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
  20 #include "para.h"
  21 #include "fd.h"
  22 #include "string.h"
  23 #include "list.h"
  24 #include "sched.h"
  25 #include "ggo.h"
  26 #include "buffer_tree.h"
  27 #include "write.h"
  28 #include "write_common.h"
  29 #include "alsa_write.cmdline.h"
  30 #include "error.h"
  31
  32 /** Data specific to the alsa writer. */
  33 struct private_alsa_write_data {
  34         /** The alsa handle */
  35         snd_pcm_t *handle;
  36         /** Determined and set by alsa_init(). */
  37         int bytes_per_frame;
  38         /**
  39          * The sample rate given by command line option or the decoder
  40          * of the writer node group.
  41          */
  42         unsigned sample_rate;
  43         snd_pcm_format_t sample_format;
  44         /**
  45          * The number of channels, given by command line option or the
  46          * decoder of the writer node group.
  47          */
  48         unsigned channels;
  49         struct timeval drain_barrier;
  50         /* File descriptor for select(). */
  51         int poll_fd;
  52 };
  53
  54 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
  55 {
  56         switch (sf) {
  57         case SF_S8: return SND_PCM_FORMAT_S8;
  58         case SF_U8: return SND_PCM_FORMAT_U8;
  59         case SF_S16_LE: return SND_PCM_FORMAT_S16_LE;
  60         case SF_S16_BE: return SND_PCM_FORMAT_S16_BE;
  61         case SF_U16_LE: return SND_PCM_FORMAT_U16_LE;
  62         case SF_U16_BE: return SND_PCM_FORMAT_U16_BE;
  63         default: return SND_PCM_FORMAT_S16_LE;
  64         }
  65 }
  66
  67 /* Install PCM software and hardware configuration. */
  68 static int alsa_init(struct private_alsa_write_data *pad,
  69                 struct alsa_write_args_info *conf)
  70 {
  71         snd_pcm_hw_params_t *hwparams;
  72         snd_pcm_sw_params_t *swparams;
  73         snd_pcm_uframes_t start_threshold, stop_threshold;
  74         snd_pcm_uframes_t buffer_size, period_size;
  75         snd_output_t *log;
  76         unsigned buffer_time;
  77         int ret;
  78         const char *msg;
  79
  80         PARA_INFO_LOG("opening %s\n", conf->device_arg);
  81         msg = "unable to open pcm";
  82         ret = snd_pcm_open(&pad->handle, conf->device_arg,
  83                 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
  84         if (ret < 0)
  85                 goto fail;
  86         snd_pcm_hw_params_alloca(&hwparams);
  87         msg = "Broken alsa configuration";
  88         ret = snd_pcm_hw_params_any(pad->handle, hwparams);
  89         if (ret < 0)
  90                 goto fail;
  91         msg = "access type not available";
  92         ret = snd_pcm_hw_params_set_access(pad->handle, hwparams,
  93                 SND_PCM_ACCESS_RW_INTERLEAVED);
  94         if (ret < 0)
  95                 goto fail;
  96         msg = "sample format not available";
  97         ret = snd_pcm_hw_params_set_format(pad->handle, hwparams,
  98                 pad->sample_format);
  99         if (ret < 0)
 100                 goto fail;
 101         msg = "channels count not available";
 102         ret = snd_pcm_hw_params_set_channels(pad->handle, hwparams,
 103                 pad->channels);
 104         if (ret < 0)
 105                 goto fail;
 106         msg = "could not set sample rate";
 107         ret = snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
 108                 &pad->sample_rate, NULL);
 109         if (ret < 0)
 110                 goto fail;
 111         msg = "unable to get buffer time";
 112         ret = snd_pcm_hw_params_get_buffer_time_max(hwparams, &buffer_time,
 113                 NULL);
 114         if (ret < 0 || buffer_time == 0)
 115                 goto fail;
 116         msg = "could not set buffer time";
 117         ret = snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
 118                 &buffer_time, NULL);
 119         if (ret < 0)
 120                 goto fail;
 121         msg = "unable to install hw params";
 122         ret = snd_pcm_hw_params(pad->handle, hwparams);
 123         if (ret < 0)
 124                 goto fail;
 125         snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
