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