alsa_write.c

   1 /*
   2  * Copyright (C) 2005-2011 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file alsa_write.c paraslash's alsa output plugin */
   8
   9 /*
  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.
  13  */
  14
  15 #include <regex.h>
  16 #include <sys/types.h>
  17 #include <alsa/asoundlib.h>
  18 #include <sys/time.h>
  19 #include <stdbool.h>
  20
  21 #include "para.h"
  22 #include "fd.h"
  23 #include "string.h"
  24 #include "list.h"
  25 #include "sched.h"
  26 #include "ggo.h"
  27 #include "buffer_tree.h"
  28 #include "write.h"
  29 #include "write_common.h"
  30 #include "alsa_write.cmdline.h"
  31 #include "error.h"
  32
  33 /** Data specific to the alsa writer. */
  34 struct private_alsa_write_data {
  35         /** The alsa handle */
  36         snd_pcm_t *handle;
  37         /** Determined and set by alsa_init(). */
  38         int bytes_per_frame;
  39         /** The approximate maximum buffer duration in us. */
  40         unsigned buffer_time;
  41         /* Number of frames that fit into the buffer. */
  42         snd_pcm_uframes_t buffer_frames;
  43         /**
  44          * The sample rate given by command line option or the decoder
  45          * of the writer node group.
  46          */
  47         unsigned sample_rate;
  48         snd_pcm_format_t sample_format;
  49         /**
  50          * The number of channels, given by command line option or the
  51          * decoder of the writer node group.
  52          */
  53         unsigned channels;
  54         struct timeval drain_barrier;
  55         /* File descriptor for select(). */
  56         int poll_fd;
  57 };
  58
  59 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
  60 {
  61         switch (sf) {
  62         case SF_S8: return SND_PCM_FORMAT_S8;
  63         case SF_U8: return SND_PCM_FORMAT_U8;
  64         case SF_S16_LE: return SND_PCM_FORMAT_S16_LE;
  65         case SF_S16_BE: return SND_PCM_FORMAT_S16_BE;
  66         case SF_U16_LE: return SND_PCM_FORMAT_U16_LE;
  67         case SF_U16_BE: return SND_PCM_FORMAT_U16_BE;
  68         default: return SND_PCM_FORMAT_S16_LE;
  69         }
  70 }
  71
  72 /* Install PCM software and hardware configuration. */
  73 static int alsa_init(struct private_alsa_write_data *pad,
  74                 struct alsa_write_args_info *conf)
  75 {
  76         snd_pcm_hw_params_t *hwparams;
  77         snd_pcm_sw_params_t *swparams;
  78         snd_pcm_uframes_t start_threshold, stop_threshold;
  79         snd_pcm_uframes_t period_size;
  80         int err;
  81
  82         PARA_INFO_LOG("opening %s\n", conf->device_arg);
  83         err = snd_pcm_open(&pad->handle, conf->device_arg,
  84                 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
  85         if (err < 0)
  86                 return -E_PCM_OPEN;
  87
  88         snd_pcm_hw_params_alloca(&hwparams);
  89         snd_pcm_sw_params_alloca(&swparams);
  90         if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
  91                 return -E_BROKEN_CONF;
  92         if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
  93                         SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
  94                 return -E_ACCESS_TYPE;
  95         if (snd_pcm_hw_params_set_format(pad->handle, hwparams,
  96                         pad->sample_format) < 0)
  97                 return -E_SAMPLE_FORMAT;
  98         if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
  99                         pad->channels) < 0)
 100                 return -E_CHANNEL_COUNT;
 101         if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