 126         snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
 127         msg = "period size equals buffer size";
 128         if (period_size == buffer_size)
 129                 goto fail;
 130
 131         /* software parameter setup */
 132         snd_pcm_sw_params_alloca(&swparams);
 133         snd_pcm_sw_params_current(pad->handle, swparams);
 134         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 135         if (buffer_size < 1)
 136                 start_threshold = 1;
 137         else
 138                 start_threshold = PARA_MIN(buffer_size,
 139                         (snd_pcm_uframes_t)pad->sample_rate);
 140         msg = "could not set start threshold";
 141         ret = snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 142                 start_threshold);
 143         if (ret < 0)
 144                 goto fail;
 145         stop_threshold = buffer_size;
 146         msg = "could not set stop threshold";
 147         ret = snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 148                 stop_threshold);
 149         if (ret < 0)
 150                 goto fail;
 151         msg = "unable to install sw params";
 152         ret = snd_pcm_sw_params(pad->handle, swparams);
 153         if (ret < 0)
 154                 goto fail;
 155         msg = "unable to determine bytes per frame";
 156         ret = snd_pcm_format_physical_width(pad->sample_format);
 157         if (ret <= 0)
 158                 goto fail;
 159         pad->bytes_per_frame = ret * pad->channels / 8;
 160         msg = "failed to set alsa handle to nonblock mode";
 161         ret = snd_pcm_nonblock(pad->handle, 1);
 162         if (ret < 0)
 163                 goto fail;
 164         ret = snd_output_buffer_open(&log);
 165         if (ret == 0) {
 166                 char *buf;
 167                 PARA_INFO_LOG("dumping alsa configuration\n");
 168                 snd_pcm_dump(pad->handle, log);
 169                 snd_output_buffer_string(log, &buf);
 170                 for (;;) {
 171                         char *p = strchr(buf, '\n');
 172                         if (!p) /* omit last output line, it's empty */
 173                                 break;
 174                         *p = '\0';
 175                         PARA_INFO_LOG("%s\n", buf);
 176                         buf = p + 1;
 177                 }
 178                 snd_output_close(log);
 179         }
 180         return 1;
 181 fail:
 182         if (ret < 0)
 183                 PARA_ERROR_LOG("%s: %s\n", msg, snd_strerror(-ret));
 184         else
 185                 PARA_ERROR_LOG("%s\n", msg);
 186         return -E_ALSA;
 187 }
 188
 189 static void alsa_write_pre_select(struct sched *s, struct task *t)
 190 {
 191         struct pollfd pfd;
 192         struct writer_node *wn = container_of(t, struct writer_node, task);
 193         struct private_alsa_write_data *pad = wn->private_data;
 194         int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 195
 196         if (pad)
 197                 pad->poll_fd = -1;
 198         if (ret == 0)
 199                 return;
 200         if (!pad) {
 201                 sched_min_delay(s);
 202                 return;
 203         }
 204         if (ret < 0) {
 205                 sched_request_barrier_or_min_delay(&pad->drain_barrier, s);
 206                 return;
 207         }
 208         ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1);
 209         if (ret < 0) {
 210                 PARA_ERROR_LOG("could not get alsa poll fd: %s\n",
 211                         snd_strerror(-ret));
 212                 t->error = -E_ALSA;
 213                 return;
 214         }
 215         pad->poll_fd = pfd.fd;
 216         para_fd_set(pfd.fd, &s->rfds, &s->max_fileno);
 217 }
 218
 219 static void alsa_close(struct writer_node *wn)
 220 {
 221         struct private_alsa_write_data *pad = wn->private_data;
 222         PARA_INFO_LOG("closing writer node %p\n", wn);
 223
 224         if (!pad)
 225                 return;
 226         /*
 227          * It's OK to have a blocking operation here because we already made
 228          * sure that the PCM output buffer is (nearly) empty.
