2 * Copyright (C) 2005-2007 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>
25 #include "alsa_write.cmdline.h"
28 /** always use 16 bit little endian */
29 #define FORMAT SND_PCM_FORMAT_S16_LE
31 /** data specific to the alsa writer */
32 struct private_alsa_write_data {
33 /** the alsa handle */
35 /** determined and set by alsa_open() */
36 size_t bytes_per_frame;
37 /** don't write anything until this time */
38 struct timeval next_chunk;
39 /** the return value of snd_pcm_hw_params_get_buffer_time_max() */
42 * the samplerate given by command line option or the decoder
43 * of the writer node group
47 * the number of channels, also given by command line option or the
48 * decoder of the writer node group
54 * open and prepare the PCM handle for writing
56 * Install PCM software and hardware configuration. Exit on errors.
58 static int alsa_open(struct writer_node *w)
60 snd_pcm_hw_params_t *hwparams;
61 snd_pcm_sw_params_t *swparams;
62 snd_pcm_uframes_t buffer_size, xfer_align, start_threshold,
66 snd_pcm_uframes_t period_size;
67 struct private_alsa_write_data *pad = para_calloc(sizeof(struct
68 private_alsa_write_data));
69 struct alsa_write_args_info *conf = w->conf;
70 struct writer_node_group *wng = w->wng;
72 if (!conf->samplerate_given && wng->samplerate)
73 pad->samplerate = *wng->samplerate;
75 pad->samplerate = conf->samplerate_arg;
76 if (!conf->channels_given && wng->channels)
77 pad->channels = *wng->channels;
79 pad->channels = conf->channels_arg;
80 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
81 w->private_data = pad;
82 snd_pcm_info_alloca(&info);
83 err = snd_pcm_open(&pad->handle, conf->device_arg,
84 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
87 if ((err = snd_pcm_info(pad->handle, info)) < 0)
88 return -E_SND_PCM_INFO;
90 snd_pcm_hw_params_alloca(&hwparams);
91 snd_pcm_sw_params_alloca(&swparams);
92 if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
93 return -E_BROKEN_CONF;
94 if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
95 SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
96 return -E_ACCESS_TYPE;
97 if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
98 return -E_SAMPLE_FORMAT;
99 if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
101 return -E_CHANNEL_COUNT;
102 if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
103 &pad->samplerate, 0) < 0)
105 err = snd_pcm_hw_params_get_buffer_time_max(hwparams, &pad->buffer_time, 0);
106 if (err < 0 || !pad->buffer_time)
107 return -E_GET_BUFFER_TIME;
108 PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
109 if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
110 &pad->buffer_time, 0) < 0)
111 return -E_SET_BUFFER_TIME;
112 if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
114 snd_pcm_hw_params_get_period_size(hwparams, &period_size, 0);
115 snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
116 PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", buffer_size,
118 if (period_size == buffer_size)
119 return -E_BAD_PERIOD;
120 snd_pcm_sw_params_current(pad->handle, swparams);
121 err = snd_pcm_sw_params_get_xfer_align(swparams, &xfer_align);
122 if (err < 0 || !xfer_align)
124 snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
125 /* round to closest transfer boundary */
126 start_threshold = (buffer_size / xfer_align) * xfer_align;
127 if (start_threshold < 1)
129 if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
130 start_threshold) < 0)
131 return -E_START_THRESHOLD;
132 stop_threshold = buffer_size;
133 if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
135 return -E_STOP_THRESHOLD;
136 if (snd_pcm_sw_params_set_xfer_align(pad->handle, swparams,
139 if (snd_pcm_sw_params(pad->handle, swparams) < 0)
141 pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
143 if (snd_pcm_nonblock(pad->handle, 1))
144 PARA_ERROR_LOG("%s\n", "failed to set nonblock mode");
145 return period_size * pad->bytes_per_frame;
148 static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
150 struct private_alsa_write_data *pad = wn->private_data;
151 struct writer_node_group *wng = wn->wng;
154 if (*wng->loaded < pad->bytes_per_frame)
156 if (tv_diff(now, &pad->next_chunk, &diff) < 0) {
157 if (tv_diff(&s->timeout, &diff, NULL) > 0)
160 s->timeout.tv_sec = 0;
161 s->timeout.tv_usec = 1;
164 // PARA_INFO_LOG("timeout: %lu\n", tv2ms(&s->timeout));
167 static int alsa_write_post_select(__a_unused struct sched *s,
168 struct writer_node *wn)
170 struct private_alsa_write_data *pad = wn->private_data;
171 struct writer_node_group *wng = wn->wng;
172 size_t frames = (*wng->loaded - wn->written) / pad->bytes_per_frame;
173 snd_pcm_sframes_t ret;
174 unsigned char *data = (unsigned char*)wng->buf + wn->written;
177 // PARA_INFO_LOG("%zd frames\n", frames);
180 wn->written = *wng->loaded;
183 if (tv_diff(now, &pad->next_chunk, NULL) < 0)
185 ret = snd_pcm_writei(pad->handle, data, frames);
187 PARA_WARNING_LOG("%s", "EPIPE\n");
188 snd_pcm_prepare(pad->handle);
192 PARA_WARNING_LOG("%s", "ALSA ERROR\n");
193 return -E_ALSA_WRITE;
195 ms2tv(pad->buffer_time / 4000, &tv);
197 tv_add(now, &tv, &pad->next_chunk);
198 wn->written += ret * pad->bytes_per_frame;
202 static void alsa_close(struct writer_node *wn)
204 struct private_alsa_write_data *pad = wn->private_data;
205 PARA_INFO_LOG("closing writer node %p\n", wn);
206 snd_pcm_drain(pad->handle);
207 snd_pcm_close(pad->handle);
208 snd_config_update_free_global();
212 __malloc static void *alsa_parse_config(const char *options)
214 struct alsa_write_args_info *conf
215 = para_calloc(sizeof(struct alsa_write_args_info));
216 PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
217 int ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
220 PARA_INFO_LOG("help given: %d\n", conf->help_given);
228 * the init function of the alsa writer
230 * \param w pointer to the writer to initialize
234 void alsa_write_init(struct writer *w)
237 w->close = alsa_close;
238 w->pre_select = alsa_write_pre_select;
239 w->post_select = alsa_write_post_select;
240 w->parse_config = alsa_parse_config;
241 w->shutdown = NULL; /* nothing to do */