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         /**
  40          * The sample rate given by command line option or the decoder
  41          * of the writer node group.
  42          */
  43         unsigned sample_rate;
  44         snd_pcm_format_t sample_format;
  45         /**
  46          * The number of channels, given by command line option or the
  47          * decoder of the writer node group.
  48          */
  49         unsigned channels;
  50         struct timeval drain_barrier;
  51         /* File descriptor for select(). */
  52         int poll_fd;
  53 };
  54
  55 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
  56 {
  57         switch (sf) {
  58         case SF_S8: return SND_PCM_FORMAT_S8;
  59         case SF_U8: return SND_PCM_FORMAT_U8;
  60         case SF_S16_LE: return SND_PCM_FORMAT_S16_LE;
  61         case SF_S16_BE: return SND_PCM_FORMAT_S16_BE;
  62         case SF_U16_LE: return SND_PCM_FORMAT_U16_LE;
  63         case SF_U16_BE: return SND_PCM_FORMAT_U16_BE;
  64         default: return SND_PCM_FORMAT_S16_LE;
  65         }
  66 }
  67
  68 /* Install PCM software and hardware configuration. */
  69 static int alsa_init(struct private_alsa_write_data *pad,
  70                 struct alsa_write_args_info *conf)
  71 {
  72         snd_pcm_hw_params_t *hwparams;
  73         snd_pcm_sw_params_t *swparams;
  74         snd_pcm_uframes_t start_threshold, stop_threshold;
  75         snd_pcm_uframes_t buffer_size, period_size;
  76         snd_output_t *log;
  77         unsigned buffer_time;
  78         int ret;
  79         const char *msg;
  80
  81         PARA_INFO_LOG("opening %s\n", conf->device_arg);
  82         msg = "unable to open pcm";
  83         ret = snd_pcm_open(&pad->handle, conf->device_arg,
  84                 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
  85         if (ret < 0)
  86                 goto fail;
  87         snd_pcm_hw_params_alloca(&hwparams);
  88         msg = "Broken alsa configuration";
  89         ret = snd_pcm_hw_params_any(pad->handle, hwparams);
  90         if (ret < 0)
  91                 goto fail;
  92         msg = "access type not available";
  93         ret = snd_pcm_hw_params_set_access(pad->handle, hwparams,
  94                 SND_PCM_ACCESS_RW_INTERLEAVED);
  95         if (ret < 0)
  96                 goto fail;
  97         msg = "sample format not available";
  98         ret = snd_pcm_hw_params_set_format(pad->handle, hwparams,
  99                 pad->sample_format);
 100         if (ret < 0)
 101                 goto fail;
 102         msg = "channels count not available";
 103         ret = snd_pcm_hw_params_set_channels(pad->handle, hwparams,
 104                 pad->channels);
 105         if (ret < 0)
 106                 goto fail;
 107         msg = "could not set sample rate";
 108         ret = snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
 109                 &pad->sample_rate, NULL);
 110         if (ret < 0)
 111                 goto fail;
 112         msg = "unable to get buffer time";
 113         ret = snd_pcm_hw_params_get_buffer_time_max(hwparams, &buffer_time,
 114                 NULL);
 115         if (ret < 0 || buffer_time == 0)
 116                 goto fail;
 117         msg = "could not set buffer time";
 118         ret = snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
 119                 &buffer_time, NULL);
 120         if (ret < 0)
 121                 goto fail;
 122         msg = "unable to install hw params";
 123         ret = snd_pcm_hw_params(pad->handle, hwparams);
 124         if (ret < 0)
 125                 goto fail;
 126         snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
 127         snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
 128         msg = "period size equals buffer size";
 129         if (period_size == buffer_size)
 130                 goto fail;
 131
 132         /* software parameter setup */
