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 };
  56
  57 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
  58 {
  59         switch (sf) {
  60         case SF_S8: return SND_PCM_FORMAT_S8;
  61         case SF_U8: return SND_PCM_FORMAT_U8;
  62         case SF_S16_LE: return SND_PCM_FORMAT_S16_LE;
  63         case SF_S16_BE: return SND_PCM_FORMAT_S16_BE;
  64         case SF_U16_LE: return SND_PCM_FORMAT_U16_LE;
  65         case SF_U16_BE: return SND_PCM_FORMAT_U16_BE;
  66         default: return SND_PCM_FORMAT_S16_LE;
  67         }
  68 }
  69
  70 /* Install PCM software and hardware configuration. */
  71 static int alsa_init(struct private_alsa_write_data *pad,
  72                 struct alsa_write_args_info *conf)
  73 {
  74         snd_pcm_hw_params_t *hwparams;
  75         snd_pcm_sw_params_t *swparams;
  76         snd_pcm_uframes_t start_threshold, stop_threshold;
  77         snd_pcm_uframes_t period_size;
  78         int err;
  79
  80         PARA_INFO_LOG("opening %s\n", conf->device_arg);
  81         err = snd_pcm_open(&pad->handle, conf->device_arg,
  82                 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
  83         if (err < 0)
  84                 return -E_PCM_OPEN;
  85
  86         snd_pcm_hw_params_alloca(&hwparams);
  87         snd_pcm_sw_params_alloca(&swparams);
  88         if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
  89                 return -E_BROKEN_CONF;
  90         if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
  91                         SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
  92                 return -E_ACCESS_TYPE;
  93         if (snd_pcm_hw_params_set_format(pad->handle, hwparams,
  94                         pad->sample_format) < 0)
  95                 return -E_SAMPLE_FORMAT;
  96         if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
  97                         pad->channels) < 0)
  98                 return -E_CHANNEL_COUNT;
  99         if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
 100                         &pad->sample_rate, NULL) < 0)
 101                 return -E_SET_RATE;
 102         err = snd_pcm_hw_params_get_buffer_time_max(hwparams,
 103                 &pad->buffer_time, NULL);
 104         if (err < 0 || !pad->buffer_time)
 105                 return -E_GET_BUFFER_TIME;
 106         PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
 107         if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
 108                         &pad->buffer_time, NULL) < 0)
 109                 return -E_SET_BUFFER_TIME;
 110         if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
 111                 return -E_HW_PARAMS;
 112         snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
 113         snd_pcm_hw_params_get_buffer_size(hwparams, &pad->buffer_frames);
 114         PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad->buffer_frames,
 115                 period_size);
 116         if (period_size == pad->buffer_frames)
 117                 return -E_BAD_PERIOD;
 118         snd_pcm_sw_params_current(pad->handle, swparams);
 119         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 120         if (pad->buffer_frames < 1)
 121                 start_threshold = 1;
 122         else
 123                 start_threshold = PARA_MIN(pad->buffer_frames,
 124                         (snd_pcm_uframes_t)pad->sample_rate);
 125         if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 126                         start_threshold) < 0)
 127                 return -E_START_THRESHOLD;
 128         stop_threshold = pad->buffer_frames;
 129         if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 130                         stop_threshold) < 0)
 131                 return -E_STOP_THRESHOLD;
 132         if (snd_pcm_sw_params(pad->handle, swparams) < 0)
 133                 PARA_WARNING_LOG("unable to install sw params\n");
 134         pad->bytes_per_frame = snd_pcm_format_physical_width(pad->sample_format)
 135                 * pad->channels / 8;
 136         if (pad->bytes_per_frame <= 0)
 137                 return -E_PHYSICAL_WIDTH;
 138         PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
 139         if (snd_pcm_nonblock(pad->handle, 1))
 140                 PARA_ERROR_LOG("failed to set nonblock mode\n");
 141         return 1;
 142 }
 143
 144 static void alsa_write_pre_select(struct sched *s, struct task *t)
 145 {
 146         struct writer_node *wn = container_of(t, struct writer_node, task);
 147         struct private_alsa_write_data *pad = wn->private_data;
 148         snd_pcm_sframes_t avail, underrun;
 149         int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 150
 151         if (ret == 0)
 152                 return;
 153         if (!pad) {
 154                 sched_min_delay(s);
 155                 return;
 156         }
 157         if (ret < 0) {
 158                 sched_request_barrier_or_min_delay(&pad->drain_barrier, s);
 159                 return;
 160         }
 161         /*
 162          * Data is available to be written to the alsa handle.  Compute number
 163          * of milliseconds until next buffer underrun would occur.
 164          *
 165          * snd_pcm_avail_update() updates the current available count of
 166          * samples for writing.  It is a light method to obtain current stream
 167          * position, because it does not require the user <-> kernel context
 168          * switch, but the value is less accurate, because ring buffer pointers
 169          * are updated in kernel drivers only when an interrupt occurs.
