alsa_write.c

   1 /*
   2  * Copyright (C) 2005-2010 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 <dirent.h>
  18 #include <alsa/asoundlib.h>
  19 #include <sys/time.h>
  20 #include <stdbool.h>
  21
  22 #include "para.h"
  23 #include "fd.h"
  24 #include "string.h"
  25 #include "list.h"
  26 #include "sched.h"
  27 #include "ggo.h"
  28 #include "buffer_tree.h"
  29 #include "write.h"
  30 #include "write_common.h"
  31 #include "alsa_write.cmdline.h"
  32 #include "error.h"
  33
  34 /** Data specific to the alsa writer. */
  35 struct private_alsa_write_data {
  36         /** The alsa handle */
  37         snd_pcm_t *handle;
  38         /** Determined and set by alsa_open(). */
  39         int bytes_per_frame;
  40         /** The approximate maximum buffer duration in us. */
  41         unsigned buffer_time;
  42         /* Number of frames that fit into the buffer. */
  43         snd_pcm_uframes_t buffer_frames;
  44         /**
  45          * The sample rate given by command line option or the decoder
  46          * of the writer node group.
  47          */
  48         unsigned sample_rate;
  49
  50         snd_pcm_format_t sample_format;
  51         /**
  52          * The number of channels, given by command line option or the
  53          * decoder of the writer node group.
  54          */
  55         unsigned channels;
  56         struct timeval drain_barrier;
  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 /* Open an instance of the alsa writer. */
 147 static int alsa_open(struct writer_node *wn)
 148 {
 149         wn->private_data = para_calloc(sizeof(struct private_alsa_write_data));
 150         return 1;
 151 }
 152
 153 static void alsa_write_pre_select(struct sched *s, struct task *t)
 154 {
 155         struct writer_node *wn = container_of(t, struct writer_node, task);
 156         struct private_alsa_write_data *pad = wn->private_data;
 157         struct timeval tv;
 158         snd_pcm_sframes_t avail, underrun;
 159         int ret;
 160
 161         if (!pad->handle)
 162                 return;
 163         ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 164         if (ret < 0)
 165                 sched_request_timeout_ms(20, s);
 166         if (ret <= 0)
 167                 return;
 168         /*
 169          * Data is available to be written to the alsa handle.  Compute number
 170          * of milliseconds until next buffer underrun would occur.
 171          *
 172          * snd_pcm_avail_update() updates the current available count of
 173          * samples for writing.  It is a light method to obtain current stream
 174          * position, because it does not require the user <-> kernel context
 175          * switch, but the value is less accurate, because ring buffer pointers
 176          * are updated in kernel drivers only when an interrupt occurs.
 177          */
 178         avail = snd_pcm_avail_update(pad->handle);
 179         if (avail < 0)
 180                 avail = 0;
 181         underrun = (pad->buffer_frames - avail) * pad->buffer_time
 182                 / pad->buffer_frames / 1000;
 183         if (underrun < 50)
 184                 underrun = 50;
 185         underrun -= 50;
 186         ms2tv(underrun, &tv);
 187         if (tv_diff(&s->timeout, &tv, NULL) > 0)
 188                 s->timeout = tv;
 189 }
 190
 191 static void alsa_close(struct writer_node *wn)
 192 {
 193         struct private_alsa_write_data *pad = wn->private_data;
 194         PARA_INFO_LOG("closing writer node %p\n", wn);
 195
 196         if (pad->handle) {
 197                 /*
 198                  * It's OK to have a blocking operation here because we already
 199                  * made sure that the PCM output buffer is (nearly) empty.