 133         snd_pcm_sw_params_alloca(&swparams);
 134         snd_pcm_sw_params_current(pad->handle, swparams);
 135         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 136         if (buffer_size < 1)
 137                 start_threshold = 1;
 138         else
 139                 start_threshold = PARA_MIN(buffer_size,
 140                         (snd_pcm_uframes_t)pad->sample_rate);
 141         msg = "could not set start threshold";
 142         ret = snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 143                 start_threshold);
 144         if (ret < 0)
 145                 goto fail;
 146         stop_threshold = buffer_size;
 147         msg = "could not set stop threshold";
 148         ret = snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 149                 stop_threshold);
 150         if (ret < 0)
 151                 goto fail;
 152         msg = "unable to install sw params";
 153         ret = snd_pcm_sw_params(pad->handle, swparams);
 154         if (ret < 0)
 155                 goto fail;
 156         msg = "unable to determine bytes per frame";
 157         ret = snd_pcm_format_physical_width(pad->sample_format);
 158         if (ret <= 0)
 159                 goto fail;
 160         pad->bytes_per_frame = ret * pad->channels / 8;
 161         msg = "failed to set alsa handle to nonblock mode";
 162         ret = snd_pcm_nonblock(pad->handle, 1);
 163         if (ret < 0)
 164                 goto fail;
 165         ret = snd_output_buffer_open(&log);
 166         if (ret == 0) {
 167                 char *buf;
 168                 PARA_INFO_LOG("dumping alsa configuration\n");
 169                 snd_pcm_dump(pad->handle, log);
 170                 snd_output_buffer_string(log, &buf);
 171                 for (;;) {
 172                         char *p = strchr(buf, '\n');
 173                         if (!p) /* omit last output line, it's empty */
 174                                 break;
 175                         *p = '\0';
 176                         PARA_INFO_LOG("%s\n", buf);
 177                         buf = p + 1;
 178                 }
 179                 snd_output_close(log);
 180         }
 181         return 1;
 182 fail:
 183         if (ret < 0)
 184                 PARA_ERROR_LOG("%s: %s\n", msg, snd_strerror(-ret));
 185         else
 186                 PARA_ERROR_LOG("%s\n", msg);
 187         return -E_ALSA;
 188 }
 189
 190 static void alsa_write_pre_select(struct sched *s, struct task *t)
 191 {
 192         struct pollfd pfd;
 193         struct writer_node *wn = container_of(t, struct writer_node, task);
 194         struct private_alsa_write_data *pad = wn->private_data;
 195         int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 196
 197         if (pad)
 198                 pad->poll_fd = -1;
 199         if (ret == 0)
 200                 return;
 201         if (!pad) {
 202                 sched_min_delay(s);
 203                 return;
 204         }
 205         if (ret < 0) {
 206                 sched_request_barrier_or_min_delay(&pad->drain_barrier, s);
 207                 return;
 208         }
 209         ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1);
 210         if (ret < 0) {
 211                 PARA_ERROR_LOG("could not get alsa poll fd: %s\n",
 212                         snd_strerror(-ret));
 213                 t->error = -E_ALSA;
 214                 return;
 215         }
 216         pad->poll_fd = pfd.fd;
 217         para_fd_set(pfd.fd, &s->rfds, &s->max_fileno);
 218 }
 219
 220 static void alsa_close(struct writer_node *wn)
 221 {
 222         struct private_alsa_write_data *pad = wn->private_data;
 223         PARA_INFO_LOG("closing writer node %p\n", wn);
 224
 225         if (!pad)
 226                 return;
 227         /*
 228          * It's OK to have a blocking operation here because we already made
 229          * sure that the PCM output buffer is (nearly) empty.