 170          */
 171         avail = snd_pcm_avail_update(pad->handle);
 172         if (avail < 0)
 173                 avail = 0;
 174         underrun = (pad->buffer_frames - avail) * pad->buffer_time
 175                 / pad->buffer_frames / 1000;
 176         if (underrun < 50)
 177                 underrun = 50;
 178         underrun -= 50;
 179         sched_request_timeout_ms(underrun, s);
 180 }
 181
 182 static void alsa_close(struct writer_node *wn)
 183 {
 184         struct private_alsa_write_data *pad = wn->private_data;
 185         PARA_INFO_LOG("closing writer node %p\n", wn);
 186
 187         if (!pad)
 188                 return;
 189         /*
 190          * It's OK to have a blocking operation here because we already made
 191          * sure that the PCM output buffer is (nearly) empty.
 192          */
 193         snd_pcm_nonblock(pad->handle, 0);
 194         snd_pcm_drain(pad->handle);
 195         snd_pcm_close(pad->handle);
 196         snd_config_update_free_global();
 197         free(pad);
 198 }
 199
 200 static void alsa_write_post_select(__a_unused struct sched *s,
 201                 struct task *t)
 202 {
 203         struct writer_node *wn = container_of(t, struct writer_node, task);
 204         struct private_alsa_write_data *pad = wn->private_data;
 205         struct btr_node *btrn = wn->btrn;
 206         char *data;
 207         size_t bytes;
 208         snd_pcm_sframes_t frames;
 209         int ret;
 210
 211 again:
 212         t->error = 0;
 213         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 214         if (ret == 0)
 215                 return;
 216         btr_merge(btrn, wn->min_iqs);
 217         bytes = btr_next_buffer(btrn, &data);
 218         if (ret < 0 || bytes < wn->min_iqs) { /* eof */
 219                 assert(btr_no_parent(btrn));
 220                 ret = -E_WRITE_COMMON_EOF;
 221                 if (!pad)
 222                         goto err;
 223                 /* wait until pending frames are played */
 224                 if (pad->drain_barrier.tv_sec == 0) {
 225                         PARA_DEBUG_LOG("waiting for device to drain\n");
 226                         tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
 227                                 &pad->drain_barrier);
 228                         return;
 229                 }
 230                 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
 231                         goto err;
 232                 return;
 233         }
 234         if (!pad) {
 235                 int32_t val;
 236
 237                 if (bytes == 0) /* no data available */
 238                         return;
 239                 pad = para_calloc(sizeof(*pad));
 240                 get_btr_sample_rate(btrn, &val);
 241                 pad->sample_rate = val;
 242                 get_btr_channels(btrn, &val);
 243                 pad->channels = val;
 244                 get_btr_sample_format(btrn, &val);
 245                 pad->sample_format = get_alsa_pcm_format(val);
 246
 247                 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
 248                         pad->sample_rate);
 249                 ret = alsa_init(pad, wn->conf);
 250                 if (ret < 0) {
 251                         free(pad);
 252                         goto err;
 253                 }
 254                 wn->private_data = pad;
 255                 wn->min_iqs = pad->bytes_per_frame;
 256                 goto again;
 257         }
 258         frames = bytes / pad->bytes_per_frame;
 259         frames = snd_pcm_writei(pad->handle, data, frames);
 260         if (frames == 0 || frames == -EAGAIN)
 261                 return;
 262         if (frames > 0) {
 263                 btr_consume(btrn, frames * pad->bytes_per_frame);
 264                 goto again;
 265         }
 266         if (frames == -EPIPE) {
 267                 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
 268                 snd_pcm_prepare(pad->handle);
 269                 return;
 270         }
 271         PARA_WARNING_LOG("%s\n", snd_strerror(-frames));
 272         ret = -E_ALSA_WRITE;
 273 err:
 274         assert(ret < 0);
 275         btr_remove_node(btrn);
 276         t->error = ret;
 277 }
 278
 279 __malloc static void *alsa_parse_config_or_die(const char *options)
 280 {
 281         struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
 282
 283         /* exits on errors */
 284         alsa_cmdline_parser_string(options, conf, "alsa_write");
 285         return conf;
 286 }
 287
 288 static void alsa_free_config(void *conf)
 289 {
 290         alsa_cmdline_parser_free(conf);
 291 }
 292
 293 /**
 294  * The init function of the alsa writer.
 295  *
 296  * \param w Pointer to the writer to initialize.
 297  *
 298  * \sa struct \ref writer.
 299  */
 300 void alsa_write_init(struct writer *w)
 301 {
 302         struct alsa_write_args_info dummy;
 303
 304         alsa_cmdline_parser_init(&dummy);
 305         w->close = alsa_close;
 306         w->pre_select = alsa_write_pre_select;
 307         w->post_select = alsa_write_post_select;
 308         w->parse_config_or_die = alsa_parse_config_or_die;
 309         w->shutdown = NULL; /* nothing to do */
 310         w->free_config = alsa_free_config;
 311         w->help = (struct ggo_help) {
 312                 .short_help = alsa_write_args_info_help,
 313                 .detailed_help = alsa_write_args_info_detailed_help
 314         };
 315         alsa_cmdline_parser_free(&dummy);
 316 }