 200                  */
 201                 snd_pcm_nonblock(pad->handle, 0);
 202                 snd_pcm_drain(pad->handle);
 203                 snd_pcm_close(pad->handle);
 204                 snd_config_update_free_global();
 205         }
 206         free(pad);
 207 }
 208
 209 static void alsa_write_post_select(__a_unused struct sched *s,
 210                 struct task *t)
 211 {
 212         struct writer_node *wn = container_of(t, struct writer_node, task);
 213         struct private_alsa_write_data *pad = wn->private_data;
 214         struct btr_node *btrn = wn->btrn;
 215         char *data;
 216         size_t bytes;
 217         snd_pcm_sframes_t frames;
 218         int ret;
 219
 220 again:
 221         t->error = 0;
 222         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 223         if (ret == 0)
 224                 return;
 225         btr_merge(btrn, wn->min_iqs);
 226         bytes = btr_next_buffer(btrn, &data);
 227         if (ret < 0 || bytes < pad->bytes_per_frame) { /* eof */
 228                 assert(btr_no_parent(btrn));
 229                 ret = -E_ALSA_EOF;
 230                 if (!pad->handle)
 231                         goto err;
 232                 /* wait until pending frames are played */
 233                 if (pad->drain_barrier.tv_sec == 0) {
 234                         PARA_DEBUG_LOG("waiting for device to drain\n");
 235                         tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
 236                                 &pad->drain_barrier);
 237                         return;
 238                 }
 239                 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
 240                         goto err;
 241                 return;
 242         }
 243         if (!pad->handle) {
 244                 int32_t val;
 245
 246                 if (bytes == 0) /* no data available */
 247                         return;
 248                 get_btr_sample_rate(btrn, &val);
 249                 pad->sample_rate = val;
 250                 get_btr_channels(btrn, &val);
 251                 pad->channels = val;
 252                 get_btr_sample_format(btrn, &val);
 253                 pad->sample_format = get_alsa_pcm_format(val);
 254
 255                 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
 256                         pad->sample_rate);
 257                 ret = alsa_init(pad, wn->conf);
 258                 if (ret < 0)
 259                         goto err;
 260                 wn->min_iqs = pad->bytes_per_frame;
 261         }
 262         frames = bytes / pad->bytes_per_frame;
 263         frames = snd_pcm_writei(pad->handle, data, frames);
 264         if (frames >= 0) {
 265                 btr_consume(btrn, frames * pad->bytes_per_frame);
 266                 goto again;
 267         }
 268         if (frames == -EPIPE) {
 269                 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
 270                 snd_pcm_prepare(pad->handle);
 271                 return;
 272         }
 273         if (frames == -EAGAIN)
 274                 return;
 275         PARA_WARNING_LOG("%s\n", snd_strerror(-frames));
 276         ret = -E_ALSA_WRITE;
 277 err:
 278         assert(ret < 0);
 279         btr_remove_node(btrn);
 280         t->error = ret;
 281 }
 282
 283 __malloc static void *alsa_parse_config(const char *options)
 284 {
 285         int ret;
 286         struct alsa_write_args_info *conf
 287                 = para_calloc(sizeof(struct alsa_write_args_info));
 288
 289         PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
 290         ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
 291         if (ret)
 292                 goto err_out;
 293         PARA_INFO_LOG("help given: %d\n", conf->help_given);
 294         return conf;
 295 err_out:
 296         free(conf);
 297         return NULL;
 298 }
 299
 300 static void alsa_free_config(void *conf)
 301 {
 302         alsa_cmdline_parser_free(conf);
 303 }
 304
 305 /**
 306  * The init function of the alsa writer.
 307  *
 308  * \param w Pointer to the writer to initialize.
 309  *
 310  * \sa struct \ref writer.
 311  */
 312 void alsa_write_init(struct writer *w)
 313 {
 314         struct alsa_write_args_info dummy;
 315
 316         alsa_cmdline_parser_init(&dummy);
 317         w->open = alsa_open;
 318         w->close = alsa_close;
 319         w->pre_select = alsa_write_pre_select;
 320         w->post_select = alsa_write_post_select;
 321         w->parse_config = alsa_parse_config;
 322         w->shutdown = NULL; /* nothing to do */
 323         w->free_config = alsa_free_config;
 324         w->help = (struct ggo_help) {
 325                 .short_help = alsa_write_args_info_help,
 326                 .detailed_help = alsa_write_args_info_detailed_help
 327         };
 328         alsa_cmdline_parser_free(&dummy);
 329 }