alsa_write.c

   1 /*
   2  * Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>
   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
  19 #include "para.h"
  20 #include "fd.h"
  21 #include "string.h"
  22 #include "list.h"
  23 #include "sched.h"
  24 #include "ggo.h"
  25 #include "buffer_tree.h"
  26 #include "write.h"
  27 #include "write_common.h"
  28 #include "alsa_write.cmdline.h"
  29 #include "error.h"
  30
  31 /** Data specific to the alsa writer. */
  32 struct private_alsa_write_data {
  33         /** The alsa handle */
  34         snd_pcm_t *handle;
  35         /** Determined and set by alsa_init(). */
  36         int bytes_per_frame;
  37         /*
  38          * If the sample rate is not given at the command line and no wav
  39          * header was detected, the btr exec mechanism is employed to query the
  40          * ancestor buffer tree nodes for this information. In a typical setup
  41          * the decoder passes the sample rate back to the alsa writer.
  42          *
  43          *  \sa \ref btr_exec_up().
  44          */
  45         unsigned sample_rate;
  46         /*
  47          * The sample format (8/16 bit, signed/unsigned, little/big endian) is
  48          * determined in the same way as the \a sample_rate.
  49          */
  50         snd_pcm_format_t sample_format;
  51         /* The number of channels, again determined like \a sample_rate. */
  52         unsigned channels;
  53         /* time until buffer underrun occurs, in milliseconds */
  54         unsigned buffer_time;
  55         struct timeval drain_barrier;
  56         /* File descriptor for select(). */
  57         int poll_fd;
  58 };
  59
  60 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
  61 {
  62         switch (sf) {
  63         case SF_S8: return SND_PCM_FORMAT_S8;
  64         case SF_U8: return SND_PCM_FORMAT_U8;
  65         case SF_S16_LE: return SND_PCM_FORMAT_S16_LE;
  66         case SF_S16_BE: return SND_PCM_FORMAT_S16_BE;
  67         case SF_U16_LE: return SND_PCM_FORMAT_U16_LE;
  68         case SF_U16_BE: return SND_PCM_FORMAT_U16_BE;
  69         default: return SND_PCM_FORMAT_S16_LE;
  70         }
  71 }
  72
  73 /* Install PCM software and hardware configuration. */
  74 static int alsa_init(struct private_alsa_write_data *pad,
  75                 struct alsa_write_args_info *conf)
  76 {
  77         snd_pcm_hw_params_t *hwparams;
  78         snd_pcm_sw_params_t *swparams;
  79         snd_pcm_uframes_t start_threshold, stop_threshold;
  80         snd_pcm_uframes_t buffer_size, period_size;
  81         snd_output_t *output_log;
  82         int ret;
  83         const char *msg;
  84         unsigned period_time;
  85
  86         PARA_INFO_LOG("opening %s\n", conf->device_arg);
  87         msg = "unable to open pcm";
  88         ret = snd_pcm_open(&pad->handle, conf->device_arg,
  89                 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
  90         if (ret < 0)
  91                 goto fail;
  92         snd_pcm_hw_params_alloca(&hwparams);
  93         msg = "Broken alsa configuration";
  94         ret = snd_pcm_hw_params_any(pad->handle, hwparams);
  95         if (ret < 0)
  96                 goto fail;
  97         msg = "access type not available";
  98         ret = snd_pcm_hw_params_set_access(pad->handle, hwparams,
  99                 SND_PCM_ACCESS_RW_INTERLEAVED);
 100         if (ret < 0)
 101                 goto fail;
 102         msg = "sample format not available";
 103         ret = snd_pcm_hw_params_set_format(pad->handle, hwparams,
 104                 pad->sample_format);
 105         if (ret < 0)
 106                 goto fail;
 107         msg = "channels count not available";
 108         ret = snd_pcm_hw_params_set_channels(pad->handle, hwparams,
 109                 pad->channels);
 110         if (ret < 0)
 111                 goto fail;
 112         msg = "could not set sample rate";
 113         ret = snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
 114                 &pad->sample_rate, NULL);
 115         if (ret < 0)
 116                 goto fail;
 117         /* alsa wants microseconds */
 118         pad->buffer_time = conf->buffer_time_arg * 1000;
 119         msg = "could not set buffer time";
 120         ret = snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
 121                 &pad->buffer_time, NULL);
 122         if (ret < 0)
 123                 goto fail;
 124         pad->buffer_time /= 1000; /* we prefer milliseconds */
 125         period_time = pad->buffer_time * 250; /* buffer time / 4 */
 126         msg = "could not set period time";
 127         ret = snd_pcm_hw_params_set_period_time_near(pad->handle, hwparams,
