alsa_write.c: Add missing documentation
[paraslash.git] / alsa_write.c
1 /*
2 * Copyright (C) 2005-2006 Andre Noll <maan@systemlinux.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
17 */
18
19 /** \file alsa_write.c paraslash's alsa output plugin */
20
21 /*
22 * Based in parts on aplay.c from the alsa-utils-1.0.8 package,
23 * Copyright (c) by Jaroslav Kysela <perex@suse.cz>, which is
24 * based on the vplay program by Michael Beck.
25 */
26
27 #include "para.h"
28 #include "fd.h"
29 #include "string.h"
30 #include "list.h"
31 #include "sched.h"
32 #include "write.h"
33
34 #include <alsa/asoundlib.h>
35
36 #include "alsa_write.cmdline.h"
37 #include "error.h"
38
39 /** always use 16 bit little endian */
40 #define FORMAT SND_PCM_FORMAT_S16_LE
41
42 /** data specific to the alsa writer */
43 struct private_alsa_write_data {
44 /** the alsa handle */
45 snd_pcm_t *handle;
46 /** determined and set by alsa_open() */
47 size_t bytes_per_frame;
48 /** don't write anything until this time */
49 struct timeval next_chunk;
50 /** the return value of snd_pcm_hw_params_get_buffer_time_max() */
51 unsigned buffer_time;
52 /**
53 * the samplerate given by command line option or the decoder
54 * of the writer node group
55 */
56 unsigned samplerate;
57 /**
58 * the number of channels, also given by command line option or the
59 * decoder of the writer node group
60 */
61 unsigned channels;
62 };
63
64 /*
65 * open and prepare the PCM handle for writing
66 *
67 * Install PCM software and hardware configuration. Exit on errors.
68 */
69 static int alsa_open(struct writer_node *w)
70 {
71 snd_pcm_hw_params_t *hwparams;
72 snd_pcm_sw_params_t *swparams;
73 snd_pcm_uframes_t buffer_size, xfer_align, start_threshold,
74 stop_threshold;
75 int err;
76 snd_pcm_info_t *info;
77 snd_pcm_uframes_t period_size;
78 struct private_alsa_write_data *pad = para_calloc(sizeof(struct
79 private_alsa_write_data));
80 struct alsa_write_args_info *conf = w->conf;
81 struct writer_node_group *wng = w->wng;
82
83 if (!conf->samplerate_given && wng->samplerate)
84 pad->samplerate = *wng->samplerate;
85 else
86 pad->samplerate = conf->samplerate_arg;
87 if (!conf->channels_given && wng->channels)
88 pad->channels = *wng->channels;
89 else
90 pad->channels = conf->channels_arg;
91 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
92 w->private_data = pad;
93 snd_pcm_info_alloca(&info);
94 err = snd_pcm_open(&pad->handle, conf->device_arg,
95 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
96 if (err < 0)
97 return -E_PCM_OPEN;
98 if ((err = snd_pcm_info(pad->handle, info)) < 0)
99 return -E_SND_PCM_INFO;
100
101 snd_pcm_hw_params_alloca(&hwparams);
102 snd_pcm_sw_params_alloca(&swparams);
103 if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
104 return -E_BROKEN_CONF;
105 if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
106 SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
107 return -E_ACCESS_TYPE;
108 if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
109 return -E_SAMPLE_FORMAT;
110 if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
111 pad->channels) < 0)
112 return -E_CHANNEL_COUNT;
113 if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
114 &pad->samplerate, 0) < 0)
115 return -E_SET_RATE;
116 err = snd_pcm_hw_params_get_buffer_time_max(hwparams, &pad->buffer_time, 0);
117 if (err < 0 || !pad->buffer_time)
118 return -E_GET_BUFFER_TIME;
119 PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
120 if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
121 &pad->buffer_time, 0) < 0)
122 return -E_SET_BUFFER_TIME;
123 if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
124 return -E_HW_PARAMS;
125 snd_pcm_hw_params_get_period_size(hwparams, &period_size, 0);
126 snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
127 PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", buffer_size,
128 period_size);