 102                         &pad->sample_rate, NULL) < 0)
 103                 return -E_SET_RATE;
 104         err = snd_pcm_hw_params_get_buffer_time_max(hwparams,
 105                 &pad->buffer_time, NULL);
 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, NULL) < 0)
 111                 return -E_SET_BUFFER_TIME;
 112         if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
 113                 return -E_HW_PARAMS;
 114         snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
 115         snd_pcm_hw_params_get_buffer_size(hwparams, &pad->buffer_frames);
 116         PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad->buffer_frames,
 117                 period_size);
 118         if (period_size == pad->buffer_frames)
 119                 return -E_BAD_PERIOD;
 120         snd_pcm_sw_params_current(pad->handle, swparams);
 121         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 122         if (pad->buffer_frames < 1)
 123                 start_threshold = 1;
 124         else
 125                 start_threshold = PARA_MIN(pad->buffer_frames,
 126                         (snd_pcm_uframes_t)pad->sample_rate);
 127         if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 128                         start_threshold) < 0)
 129                 return -E_START_THRESHOLD;
 130         stop_threshold = pad->buffer_frames;
 131         if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 132                         stop_threshold) < 0)
 133                 return -E_STOP_THRESHOLD;
 134         if (snd_pcm_sw_params(pad->handle, swparams) < 0)
 135                 PARA_WARNING_LOG("unable to install sw params\n");
 136         pad->bytes_per_frame = snd_pcm_format_physical_width(pad->sample_format)
 137                 * pad->channels / 8;
 138         if (pad->bytes_per_frame <= 0)
 139                 return -E_PHYSICAL_WIDTH;
 140         PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
 141         if (snd_pcm_nonblock(pad->handle, 1))
 142                 PARA_ERROR_LOG("failed to set nonblock mode\n");
 143         return 1;
 144 }
 145
 146 static void alsa_write_pre_select(struct sched *s, struct task *t)
 147 {
 148         struct pollfd pfd;
 149         struct writer_node *wn = container_of(t, struct writer_node, task);
 150         struct private_alsa_write_data *pad = wn->private_data;
 151         int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 152
 153         if (pad)
 154                 pad->poll_fd = -1;
 155         if (ret == 0)
 156                 return;
 157         if (!pad) {
 158                 sched_min_delay(s);
 159                 return;
 160         }
 161         if (ret < 0) {
 162                 sched_request_barrier_or_min_delay(&pad->drain_barrier, s);
 163                 return;
 164         }
 165         ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1);
 166         if (ret < 0) {
 167                 PARA_ERROR_LOG("%s\n", snd_strerror(-ret));
 168                 t->error = -E_ALSA_POLL_FDS;
 169                 return;
 170         }
 171         pad->poll_fd = pfd.fd;
 172         para_fd_set(pfd.fd, &s->rfds, &s->max_fileno);
 173 }
 174
 175 static void alsa_close(struct writer_node *wn)
 176 {
 177         struct private_alsa_write_data *pad = wn->private_data;
 178         PARA_INFO_LOG("closing writer node %p\n", wn);
 179
 180         if (!pad)
 181                 return;
 182         /*
 183          * It's OK to have a blocking operation here because we already made
 184          * sure that the PCM output buffer is (nearly) empty.
