2 * Copyright (C) 2005-2010 Andre Noll <maan@systemlinux.org>
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>
18 #include <alsa/asoundlib.h>
28 #include "buffer_tree.h"
30 #include "write_common.h"
31 #include "alsa_write.cmdline.h"
34 /** Data specific to the alsa writer. */
35 struct private_alsa_write_data {
36 /** The alsa handle */
38 /** Determined and set by alsa_open(). */
40 /** The approximate maximum buffer duration in us. */
42 /* Number of frames that fit into the buffer. */
43 snd_pcm_uframes_t buffer_frames;
45 * The sample rate given by command line option or the decoder
46 * of the writer node group.
49 snd_pcm_format_t sample_format;
51 * The number of channels, given by command line option or the
52 * decoder of the writer node group.
55 struct timeval drain_barrier;
58 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
61 case SF_S8: return SND_PCM_FORMAT_S8;
62 case SF_U8: return SND_PCM_FORMAT_U8;
63 case SF_S16_LE: return SND_PCM_FORMAT_S16_LE;
64 case SF_S16_BE: return SND_PCM_FORMAT_S16_BE;
65 case SF_U16_LE: return SND_PCM_FORMAT_U16_LE;
66 case SF_U16_BE: return SND_PCM_FORMAT_U16_BE;
67 default: return SND_PCM_FORMAT_S16_LE;
71 /* Install PCM software and hardware configuration. */
72 static int alsa_init(struct private_alsa_write_data *pad,
73 struct alsa_write_args_info *conf)
75 snd_pcm_hw_params_t *hwparams;
76 snd_pcm_sw_params_t *swparams;
77 snd_pcm_uframes_t start_threshold, stop_threshold;
78 snd_pcm_uframes_t period_size;
81 PARA_INFO_LOG("opening %s\n", conf->device_arg);
82 err = snd_pcm_open(&pad->handle, conf->device_arg,
83 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
87 snd_pcm_hw_params_alloca(&hwparams);
88 snd_pcm_sw_params_alloca(&swparams);
89 if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
90 return -E_BROKEN_CONF;
91 if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
92 SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
93 return -E_ACCESS_TYPE;
94 if (snd_pcm_hw_params_set_format(pad->handle, hwparams,
95 pad->sample_format) < 0)
96 return -E_SAMPLE_FORMAT;
97 if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
99 return -E_CHANNEL_COUNT;
100 if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
101 &pad->sample_rate, NULL) < 0)
103 err = snd_pcm_hw_params_get_buffer_time_max(hwparams,
104 &pad->buffer_time, NULL);
105 if (err < 0 || !pad->buffer_time)
106 return -E_GET_BUFFER_TIME;
107 PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
108 if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
109 &pad->buffer_time, NULL) < 0)
110 return -E_SET_BUFFER_TIME;
111 if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
113 snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
114 snd_pcm_hw_params_get_buffer_size(hwparams, &pad->buffer_frames);
115 PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad->buffer_frames,
117 if (period_size == pad->buffer_frames)
118 return -E_BAD_PERIOD;
119 snd_pcm_sw_params_current(pad->handle, swparams);
120 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
121 if (pad->buffer_frames < 1)
124 start_threshold = PARA_MIN(pad->buffer_frames,
125 (snd_pcm_uframes_t)pad->sample_rate);
126 if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
127 start_threshold) < 0)
128 return -E_START_THRESHOLD;
129 stop_threshold = pad->buffer_frames;
130 if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
132 return -E_STOP_THRESHOLD;
133 if (snd_pcm_sw_params(pad->handle, swparams) < 0)
134 PARA_WARNING_LOG("unable to install sw params\n");
135 pad->bytes_per_frame = snd_pcm_format_physical_width(pad->sample_format)
137 if (pad->bytes_per_frame <= 0)
138 return -E_PHYSICAL_WIDTH;
139 PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
140 if (snd_pcm_nonblock(pad->handle, 1))
141 PARA_ERROR_LOG("failed to set nonblock mode\n");
145 /* Open an instance of the alsa writer. */
146 static int alsa_open(struct writer_node *wn)
148 wn->private_data = para_calloc(sizeof(struct private_alsa_write_data));
152 static void alsa_write_pre_select(struct sched *s, struct task *t)
154 struct writer_node *wn = container_of(t, struct writer_node, task);
155 struct private_alsa_write_data *pad = wn->private_data;
157 snd_pcm_sframes_t avail, underrun;
162 ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
164 sched_request_timeout_ms(20, s);
168 * Data is available to be written to the alsa handle. Compute number
169 * of milliseconds until next buffer underrun would occur.