 230          */
 231         snd_pcm_nonblock(pad->handle, 0);
 232         snd_pcm_drain(pad->handle);
 233         snd_pcm_close(pad->handle);
 234         snd_config_update_free_global();
 235         free(pad);
 236 }
 237
 238 static void alsa_write_post_select(__a_unused struct sched *s,
 239                 struct task *t)
 240 {
 241         struct writer_node *wn = container_of(t, struct writer_node, task);
 242         struct private_alsa_write_data *pad = wn->private_data;
 243         struct btr_node *btrn = wn->btrn;
 244         char *data;
 245         size_t bytes;
 246         snd_pcm_sframes_t frames;
 247         int ret;
 248
 249 again:
 250         t->error = 0;
 251         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 252         if (ret == 0)
 253                 return;
 254         btr_merge(btrn, wn->min_iqs);
 255         bytes = btr_next_buffer(btrn, &data);
 256         if (ret < 0 || bytes < wn->min_iqs) { /* eof */
 257                 assert(btr_no_parent(btrn));
 258                 ret = -E_WRITE_COMMON_EOF;
 259                 if (!pad)
 260                         goto err;
 261                 /* wait until pending frames are played */
 262                 if (pad->drain_barrier.tv_sec == 0) {
 263                         PARA_DEBUG_LOG("waiting for device to drain\n");
 264                         tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
 265                                 &pad->drain_barrier);
 266                         return;
 267                 }
 268                 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
 269                         goto err;
 270                 return;
 271         }
 272         if (!pad) {
 273                 int32_t val;
 274
 275                 if (bytes == 0) /* no data available */
 276                         return;
 277                 pad = para_calloc(sizeof(*pad));
 278                 get_btr_sample_rate(btrn, &val);
 279                 pad->sample_rate = val;
 280                 get_btr_channels(btrn, &val);
 281                 pad->channels = val;
 282                 get_btr_sample_format(btrn, &val);
 283                 pad->sample_format = get_alsa_pcm_format(val);
 284
 285                 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
 286                         pad->sample_rate);
 287                 ret = alsa_init(pad, wn->conf);
 288                 if (ret < 0) {
 289                         free(pad);
 290                         goto err;
 291                 }
 292                 wn->private_data = pad;
 293                 wn->min_iqs = pad->bytes_per_frame;
 294                 goto again;
 295         }
 296         if (pad->poll_fd < 0 || !FD_ISSET(pad->poll_fd, &s->rfds))
 297                 return;
 298         frames = bytes / pad->bytes_per_frame;
 299         frames = snd_pcm_writei(pad->handle, data, frames);
 300         if (frames == 0 || frames == -EAGAIN) {
 301                 /*
 302                  * The alsa poll fd was ready for IO but we failed to write to
 303                  * the alsa handle. This means another event is pending. We
 304                  * don't care about that but we have to dispatch the event in
 305                  * order to avoid a busy loop. So we simply read from the poll
 306                  * fd.
 307                  */
 308                 char buf[100];
 309                 if (read(pad->poll_fd, buf, 100))
 310                         do_nothing;
 311                 return;
 312         }
 313         if (frames > 0) {
 314                 btr_consume(btrn, frames * pad->bytes_per_frame);
 315                 goto again;
 316         }
 317         if (frames == -EPIPE) {
 318                 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
 319                 snd_pcm_prepare(pad->handle);
 320                 return;
 321         }
 322         PARA_ERROR_LOG("alsa write error: %s\n", snd_strerror(-frames));
 323         ret = -E_ALSA;
 324 err:
 325         assert(ret < 0);
 326         btr_remove_node(btrn);
 327         t->error = ret;
 328 }
 329
 330 __malloc static void *alsa_parse_config_or_die(const char *options)
 331 {
 332         struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
 333
 334         /* exits on errors */
 335         alsa_cmdline_parser_string(options, conf, "alsa_write");
 336         return conf;
 337 }
 338
 339 static void alsa_free_config(void *conf)
 340 {
 341         alsa_cmdline_parser_free(conf);
 342 }
 343
 344 /**
 345  * The init function of the alsa writer.
 346  *
 347  * \param w Pointer to the writer to initialize.
 348  *
 349  * \sa struct \ref writer.
 350  */
 351 void alsa_write_init(struct writer *w)
 352 {
 353         struct alsa_write_args_info dummy;
 354
 355         alsa_cmdline_parser_init(&dummy);
 356         w->close = alsa_close;
 357         w->pre_select = alsa_write_pre_select;
 358         w->post_select = alsa_write_post_select;
 359         w->parse_config_or_die = alsa_parse_config_or_die;
 360         w->shutdown = NULL; /* nothing to do */
 361         w->free_config = alsa_free_config;
 362         w->help = (struct ggo_help) {
 363                 .short_help = alsa_write_args_info_help,
 364                 .detailed_help = alsa_write_args_info_detailed_help
 365         };
 366         alsa_cmdline_parser_free(&dummy);
 367 }