 128                 &period_time, NULL);
 129         if (ret < 0)
 130                 goto fail;
 131
 132         msg = "unable to install hw params";
 133         ret = snd_pcm_hw_params(pad->handle, hwparams);
 134         if (ret < 0)
 135                 goto fail;
 136         snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
 137         snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
 138         msg = "period size equals buffer size";
 139         if (period_size == buffer_size)
 140                 goto fail;
 141
 142         /* software parameter setup */
 143         snd_pcm_sw_params_alloca(&swparams);
 144         snd_pcm_sw_params_current(pad->handle, swparams);
 145         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 146         if (buffer_size < 1)
 147                 start_threshold = 1;
 148         else
 149                 start_threshold = PARA_MIN(buffer_size,
 150                         (snd_pcm_uframes_t)pad->sample_rate);
 151         msg = "could not set start threshold";
 152         ret = snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 153                 start_threshold);
 154         if (ret < 0)
 155                 goto fail;
 156         stop_threshold = buffer_size;
 157         msg = "could not set stop threshold";
 158         ret = snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 159                 stop_threshold);
 160         if (ret < 0)
 161                 goto fail;
 162         msg = "unable to install sw params";
 163         ret = snd_pcm_sw_params(pad->handle, swparams);
 164         if (ret < 0)
 165                 goto fail;
 166         msg = "unable to determine bytes per frame";
 167         ret = snd_pcm_format_physical_width(pad->sample_format);
 168         if (ret <= 0)
 169                 goto fail;
 170         pad->bytes_per_frame = ret * pad->channels / 8;
 171         msg = "failed to set alsa handle to nonblock mode";
 172         ret = snd_pcm_nonblock(pad->handle, 1);
 173         if (ret < 0)
 174                 goto fail;
 175         ret = snd_output_buffer_open(&output_log);
 176         if (ret == 0) {
 177                 char *buf, *p;
 178                 size_t sz;
 179                 PARA_DEBUG_LOG("dumping alsa configuration\n");
 180                 snd_pcm_dump(pad->handle, output_log);
 181                 snd_pcm_hw_params_dump(hwparams, output_log);
 182                 sz = snd_output_buffer_string(output_log, &buf);
 183                 for (p = buf; p < buf + sz;) {
 184                         char *q = memchr(p, '\n', buf + sz - p);
 185                         if (!q)
 186                                 break;
 187                         *q = '\0';
 188                         PARA_DEBUG_LOG("%s\n", p);
 189                         p = q + 1;
 190                 }
 191                 snd_output_close(output_log);
 192         }
 193         return 1;
 194 fail:
 195         if (ret < 0)
 196                 PARA_ERROR_LOG("%s: %s\n", msg, snd_strerror(-ret));
 197         else
 198                 PARA_ERROR_LOG("%s\n", msg);
 199         return -E_ALSA;
 200 }
 201
 202 static void alsa_write_pre_select(struct sched *s, void *context)
 203 {
 204         struct pollfd pfd;
 205         struct writer_node *wn = context;
 206         struct private_alsa_write_data *pad = wn->private_data;
 207         int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 208
 209         if (pad)
 210                 pad->poll_fd = -1;
 211         if (ret == 0)
 212                 return;
 213         if (!pad) {
 214                 sched_min_delay(s);
 215                 return;
 216         }
 217         if (ret < 0) {
 218                 sched_request_barrier_or_min_delay(&pad->drain_barrier, s);
 219                 return;
 220         }
 221         /* wait at most 50% of the buffer time */
 222         sched_request_timeout_ms(pad->buffer_time / 2, s);
 223         ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1);
 224         if (ret < 0) {
 225                 PARA_ERROR_LOG("could not get alsa poll fd: %s\n",
 226                         snd_strerror(-ret));
 227                 return;
 228         }
 229         pad->poll_fd = pfd.fd;
 230         para_fd_set(pfd.fd, &s->rfds, &s->max_fileno);
 231 }
 232
 233 static void alsa_close(struct writer_node *wn)
 234 {
 235         struct private_alsa_write_data *pad = wn->private_data;
 236         PARA_INFO_LOG("closing writer node %p\n", wn);
 237
 238         if (!pad)
 239                 return;
 240         /*
 241          * It's OK to have a blocking operation here because we already made
 242          * sure that the PCM output buffer is (nearly) empty.