171 * snd_pcm_avail_update() updates the current available count of
172 * samples for writing. It is a light method to obtain current stream
173 * position, because it does not require the user <-> kernel context
174 * switch, but the value is less accurate, because ring buffer pointers
175 * are updated in kernel drivers only when an interrupt occurs.
177 avail = snd_pcm_avail_update(pad->handle);
180 underrun = (pad->buffer_frames - avail) * pad->buffer_time
181 / pad->buffer_frames / 1000;
185 ms2tv(underrun, &tv);
186 sched_request_timeout(&tv, s);
189 static void alsa_close(struct writer_node *wn)
191 struct private_alsa_write_data *pad = wn->private_data;
192 PARA_INFO_LOG("closing writer node %p\n", wn);
196 * It's OK to have a blocking operation here because we already
197 * made sure that the PCM output buffer is (nearly) empty.
199 snd_pcm_nonblock(pad->handle, 0);
200 snd_pcm_drain(pad->handle);
201 snd_pcm_close(pad->handle);
202 snd_config_update_free_global();
207 static void alsa_write_post_select(__a_unused struct sched *s,
210 struct writer_node *wn = container_of(t, struct writer_node, task);
211 struct private_alsa_write_data *pad = wn->private_data;
212 struct btr_node *btrn = wn->btrn;
215 snd_pcm_sframes_t frames;
220 ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
223 btr_merge(btrn, wn->min_iqs);
224 bytes = btr_next_buffer(btrn, &data);
225 if (ret < 0 || bytes < pad->bytes_per_frame) { /* eof */
226 assert(btr_no_parent(btrn));
230 /* wait until pending frames are played */
231 if (pad->drain_barrier.tv_sec == 0) {
232 PARA_DEBUG_LOG("waiting for device to drain\n");
233 tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
234 &pad->drain_barrier);
237 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
244 if (bytes == 0) /* no data available */
246 get_btr_sample_rate(btrn, &val);
247 pad->sample_rate = val;
248 get_btr_channels(btrn, &val);
250 get_btr_sample_format(btrn, &val);
251 pad->sample_format = get_alsa_pcm_format(val);
253 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
255 ret = alsa_init(pad, wn->conf);
258 wn->min_iqs = pad->bytes_per_frame;
261 frames = bytes / pad->bytes_per_frame;
262 frames = snd_pcm_writei(pad->handle, data, frames);
264 btr_consume(btrn, frames * pad->bytes_per_frame);
267 if (frames == -EPIPE) {
268 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
269 snd_pcm_prepare(pad->handle);
272 if (frames == -EAGAIN)
274 PARA_WARNING_LOG("%s\n", snd_strerror(-frames));
278 btr_remove_node(btrn);
282 __malloc static void *alsa_parse_config_or_die(const char *options)
284 struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
286 PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
287 /* exits on errors */
288 alsa_cmdline_parser_string(options, conf, "alsa_write");
292 static void alsa_free_config(void *conf)
294 alsa_cmdline_parser_free(conf);
298 * The init function of the alsa writer.
300 * \param w Pointer to the writer to initialize.
302 * \sa struct \ref writer.
304 void alsa_write_init(struct writer *w)
306 struct alsa_write_args_info dummy;
308 alsa_cmdline_parser_init(&dummy);
310 w->close = alsa_close;
311 w->pre_select = alsa_write_pre_select;
312 w->post_select = alsa_write_post_select;
313 w->parse_config_or_die = alsa_parse_config_or_die;
314 w->shutdown = NULL; /* nothing to do */
315 w->free_config = alsa_free_config;
316 w->help = (struct ggo_help) {
317 .short_help = alsa_write_args_info_help,
318 .detailed_help = alsa_write_args_info_detailed_help
320 alsa_cmdline_parser_free(&dummy);