* less than a single frame available */
224 return 0;
225 avail = snd_pcm_avail_update(pad->handle);
226 if (avail <= 0)
227 return 0;
228 frames = PARA_MIN(frames, avail);
229 ret = snd_pcm_writei(pad->handle, data, frames);
230 if (ret >= 0) {
231 wn->written += ret * pad->bytes_per_frame;
232 return 1;
233 }
234 if (ret == -EPIPE) {
235 xrun(pad->handle);
236 snd_pcm_prepare(pad->handle);
237 return 0;
238 }
239 PARA_WARNING_LOG("%s\n", snd_strerror(-ret));
240 if (ret == -EAGAIN)
241 return 0;
242 return -E_ALSA_WRITE;
243 }
244
245 static void alsa_close(struct writer_node *wn)
246 {
247 struct private_alsa_write_data *pad = wn->private_data;
248 PARA_INFO_LOG("closing writer node %p\n", wn);
249
250 if (pad->handle) {
251 snd_pcm_drain(pad->handle);
252 snd_pcm_close(pad->handle);
253 snd_config_update_free_global();
254 }
255 free(pad);
256 }
257
258 __malloc static void *alsa_parse_config(const char *options)
259 {
260 int ret;
261 struct alsa_write_args_info *conf
262 = para_calloc(sizeof(struct alsa_write_args_info));
263
264 PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
265 ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
266 if (ret)
267 goto err_out;
268 PARA_INFO_LOG("help given: %d\n", conf->help_given);
269 return conf;
270 err_out:
271 free(conf);
272 return NULL;
273 }
274
275 /**
276 * the init function of the alsa writer
277 *
278 * \param w pointer to the writer to initialize
279 *
280 * \sa struct writer
281 */
282 void alsa_write_init(struct writer *w)
283 {
284 struct alsa_write_args_info dummy;
285
286 alsa_cmdline_parser_init(&dummy);
287 w->open = alsa_open;
288 w->close = alsa_close;
289 w->pre_select = alsa_write_pre_select;
290 w->post_select = alsa_write_post_select;
291 w->parse_config = alsa_parse_config;
292 w->shutdown = NULL; /* nothing to do */
293 w->help = (struct ggo_help) {
294 .short_help = alsa_write_args_info_help,
295 .detailed_help = alsa_write_args_info_detailed_help
296 };
297 alsa_cmdline_parser_free(&dummy);
298 }