 243          */
 244         snd_pcm_nonblock(pad->handle, 0);
 245         snd_pcm_drain(pad->handle);
 246         snd_pcm_close(pad->handle);
 247         snd_config_update_free_global();
 248         free(pad);
 249 }
 250
 251 static int alsa_write_post_select(__a_unused struct sched *s, void *context)
 252 {
 253         struct writer_node *wn = context;
 254         struct private_alsa_write_data *pad = wn->private_data;
 255         struct btr_node *btrn = wn->btrn;
 256         char *data;
 257         size_t bytes;
 258         snd_pcm_sframes_t frames;
 259         int ret;
 260
 261         ret = task_get_notification(wn->task);
 262         if (ret < 0)
 263                 goto err;
 264 again:
 265         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 266         if (ret == 0)
 267                 return 0;
 268         btr_merge(btrn, wn->min_iqs);
 269         bytes = btr_next_buffer(btrn, &data);
 270         if (ret < 0 || bytes < wn->min_iqs) { /* eof */
 271                 assert(btr_no_parent(btrn));
 272                 ret = -E_WRITE_COMMON_EOF;
 273                 if (!pad)
 274                         goto err;
 275                 /* wait until pending frames are played */
 276                 if (pad->drain_barrier.tv_sec == 0) {
 277                         PARA_DEBUG_LOG("waiting for device to drain\n");
 278                         tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
 279                                 &pad->drain_barrier);
 280                         return 0;
 281                 }
 282                 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
 283                         goto err;
 284                 return 0;
 285         }
 286         if (!pad) {
 287                 int32_t val;
 288
 289                 if (bytes == 0) /* no data available */
 290                         return 0;
 291                 pad = para_calloc(sizeof(*pad));
 292                 get_btr_sample_rate(btrn, &val);
 293                 pad->sample_rate = val;
 294                 get_btr_channels(btrn, &val);
 295                 pad->channels = val;
 296                 get_btr_sample_format(btrn, &val);
 297                 pad->sample_format = get_alsa_pcm_format(val);
 298
 299                 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
 300                         pad->sample_rate);
 301                 ret = alsa_init(pad, wn->conf);
 302                 if (ret < 0) {
 303                         free(pad);
 304                         goto err;
 305                 }
 306                 wn->private_data = pad;
 307                 wn->min_iqs = pad->bytes_per_frame;
 308                 goto again;
 309         }
 310         frames = bytes / pad->bytes_per_frame;
 311         frames = snd_pcm_writei(pad->handle, data, frames);
 312         if (frames == 0 || frames == -EAGAIN) {
 313                 char buf[100];
 314                 if (pad->poll_fd >= 0 && FD_ISSET(pad->poll_fd, &s->rfds))
 315                         if (read(pad->poll_fd, buf, 100))
 316                                 do_nothing;
 317                 return 0;
 318         }
 319         if (frames > 0) {
 320                 btr_consume(btrn, frames * pad->bytes_per_frame);
 321                 goto again;
 322         }
 323         if (frames == -EPIPE) {
 324                 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
 325                 snd_pcm_prepare(pad->handle);
 326                 return 0;
 327         }
 328         PARA_ERROR_LOG("alsa write error: %s\n", snd_strerror(-frames));
 329         ret = -E_ALSA;
 330 err:
 331         assert(ret < 0);
 332         btr_remove_node(&wn->btrn);
 333         return ret;
 334 }
 335
 336 __malloc static void *alsa_parse_config_or_die(int argc, char **argv)
 337 {
 338         struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
 339
 340         /* exits on errors */
 341         alsa_write_cmdline_parser(argc, argv, conf);
 342         return conf;
 343 }
 344
 345 static void alsa_free_config(void *conf)
 346 {
 347         alsa_write_cmdline_parser_free(conf);
 348 }
 349
 350 /**
 351  * The init function of the alsa writer.
 352  *
 353  * \param w Pointer to the writer to initialize.
 354  *
 355  * \sa struct \ref writer.
 356  */
 357 void alsa_write_init(struct writer *w)
 358 {
 359         struct alsa_write_args_info dummy;
 360
 361         alsa_write_cmdline_parser_init(&dummy);
 362         w->close = alsa_close;
 363         w->pre_select = alsa_write_pre_select;
 364         w->post_select = alsa_write_post_select;
 365         w->parse_config_or_die = alsa_parse_config_or_die;
 366         w->free_config = alsa_free_config;
 367         w->help = (struct ggo_help)DEFINE_GGO_HELP(alsa_write);
 368         alsa_write_cmdline_parser_free(&dummy);
 369 }