 185          */
 186         snd_pcm_nonblock(pad->handle, 0);
 187         snd_pcm_drain(pad->handle);
 188         snd_pcm_close(pad->handle);
 189         snd_config_update_free_global();
 190         free(pad);
 191 }
 192
 193 static void alsa_write_post_select(__a_unused struct sched *s,
 194                 struct task *t)
 195 {
 196         struct writer_node *wn = container_of(t, struct writer_node, task);
 197         struct private_alsa_write_data *pad = wn->private_data;
 198         struct btr_node *btrn = wn->btrn;
 199         char *data;
 200         size_t bytes;
 201         snd_pcm_sframes_t frames;
 202         int ret;
 203
 204 again:
 205         t->error = 0;
 206         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 207         if (ret == 0)
 208                 return;
 209         btr_merge(btrn, wn->min_iqs);
 210         bytes = btr_next_buffer(btrn, &data);
 211         if (ret < 0 || bytes < wn->min_iqs) { /* eof */
 212                 assert(btr_no_parent(btrn));
 213                 ret = -E_WRITE_COMMON_EOF;
 214                 if (!pad)
 215                         goto err;
 216                 /* wait until pending frames are played */
 217                 if (pad->drain_barrier.tv_sec == 0) {
 218                         PARA_DEBUG_LOG("waiting for device to drain\n");
 219                         tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
 220                                 &pad->drain_barrier);
 221                         return;
 222                 }
 223                 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
 224                         goto err;
 225                 return;
 226         }
 227         if (!pad) {
 228                 int32_t val;
 229
 230                 if (bytes == 0) /* no data available */
 231                         return;
 232                 pad = para_calloc(sizeof(*pad));
 233                 get_btr_sample_rate(btrn, &val);
 234                 pad->sample_rate = val;
 235                 get_btr_channels(btrn, &val);
 236                 pad->channels = val;
 237                 get_btr_sample_format(btrn, &val);
 238                 pad->sample_format = get_alsa_pcm_format(val);
 239
 240                 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
 241                         pad->sample_rate);
 242                 ret = alsa_init(pad, wn->conf);
 243                 if (ret < 0) {
 244                         free(pad);
 245                         goto err;
 246                 }
 247                 wn->private_data = pad;
 248                 wn->min_iqs = pad->bytes_per_frame;
 249                 goto again;
 250         }
 251         if (pad->poll_fd < 0 || !FD_ISSET(pad->poll_fd, &s->rfds))
 252                 return;
 253         frames = bytes / pad->bytes_per_frame;
 254         frames = snd_pcm_writei(pad->handle, data, frames);
 255         if (frames == 0 || frames == -EAGAIN) {
 256                 /*
 257                  * The alsa poll fd was ready for IO but we failed to write to
 258                  * the alsa handle. This means another event is pending. We
 259                  * don't care about that but we have to dispatch the event in
 260                  * order to avoid a busy loop. So we simply read from the poll
 261                  * fd.
 262                  */
 263                 char buf[100];
 264                 if (read(pad->poll_fd, buf, 100))
 265                         do_nothing;
 266                 return;
 267         }
 268         if (frames > 0) {
 269                 btr_consume(btrn, frames * pad->bytes_per_frame);
 270                 goto again;
 271         }
 272         if (frames == -EPIPE) {
 273                 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
 274                 snd_pcm_prepare(pad->handle);
 275                 return;
 276         }
 277         PARA_WARNING_LOG("%s\n", snd_strerror(-frames));
 278         ret = -E_ALSA_WRITE;
 279 err:
 280         assert(ret < 0);
 281         btr_remove_node(btrn);
 282         t->error = ret;
 283 }
 284
 285 __malloc static void *alsa_parse_config_or_die(const char *options)
 286 {
 287         struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
 288
 289         /* exits on errors */
 290         alsa_cmdline_parser_string(options, conf, "alsa_write");
 291         return conf;
 292 }
 293
 294 static void alsa_free_config(void *conf)
 295 {
 296         alsa_cmdline_parser_free(conf);
 297 }
 298
 299 /**
 300  * The init function of the alsa writer.
 301  *
 302  * \param w Pointer to the writer to initialize.
 303  *
 304  * \sa struct \ref writer.
 305  */
 306 void alsa_write_init(struct writer *w)
 307 {
 308         struct alsa_write_args_info dummy;
 309
 310         alsa_cmdline_parser_init(&dummy);
 311         w->close = alsa_close;
 312         w->pre_select = alsa_write_pre_select;
 313         w->post_select = alsa_write_post_select;
 314         w->parse_config_or_die = alsa_parse_config_or_die;
 315         w->shutdown = NULL; /* nothing to do */
 316         w->free_config = alsa_free_config;
 317         w->help = (struct ggo_help) {
 318                 .short_help = alsa_write_args_info_help,
 319                 .detailed_help = alsa_write_args_info_detailed_help
 320         };
 321         alsa_cmdline_parser_free(&dummy);
 322 }