2 * Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file alsa_write.c paraslash's alsa output plugin */
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.
16 #include <sys/types.h>
17 #include <alsa/asoundlib.h>
25 #include "buffer_tree.h"
27 #include "write_common.h"
28 #include "alsa_write.cmdline.h"
31 /** Data specific to the alsa writer. */
32 struct private_alsa_write_data {
33 /** The alsa handle */
35 /** Determined and set by alsa_init(). */
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.
43 * \sa \ref btr_exec_up().
47 * The sample format (8/16 bit, signed/unsigned, little/big endian) is
48 * determined in the same way as the \a sample_rate.
50 snd_pcm_format_t sample_format;
51 /* The number of channels, again determined like \a sample_rate. */
53 /* time until buffer underrun occurs, in milliseconds */
55 struct timeval drain_barrier;
56 /* File descriptor for select(). */
60 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format 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;
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)
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;
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);
92 snd_pcm_hw_params_alloca(&hwparams);
93 msg = "Broken alsa configuration";
94 ret = snd_pcm_hw_params_any(pad->handle, hwparams);
97 msg = "access type not available";
98 ret = snd_pcm_hw_params_set_access(pad->handle, hwparams,
99 SND_PCM_ACCESS_RW_INTERLEAVED);
102 msg = "sample format not available";
103 ret = snd_pcm_hw_params_set_format(pad->handle, hwparams,
107 msg = "channels count not available";
108 ret = snd_pcm_hw_params_set_channels(pad->handle, hwparams,
112 msg = "could not set sample rate";
113 ret = snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
114 &pad->sample_rate, NULL);
117 /* alsa wants microseconds */
118 pad->buffer_time = conf->buffer_time_arg * 1000;
119 msg = "could not set buffer time";
120 ret = snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
121 &pad->buffer_time, NULL);
124 pad->buffer_time /= 1000; /* we prefer milliseconds */
125 period_time = pad->buffer_time * 250; /* buffer time / 4 */
126 msg = "could not set period time";
127 ret = snd_pcm_hw_params_set_period_time_near(pad->handle, hwparams,
132 msg = "unable to install hw params";
133 ret = snd_pcm_hw_params(pad->handle, hwparams);
136 snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
137 snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
138 msg = "period size equals buffer size";
139 if (period_size == buffer_size)
142 /* software parameter setup */
143 snd_pcm_sw_params_alloca(&swparams);
144 snd_pcm_sw_params_current(pad->handle, swparams);
145 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
149 start_threshold = PARA_MIN(buffer_size,
150 (snd_pcm_uframes_t)pad->sample_rate);
151 msg = "could not set start threshold";
152 ret = snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
156 stop_threshold = buffer_size;
157 msg = "could not set stop threshold";
158 ret = snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
162 msg = "unable to install sw params";
163 ret = snd_pcm_sw_params(pad->handle, swparams);
166 msg = "unable to determine bytes per frame";
167 ret = snd_pcm_format_physical_width(pad->sample_format);
170 pad->bytes_per_frame = ret * pad->channels / 8;
171 msg = "failed to set alsa handle to nonblock mode";
172 ret = snd_pcm_nonblock(pad->handle, 1);
175 ret = snd_output_buffer_open(&output_log);
179 PARA_DEBUG_LOG("dumping alsa configuration\n");
180 snd_pcm_dump(pad->handle, output_log);
181 snd_pcm_hw_params_dump(hwparams, output_log);
182 sz = snd_output_buffer_string(output_log, &buf);
183 for (p = buf; p < buf + sz;) {
184 char *q = memchr(p, '\n', buf + sz - p);
188 PARA_DEBUG_LOG("%s\n", p);
191 snd_output_close(output_log);
196 PARA_ERROR_LOG("%s: %s\n", msg, snd_strerror(-ret));
198 PARA_ERROR_LOG("%s\n", msg);
202 static void alsa_write_pre_select(struct sched *s, void *context)
205 struct writer_node *wn = context;
206 struct private_alsa_write_data *pad = wn->private_data;
207 int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
218 sched_request_barrier_or_min_delay(&pad->drain_barrier, s);
221 /* wait at most 50% of the buffer time */
222 sched_request_timeout_ms(pad->buffer_time / 2, s);
223 ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1);
225 PARA_ERROR_LOG("could not get alsa poll fd: %s\n",
229 pad->poll_fd = pfd.fd;
230 para_fd_set(pfd.fd, &s->rfds, &s->max_fileno);
233 static void alsa_close(struct writer_node *wn)
235 struct private_alsa_write_data *pad = wn->private_data;
236 PARA_INFO_LOG("closing writer node %p\n", wn);
241 * It's OK to have a blocking operation here because we already made
242 * sure that the PCM output buffer is (nearly) empty.
