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 (ret < 0 || !pad)
 154                 return sched_min_delay(s);
 155         /*
 156          * Data is available to be written to the alsa handle.  Compute number
 157          * of milliseconds until next buffer underrun would occur.
 158          *
 159          * snd_pcm_avail_update() updates the current available count of
 160          * samples for writing.  It is a light method to obtain current stream
 161          * position, because it does not require the user <-> kernel context
 162          * switch, but the value is less accurate, because ring buffer pointers
 163          * are updated in kernel drivers only when an interrupt occurs.
 164          */
 165         avail = snd_pcm_avail_update(pad->handle);
 166         if (avail < 0)
 167                 avail = 0;
 168         underrun = (pad->buffer_frames - avail) * pad->buffer_time
 169                 / pad->buffer_frames / 1000;
 170         if (underrun < 50)
 171                 underrun = 50;
 172         underrun -= 50;
 173         sched_request_timeout_ms(underrun, s);
 174 }
 175
 176 static void alsa_close(struct writer_node *wn)
 177 {
 178         struct private_alsa_write_data *pad = wn->private_data;
 179         PARA_INFO_LOG("closing writer node %p\n", wn);
 180
 181         if (!pad)
 182                 return;
 183         /*
 184          * It's OK to have a blocking operation here because we already made
 185          * sure that the PCM output buffer is (nearly) empty.
 186          */
 187         snd_pcm_nonblock(pad->handle, 0);
 188         snd_pcm_drain(pad->handle);
 189         snd_pcm_close(pad->handle);
 190         snd_config_update_free_global();
 191         free(pad);
 192 }
 193
 194 static void alsa_write_post_select(__a_unused struct sched *s,
 195                 struct task *t)
 196 {
 197         struct writer_node *wn = container_of(t, struct writer_node, task);
 198         struct private_alsa_write_data *pad = wn->private_data;
 199         struct btr_node *btrn = wn->btrn;
 200         char *data;
 201         size_t bytes;
 202         snd_pcm_sframes_t frames;
 203         int ret;
 204
 205 again:
 206         t->error = 0;
 207         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 208         if (ret == 0)
 209                 return;
 210         btr_merge(btrn, wn->min_iqs);
 211         bytes = btr_next_buffer(btrn, &data);
 212         if (ret < 0 || bytes < wn->min_iqs) { /* eof */
 213                 assert(btr_no_parent(btrn));
 214                 ret = -E_WRITE_COMMON_EOF;
 215                 if (!pad)
 216                         goto err;
 217                 /* wait until pending frames are played */
 218                 if (pad->drain_barrier.tv_sec == 0) {
 219                         PARA_DEBUG_LOG("waiting for device to drain\n");
 220                         tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
 221                                 &pad->drain_barrier);
 222                         return;
 223                 }
 224                 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
 225                         goto err;
 226                 return;
 227         }
 228         if (!pad) {
 229                 int32_t val;
 230
 231                 if (bytes == 0) /* no data available */
 232                         return;
 233                 pad = para_calloc(sizeof(*pad));
 234                 get_btr_sample_rate(btrn, &val);
 235                 pad->sample_rate = val;
 236                 get_btr_channels(btrn, &val);
 237                 pad->channels = val;
 238                 get_btr_sample_format(btrn, &val);
 239                 pad->sample_format = get_alsa_pcm_format(val);
 240
 241                 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
 242                         pad->sample_rate);
 243                 ret = alsa_init(pad, wn->conf);
 244                 if (ret < 0) {
 245                         free(pad);
 246                         goto err;
 247                 }
 248                 wn->private_data = pad;
 249                 wn->min_iqs = pad->bytes_per_frame;
 250                 goto again;
 251         }
 252         frames = bytes / pad->bytes_per_frame;
 253         frames = snd_pcm_writei(pad->handle, data, frames);
 254         if (frames >= 0) {
 255                 btr_consume(btrn, frames * pad->bytes_per_frame);
 256                 goto again;
 257         }
 258         if (frames == -EPIPE) {
 259                 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
 260                 snd_pcm_prepare(pad->handle);
 261                 return;
 262         }
 263         if (frames == -EAGAIN)
 264                 return;
 265         PARA_WARNING_LOG("%s\n", snd_strerror(-frames));
 266         ret = -E_ALSA_WRITE;
 267 err:
 268         assert(ret < 0);
 269         btr_remove_node(btrn);
 270         t->error = ret;
 271 }
 272
 273 __malloc static void *alsa_parse_config_or_die(const char *options)
 274 {
 275         struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
 276
 277         PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
 278         /* exits on errors */
 279         alsa_cmdline_parser_string(options, conf, "alsa_write");
 280         return conf;
 281 }
 282
 283 static void alsa_free_config(void *conf)
 284 {
 285         alsa_cmdline_parser_free(conf);
 286 }
 287
 288 /**
 289  * The init function of the alsa writer.
 290  *
 291  * \param w Pointer to the writer to initialize.
 292  *
 293  * \sa struct \ref writer.
 294  */
 295 void alsa_write_init(struct writer *w)
 296 {
 297         struct alsa_write_args_info dummy;
 298
 299         alsa_cmdline_parser_init(&dummy);
 300         w->close = alsa_close;
 301         w->pre_select = alsa_write_pre_select;
 302         w->post_select = alsa_write_post_select;
 303         w->parse_config_or_die = alsa_parse_config_or_die;
 304         w->shutdown = NULL; /* nothing to do */
 305         w->free_config = alsa_free_config;
 306         w->help = (struct ggo_help) {
 307                 .short_help = alsa_write_args_info_help,
 308                 .detailed_help = alsa_write_args_info_detailed_help
 309         };
 310         alsa_cmdline_parser_free(&dummy);
 311 }