2 * Copyright (C) 2005-2009 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>
27 #include "alsa_write.cmdline.h"
30 /** always use 16 bit little endian */
31 #define FORMAT SND_PCM_FORMAT_S16_LE
33 /** Data specific to the alsa writer. */
34 struct private_alsa_write_data {
35 /** The alsa handle */
37 /** Determined and set by alsa_open(). */
39 /** Don't write anything until this time. */
40 struct timeval next_chunk;
41 /** The approximate maximum buffer duration in us. */
44 * The samplerate given by command line option or the decoder
45 * of the writer node group.
49 * The number of channels, given by command line option or the
50 * decoder of the writer node group.
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)
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;
65 err = snd_pcm_open(&pad->handle, conf->device_arg,
66 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
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,
81 return -E_CHANNEL_COUNT;
82 if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
83 &pad->samplerate, 0) < 0)
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)
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,
98 if (period_size == buffer_size)
100 snd_pcm_sw_params_current(pad->handle, swparams);
101 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
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,
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)
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");
126 /* Open an instance of the alsa writer. */
127 static int alsa_open(struct writer_node *wn)
129 struct alsa_write_args_info *conf = wn->conf;
130 struct writer_node_group *wng = wn->wng;
131 struct private_alsa_write_data *pad = para_calloc(sizeof(*pad));
133 wn->private_data = pad;
134 if (!conf->samplerate_given && wng->samplerate)
135 pad->samplerate = *wng->samplerate;
137 pad->samplerate = conf->samplerate_arg;
138 if (!conf->channels_given && wng->channels)
139 pad->channels = *wng->channels;
141 pad->channels = conf->channels_arg;
142 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
143 tv_add(now, &(struct timeval){0, 100 * 1000}, &pad->next_chunk);
147 static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
149 struct private_alsa_write_data *pad = wn->private_data;
150 struct writer_node_group *wng = wn->wng;
155 if (tv_diff(now, &pad->next_chunk, &diff) < 0) {
156 if (tv_diff(&s->timeout, &diff, NULL) > 0)
159 s->timeout.tv_sec = 0;
160 s->timeout.tv_usec = 1;
165 static int alsa_write_post_select(__a_unused struct sched *s,
166 struct writer_node *wn)
168 struct private_alsa_write_data *pad = wn->private_data;
169 struct writer_node_group *wng = wn->wng;
170 size_t bytes = *wng->loaded - wn->written;
171 unsigned char *data = (unsigned char*)*wng->bufp + wn->written;
173 snd_pcm_sframes_t ret, frames, avail;
175 if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) {
176 wn->written = *wng->loaded;
177 return *wng->input_error;
179 if (!bytes) /* no data available */
181 if (tv_diff(now, &pad->next_chunk, NULL) < 0)
184 int err = alsa_init(pad, wn->conf);
188 frames = bytes / pad->bytes_per_frame;
189 if (!frames) /* less than a single frame available */
191 avail = snd_pcm_avail_update(pad->handle);
194 frames = PARA_MIN(frames, avail);
195 ret = snd_pcm_writei(pad->handle, data, frames);
197 PARA_WARNING_LOG("%s\n", snd_strerror(-ret));
199 snd_pcm_prepare(pad->handle);
204 return -E_ALSA_WRITE;
206 wn->written += ret * pad->bytes_per_frame;
209 /* wait until 50% buffer space is available */
210 ms2tv(pad->buffer_time / 2000, &tv);
211 tv_add(now, &tv, &pad->next_chunk);
215 static void alsa_close(struct writer_node *wn)
217 struct private_alsa_write_data *pad = wn->private_data;
218 PARA_INFO_LOG("closing writer node %p\n", wn);
221 snd_pcm_drain(pad->handle);
222 snd_pcm_close(pad->handle);
223 snd_config_update_free_global();
228 __malloc static void *alsa_parse_config(const char *options)
231 struct alsa_write_args_info *conf
232 = para_calloc(sizeof(struct alsa_write_args_info));
234 PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
235 ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
238 PARA_INFO_LOG("help given: %d\n", conf->help_given);
246 * the init function of the alsa writer
248 * \param w pointer to the writer to initialize
252 void alsa_write_init(struct writer *w)
254 struct alsa_write_args_info dummy;
256 alsa_cmdline_parser_init(&dummy);
258 w->close = alsa_close;
259 w->pre_select = alsa_write_pre_select;
260 w->post_select = alsa_write_post_select;
261 w->parse_config = alsa_parse_config;
262 w->shutdown = NULL; /* nothing to do */
263 w->help = (struct ggo_help) {
264 .short_help = alsa_write_args_info_help,
265 .detailed_help = alsa_write_args_info_detailed_help
267 alsa_cmdline_parser_free(&dummy);