244 snd_pcm_nonblock(pad->handle, 0);
245 snd_pcm_drain(pad->handle);
246 snd_pcm_close(pad->handle);
247 snd_config_update_free_global();
251 static int alsa_write_post_select(__a_unused struct sched *s, void *context)
253 struct writer_node *wn = context;
254 struct private_alsa_write_data *pad = wn->private_data;
255 struct btr_node *btrn = wn->btrn;
258 snd_pcm_sframes_t frames;
261 ret = task_get_notification(wn->task);
265 ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
268 btr_merge(btrn, wn->min_iqs);
269 bytes = btr_next_buffer(btrn, &data);
270 if (ret < 0 || bytes < wn->min_iqs) { /* eof */
271 assert(btr_no_parent(btrn));
272 ret = -E_WRITE_COMMON_EOF;
275 /* wait until pending frames are played */
276 if (pad->drain_barrier.tv_sec == 0) {
277 PARA_DEBUG_LOG("waiting for device to drain\n");
278 tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
279 &pad->drain_barrier);
282 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
289 if (bytes == 0) /* no data available */
291 pad = para_calloc(sizeof(*pad));
292 get_btr_sample_rate(btrn, &val);
293 pad->sample_rate = val;
294 get_btr_channels(btrn, &val);
296 get_btr_sample_format(btrn, &val);
297 pad->sample_format = get_alsa_pcm_format(val);
299 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
301 ret = alsa_init(pad, wn->conf);
306 wn->private_data = pad;
307 wn->min_iqs = pad->bytes_per_frame;
310 frames = bytes / pad->bytes_per_frame;
311 frames = snd_pcm_writei(pad->handle, data, frames);
312 if (frames == 0 || frames == -EAGAIN) {
314 if (pad->poll_fd >= 0 && FD_ISSET(pad->poll_fd, &s->rfds))
315 if (read(pad->poll_fd, buf, 100))
320 btr_consume(btrn, frames * pad->bytes_per_frame);
323 if (frames == -EPIPE) {
324 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
325 snd_pcm_prepare(pad->handle);
328 PARA_ERROR_LOG("alsa write error: %s\n", snd_strerror(-frames));
332 btr_remove_node(&wn->btrn);
336 __malloc static void *alsa_parse_config_or_die(int argc, char **argv)
338 struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
340 /* exits on errors */
341 alsa_write_cmdline_parser(argc, argv, conf);
345 static void alsa_free_config(void *conf)
347 alsa_write_cmdline_parser_free(conf);
351 * The init function of the alsa writer.
353 * \param w Pointer to the writer to initialize.
355 * \sa struct \ref writer.
357 void alsa_write_init(struct writer *w)
359 struct alsa_write_args_info dummy;
361 alsa_write_cmdline_parser_init(&dummy);
362 w->close = alsa_close;
363 w->pre_select = alsa_write_pre_select;
364 w->post_select = alsa_write_post_select;
365 w->parse_config_or_die = alsa_parse_config_or_die;
366 w->free_config = alsa_free_config;
367 w->help = (struct ggo_help)DEFINE_GGO_HELP(alsa_write);
368 alsa_write_cmdline_parser_free(&dummy);