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.
15 #include <sys/types.h>
17 #include <alsa/asoundlib.h>
26 #include "alsa_write.cmdline.h"
29 /** always use 16 bit little endian */
30 #define FORMAT SND_PCM_FORMAT_S16_LE
32 /** Data specific to the alsa writer. */
33 struct private_alsa_write_data {
34 /** The alsa handle */
36 /** Determined and set by alsa_open(). */
38 /** Don't write anything until this time. */
39 struct timeval next_chunk;
40 /** The approximate maximum buffer duration in us. */
43 * The samplerate given by command line option or the decoder
44 * of the writer node group.
48 * The number of channels, given by command line option or the
49 * decoder of the writer node group.
54 /* Install PCM software and hardware configuration. */
55 static int alsa_init(struct private_alsa_write_data *pad,
56 struct alsa_write_args_info *conf)
58 snd_pcm_hw_params_t *hwparams;
59 snd_pcm_sw_params_t *swparams;
60 snd_pcm_uframes_t buffer_size, start_threshold, stop_threshold;
61 snd_pcm_uframes_t period_size;
64 err = snd_pcm_open(&pad->handle, conf->device_arg,
65 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
69 snd_pcm_hw_params_alloca(&hwparams);
70 snd_pcm_sw_params_alloca(&swparams);
71 if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
72 return -E_BROKEN_CONF;
73 if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
74 SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
75 return -E_ACCESS_TYPE;
76 if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
77 return -E_SAMPLE_FORMAT;
78 if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
80 return -E_CHANNEL_COUNT;
81 if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
82 &pad->samplerate, 0) < 0)
84 err = snd_pcm_hw_params_get_buffer_time_max(hwparams, &pad->buffer_time, 0);
85 if (err < 0 || !pad->buffer_time)
86 return -E_GET_BUFFER_TIME;
87 PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
88 if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
89 &pad->buffer_time, 0) < 0)
90 return -E_SET_BUFFER_TIME;
91 if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
93 snd_pcm_hw_params_get_period_size(hwparams, &period_size, 0);
94 snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
95 PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", buffer_size,
97 if (period_size == buffer_size)
99 snd_pcm_sw_params_current(pad->handle, swparams);
100 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
104 start_threshold = PARA_MIN(buffer_size,
105 (snd_pcm_uframes_t)pad->samplerate);
106 if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
107 start_threshold) < 0)
108 return -E_START_THRESHOLD;
109 stop_threshold = buffer_size;
110 if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
112 return -E_STOP_THRESHOLD;
113 if (snd_pcm_sw_params(pad->handle, swparams) < 0)
114 PARA_WARNING_LOG("unable to install sw params\n");
115 pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
117 if (pad->bytes_per_frame <= 0)
118 return -E_PHYSICAL_WIDTH;
119 PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
120 if (snd_pcm_nonblock(pad->handle, 1))
121 PARA_ERROR_LOG("failed to set nonblock mode\n");
125 /* Open an instance of the alsa writer. */
126 static int alsa_open(struct writer_node *wn)
128 struct alsa_write_args_info *conf = wn->conf;
129 struct writer_node_group *wng = wn->wng;
130 struct private_alsa_write_data *pad = para_calloc(sizeof(*pad));
132 wn->private_data = pad;
133 if (!conf->samplerate_given && wng->samplerate)
134 pad->samplerate = *wng->samplerate;
136 pad->samplerate = conf->samplerate_arg;
137 if (!conf->channels_given && wng->channels)
138 pad->channels = *wng->channels;
140 pad->channels = conf->channels_arg;
141 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
142 tv_add(now, &(struct timeval){0, 100 * 1000}, &pad->next_chunk);
146 static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
148 struct private_alsa_write_data *pad = wn->private_data;
149 struct writer_node_group *wng = wn->wng;
154 if (tv_diff(now, &pad->next_chunk, &diff) < 0) {
155 if (tv_diff(&s->timeout, &diff, NULL) > 0)
158 s->timeout.tv_sec = 0;
159 s->timeout.tv_usec = 1;
164 static int alsa_write_post_select(__a_unused struct sched *s,
165 struct writer_node *wn)
167 struct private_alsa_write_data *pad = wn->private_data;
168 struct writer_node_group *wng = wn->wng;
169 size_t frames, bytes = *wng->loaded - wn->written;
170 unsigned char *data = (unsigned char*)wng->buf + wn->written;
172 snd_pcm_sframes_t ret;
174 if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) {
175 wn->written = *wng->loaded;
176 return *wng->input_error;
178 if (!bytes) /* no data available */
180 if (tv_diff(now, &pad->next_chunk, NULL) < 0)
183 int err = alsa_init(pad, wn->conf);
187 frames = bytes / pad->bytes_per_frame;
188 if (!frames) /* less than a single frame available */
190 ret = snd_pcm_writei(pad->handle, data, frames);
192 PARA_WARNING_LOG("EPIPE\n");
193 snd_pcm_prepare(pad->handle);
196 if (ret < 0 && ret != -EAGAIN) {
197 PARA_WARNING_LOG("alsa error (%zu frames, ret = %d\n",
199 return -E_ALSA_WRITE;
202 PARA_DEBUG_LOG("EAGAIN\n");
204 wn->written += ret * pad->bytes_per_frame;
205 if (ret == frames) /* we wrote everything, try again immediately */
206 pad->next_chunk = *now;
207 else { /* wait until 50% buffer space is available */
208 ms2tv(pad->buffer_time / 2000, &tv);
209 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