129 if (period_size == buffer_size)
130 return -E_BAD_PERIOD;
131 snd_pcm_sw_params_current(pad->handle, swparams);
132 err = snd_pcm_sw_params_get_xfer_align(swparams, &xfer_align);
133 if (err < 0 || !xfer_align)
134 return -E_GET_XFER;
135 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
136 /* round to closest transfer boundary */
137 start_threshold = (buffer_size / xfer_align) * xfer_align;
138 if (start_threshold < 1)
139 start_threshold = 1;
140 if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
141 start_threshold) < 0)
142 return -E_START_THRESHOLD;
143 stop_threshold = buffer_size;
144 if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
145 stop_threshold) < 0)
146 return -E_STOP_THRESHOLD;
147 if (snd_pcm_sw_params_set_xfer_align(pad->handle, swparams,
148 xfer_align) < 0)
149 return -E_SET_XFER;
150 if (snd_pcm_sw_params(pad->handle, swparams) < 0)
151 return -E_SW_PARAMS;
152 pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
153 * pad->channels / 8;
154 if (snd_pcm_nonblock(pad->handle, 1))
155 PARA_ERROR_LOG("%s\n", "failed to set nonblock mode");
156 return period_size * pad->bytes_per_frame;
157 }
158
159 static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
160 {
161 struct private_alsa_write_data *pad = wn->private_data;
162 struct writer_node_group *wng = wn->wng;
163 struct timeval diff;
164
165 if (*wng->loaded < pad->bytes_per_frame)
166 return 1;
167 if (tv_diff(now, &pad->next_chunk, &diff) < 0) {
168 if (tv_diff(&s->timeout, &diff, NULL) > 0)
169 s->timeout = diff;
170 } else {
171 s->timeout.tv_sec = 0;
172 s->timeout.tv_usec = 1;
173 }
174 return 1;
175 // PARA_INFO_LOG("timeout: %lu\n", tv2ms(&s->timeout));
176 }
177
178 static int alsa_write_post_select(__a_unused struct sched *s,
179 struct writer_node *wn)
180 {
181 struct private_alsa_write_data *pad = wn->private_data;
182 struct writer_node_group *wng = wn->wng;
183 size_t frames = (*wng->loaded - wn->written) / pad->bytes_per_frame;
184 snd_pcm_sframes_t ret;
185 unsigned char *data = (unsigned char*)wng->buf + wn->written;
186 struct timeval tv;
187
188 // PARA_INFO_LOG("%zd frames\n", frames);
189 if (!frames) {
190 if (*wng->input_eof)
191 wn->written = *wng->loaded;
192 return 1;
193 }
194 if (tv_diff(now, &pad->next_chunk, NULL) < 0)
195 return 1;
196 ret = snd_pcm_writei(pad->handle, data, frames);
197 if (ret == -EPIPE) {
198 PARA_WARNING_LOG("%s", "EPIPE\n");
199 snd_pcm_prepare(pad->handle);
200 return 1;
201 }
202 if (ret < 0) {
203 PARA_WARNING_LOG("%s", "ALSA ERROR\n");
204 return -E_ALSA_WRITE;
205 }
206 ms2tv(pad->buffer_time / 4000, &tv);
207 // ms2tv(1, &tv);
208 tv_add(now, &tv, &pad->next_chunk);
209 wn->written += ret * pad->bytes_per_frame;
210 return 1;
211 }
212
213 static void alsa_close(struct writer_node *wn)
214 {
215 struct private_alsa_write_data *pad = wn->private_data;
216 PARA_INFO_LOG("closing writer node %p\n", wn);
217 snd_pcm_drain(pad->handle);
218 snd_pcm_close(pad->handle);
219 snd_config_update_free_global();
220 free(pad);
221 }
222
223 __malloc static void *alsa_parse_config(const char *options)
224 {
225 struct alsa_write_args_info *conf
226 = para_calloc(sizeof(struct alsa_write_args_info));
227 PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
228 int ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
229 if (ret)
230 goto err_out;
231 PARA_INFO_LOG("help given: %d\n", conf->help_given);
232 return conf;
233 err_out:
234 free(conf);
235 return NULL;
236 }
237
238 /**
239 * the init function of the alsa writer
240 *
241 * \param w pointer to the writer to initialize
242 *
243 * \sa struct writer
244 */
245 void alsa_write_init(struct writer *w)
246 {
247 w->open = alsa_open;
248 w->close = alsa_close;
249 w->pre_select = alsa_write_pre_select;
250 w->post_select = alsa_write_post_select;
251 w->parse_config = alsa_parse_config;
252 w->shutdown = NULL; /* nothing to do */
253 }