 229          */
 230         snd_pcm_nonblock(pad->handle, 0);
 231         snd_pcm_drain(pad->handle);
 232         snd_pcm_close(pad->handle);
 233         snd_config_update_free_global();
 234         free(pad);
 235 }
 236
 237 static void alsa_write_post_select(__a_unused struct sched *s,
 238                 struct task *t)
 239 {
 240         struct writer_node *wn = container_of(t, struct writer_node, task);
 241         struct private_alsa_write_data *pad = wn->private_data;
 242         struct btr_node *btrn = wn->btrn;
 243         char *data;
 244         size_t bytes;
 245         snd_pcm_sframes_t frames;
 246         int ret;
 247
 248 again:
 249         t->error = 0;
 250         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 251         if (ret == 0)
 252                 return;
 253         btr_merge(btrn, wn->min_iqs);
 254         bytes = btr_next_buffer(btrn, &data);
 255         if (ret < 0 || bytes < wn->min_iqs) { /* eof */
 256                 assert(btr_no_parent(btrn));
 257                 ret = -E_WRITE_COMMON_EOF;
 258                 if (!pad)
 259                         goto err;
 260                 /* wait until pending frames are played */
 261                 if (pad->drain_barrier.tv_sec == 0) {
 262                         PARA_DEBUG_LOG("waiting for device to drain\n");
 263                         tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
 264                                 &pad->drain_barrier);
 265                         return;
 266                 }
 267                 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
 268                         goto err;
 269                 return;
 270         }
 271         if (!pad) {
 272                 int32_t val;
 273
 274                 if (bytes == 0) /* no data available */
 275                         return;
 276                 pad = para_calloc(sizeof(*pad));
 277                 get_btr_sample_rate(btrn, &val);
 278                 pad->sample_rate = val;
 279                 get_btr_channels(btrn, &val);
 280                 pad->channels = val;
 281                 get_btr_sample_format(btrn, &val);
 282                 pad->sample_format = get_alsa_pcm_format(val);
 283
 284                 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
 285                         pad->sample_rate);
 286                 ret = alsa_init(pad, wn->conf);
 287                 if (ret < 0) {
 288                         free(pad);
 289                         goto err;
 290                 }
 291                 wn->private_data = pad;
 292                 wn->min_iqs = pad->bytes_per_frame;
 293                 goto again;
 294         }
 295         if (pad->poll_fd < 0 || !FD_ISSET(pad->poll_fd, &s->rfds))
 296                 return;
 297         frames = bytes / pad->bytes_per_frame;
 298         frames = snd_pcm_writei(pad->handle, data, frames);
 299         if (frames == 0 || frames == -EAGAIN) {
 300                 /*
 301                  * The alsa poll fd was ready for IO but we failed to write to
 302                  * the alsa handle. This means another event is pending. We
 303                  * don't care about that but we have to dispatch the event in
 304                  * order to avoid a busy loop. So we simply read from the poll
 305                  * fd.
 306                  */
 307                 char buf[100];
 308                 if (read(pad->poll_fd, buf, 100))
 309                         do_nothing;
 310                 return;
 311         }
 312         if (frames > 0) {
 313                 btr_consume(btrn, frames * pad->bytes_per_frame);
 314                 goto again;
 315         }
 316         if (frames == -EPIPE) {
 317                 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
 318                 snd_pcm_prepare(pad->handle);
 319                 return;
 320         }
 321         PARA_ERROR_LOG("alsa write error: %s\n", snd_strerror(-frames));
 322         ret = -E_ALSA;
 323 err:
 324         assert(ret < 0);
 325         btr_remove_node(btrn);
 326         t->error = ret;
 327 }
 328
 329 __malloc static void *alsa_parse_config_or_die(const char *options)
 330 {
 331         struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
 332
 333         /* exits on errors */
 334         alsa_cmdline_parser_string(options, conf, "alsa_write");
 335         return conf;
 336 }
 337
 338 static void alsa_free_config(void *conf)
 339 {
 340         alsa_cmdline_parser_free(conf);
 341 }
 342
 343 /**
 344  * The init function of the alsa writer.
 345  *
 346  * \param w Pointer to the writer to initialize.
 347  *
 348  * \sa struct \ref writer.
 349  */
 350 void alsa_write_init(struct writer *w)
 351 {
 352         struct alsa_write_args_info dummy;
 353
 354         alsa_cmdline_parser_init(&dummy);
 355         w->close = alsa_close;
 356         w->pre_select = alsa_write_pre_select;
 357         w->post_select = alsa_write_post_select;
 358         w->parse_config_or_die = alsa_parse_config_or_die;
 359         w->shutdown = NULL; /* nothing to do */
 360         w->free_config = alsa_free_config;
 361         w->help = (struct ggo_help) {
 362                 .short_help = alsa_write_args_info_help,
 363                 .detailed_help = alsa_write_args_info_detailed_help
 364         };
 365         alsa_cmdline_parser_free(&dummy);
 366 }