1 /* Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
3 /** \file alsa_write.c paraslash's alsa output plugin */
6 * Based in parts on aplay.c from the alsa-utils-1.0.8 package,
7 * Copyright (c) by Jaroslav Kysela <perex@suse.cz>, which is
8 * based on the vplay program by Michael Beck.
12 #include <sys/types.h>
13 #include <alsa/asoundlib.h>
16 #include "write_cmd.lsg.h"
22 #include "buffer_tree.h"
26 /** Data specific to the alsa writer. */
27 struct private_alsa_write_data {
28 /** The alsa handle */
30 /** Determined and set by alsa_init(). */
33 * If the sample rate is not given at the command line and no wav
34 * header was detected, the btr exec mechanism is employed to query the
35 * ancestor buffer tree nodes for this information. In a typical setup
36 * the decoder passes the sample rate back to the alsa writer.
38 * \sa \ref btr_exec_up().
42 * The sample format (8/16 bit, signed/unsigned, little/big endian) is
43 * determined in the same way as the \a sample_rate.
45 snd_pcm_format_t sample_format;
46 /* The number of channels, again determined like \a sample_rate. */
48 /* time until buffer underrun occurs, in milliseconds */
50 struct timeval drain_barrier;
51 /* File descriptor to monitor for reading. */
55 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
58 case SF_S8: return SND_PCM_FORMAT_S8;
59 case SF_U8: return SND_PCM_FORMAT_U8;
60 case SF_S16_LE: return SND_PCM_FORMAT_S16_LE;
61 case SF_S16_BE: return SND_PCM_FORMAT_S16_BE;
62 case SF_U16_LE: return SND_PCM_FORMAT_U16_LE;
63 case SF_U16_BE: return SND_PCM_FORMAT_U16_BE;
64 default: return SND_PCM_FORMAT_S16_LE;
68 /* Install PCM software and hardware configuration. */
69 static int alsa_init(struct writer_node *wn)
71 struct private_alsa_write_data *pad = wn->private_data;
72 snd_pcm_hw_params_t *hwparams = NULL;
73 snd_pcm_sw_params_t *swparams = NULL;
74 snd_pcm_uframes_t start_threshold, stop_threshold;
75 snd_pcm_uframes_t buffer_size, period_size;
76 snd_output_t *output_log;
78 const char *msg, *dev = WRITE_CMD_OPT_STRING_VAL(ALSA, DEVICE, wn->lpr);
81 PARA_INFO_LOG("opening %s\n", dev);
82 msg = "unable to open pcm";
83 ret = snd_pcm_open(&pad->handle, dev, SND_PCM_STREAM_PLAYBACK,
87 ret = snd_pcm_hw_params_malloc(&hwparams);
89 msg = "Broken alsa configuration";
90 ret = snd_pcm_hw_params_any(pad->handle, hwparams);
93 msg = "access type not available";
94 ret = snd_pcm_hw_params_set_access(pad->handle, hwparams,
95 SND_PCM_ACCESS_RW_INTERLEAVED);
98 msg = "sample format not available";
99 ret = snd_pcm_hw_params_set_format(pad->handle, hwparams,
103 msg = "channels count not available";
104 ret = snd_pcm_hw_params_set_channels(pad->handle, hwparams,
108 msg = "could not set sample rate";
109 ret = snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
110 &pad->sample_rate, NULL);
113 /* alsa wants microseconds */
114 pad->buffer_time = 1000U * WRITE_CMD_OPT_UINT32_VAL(ALSA, BUFFER_TIME,
116 msg = "could not set buffer time";
117 ret = snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
118 &pad->buffer_time, NULL);
121 pad->buffer_time /= 1000; /* we prefer milliseconds */
122 period_time = pad->buffer_time * 250; /* buffer time / 4 */
123 msg = "could not set period time";
124 ret = snd_pcm_hw_params_set_period_time_near(pad->handle, hwparams,
129 msg = "unable to install hw params";
130 ret = snd_pcm_hw_params(pad->handle, hwparams);
133 snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
134 snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
135 msg = "period size equals buffer size";
136 if (period_size == buffer_size)
139 /* software parameter setup */
140 ret = snd_pcm_sw_params_malloc(&swparams);
142 snd_pcm_sw_params_current(pad->handle, swparams);
143 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
147 start_threshold = PARA_MIN(buffer_size,
148 (snd_pcm_uframes_t)pad->sample_rate);
149 msg = "could not set start threshold";
150 ret = snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
154 stop_threshold = buffer_size;
155 msg = "could not set stop threshold";
156 ret = snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
160 msg = "unable to install sw params";
161 ret = snd_pcm_sw_params(pad->handle, swparams);
164 msg = "unable to determine bytes per frame";
165 ret = snd_pcm_format_physical_width(pad->sample_format);
168 pad->bytes_per_frame = ret * pad->channels / 8;
169 msg = "failed to set alsa handle to nonblock mode";
170 ret = snd_pcm_nonblock(pad->handle, 1);
173 ret = snd_output_buffer_open(&output_log);
177 PARA_DEBUG_LOG("dumping alsa configuration\n");
178 snd_pcm_dump(pad->handle, output_log);
179 snd_pcm_hw_params_dump(hwparams, output_log);
180 sz = snd_output_buffer_string(output_log, &buf);
181 for (p = buf; p < buf + sz;) {
182 char *q = memchr(p, '\n', buf + sz - p);
186 PARA_DEBUG_LOG("%s\n", p);
189 snd_output_close(output_log);
195 PARA_ERROR_LOG("%s: %s\n", msg, snd_strerror(-ret));
197 PARA_ERROR_LOG("%s\n", msg);
200 snd_pcm_hw_params_free(hwparams);
201 snd_pcm_sw_params_free(swparams);
205 static void alsa_write_pre_monitor(struct sched *s, void *context)
208 struct writer_node *wn = context;
209 struct private_alsa_write_data *pad = wn->private_data;
210 int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
221 sched_request_barrier_or_min_delay(&pad->drain_barrier, s);
224 /* wait at most 50% of the buffer time */
225 sched_request_timeout_ms(pad->buffer_time / 2, s);
226 ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1);
228 PARA_ERROR_LOG("could not get alsa poll fd: %s\n",
232 pad->poll_fd = pfd.fd;
233 sched_monitor_readfd(pfd.fd, s);
236 static void alsa_close(struct writer_node *wn)
238 struct private_alsa_write_data *pad = wn->private_data;
239 PARA_INFO_LOG("closing writer node %p\n", wn);
246 * It's OK to have a blocking operation here because we already made
247 * sure that the PCM output buffer is (nearly) empty.
249 snd_pcm_nonblock(pad->handle, 0);
250 snd_pcm_drain(pad->handle);
251 snd_pcm_close(pad->handle);
252 snd_config_update_free_global();
257 static int alsa_write_post_monitor(__a_unused struct sched *s, void *context)
259 struct writer_node *wn = context;
260 struct private_alsa_write_data *pad = wn->private_data;
261 struct btr_node *btrn = wn->btrn;
264 snd_pcm_sframes_t frames;
267 ret = task_get_notification(wn->task);
271 ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
276 btr_merge(btrn, wn->min_iqs);
277 bytes = btr_next_buffer(btrn, &data);
278 if (ret < 0 || bytes < wn->min_iqs) { /* eof */
279 assert(btr_no_parent(btrn));
280 ret = -E_WRITE_COMMON_EOF;
283 /* wait until pending frames are played */
284 if (pad->drain_barrier.tv_sec == 0) {
285 PARA_DEBUG_LOG("waiting for device to drain\n");
286 tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
287 &pad->drain_barrier);
290 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
297 if (bytes == 0) /* no data available */
299 pad = wn->private_data = zalloc(sizeof(*pad));
300 ret = get_btr_sample_rate(btrn, &val);
303 pad->sample_rate = val;
304 ret = get_btr_channels(btrn, &val);
308 ret = get_btr_sample_format(btrn, &val);
311 pad->sample_format = get_alsa_pcm_format(val);
312 PARA_INFO_LOG("%u channel(s), %uHz\n", pad->channels,
317 wn->min_iqs = pad->bytes_per_frame;
320 frames = bytes / pad->bytes_per_frame;
321 frames = snd_pcm_writei(pad->handle, data, frames);
322 if (frames == 0 || frames == -EAGAIN) {
324 if (pad->poll_fd >= 0 && sched_read_ok(pad->poll_fd, s))
325 if (read(pad->poll_fd, buf, 100))
330 btr_consume(btrn, frames * pad->bytes_per_frame);
333 if (frames == -EPIPE) {
334 snd_pcm_status_t *status;
335 snd_pcm_status_malloc(&status);
336 if (snd_pcm_status_get_state(status) == SND_PCM_STATE_XRUN)
337 PARA_WARNING_LOG("underrun\n");
338 snd_pcm_status_free(status);
339 snd_pcm_prepare(pad->handle);
342 PARA_ERROR_LOG("alsa write error: %s\n", snd_strerror(-frames));
346 btr_remove_node(&wn->btrn);
350 struct writer lsg_write_cmd_com_alsa_user_data = {
352 .pre_monitor = alsa_write_pre_monitor,
353 .post_monitor = alsa_write_post_monitor,