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 /** always use 16 bit little endian */
  35 #define FORMAT SND_PCM_FORMAT_S16_LE
  36
  37 /** Data specific to the alsa writer. */
  38 struct private_alsa_write_data {
  39         /** The alsa handle */
  40         snd_pcm_t *handle;
  41         /** Determined and set by alsa_open(). */
  42         int bytes_per_frame;
  43         /** The approximate maximum buffer duration in us. */
  44         unsigned buffer_time;
  45         /* Number of frames that fit into the buffer. */
  46         snd_pcm_uframes_t buffer_frames;
  47         /**
  48          * The samplerate given by command line option or the decoder
  49          * of the writer node group.
  50          */
  51         unsigned samplerate;
  52         /**
  53          * The number of channels, given by command line option or the
  54          * decoder of the writer node group.
  55          */
  56         unsigned channels;
  57         struct timeval drain_barrier;
  58 };
  59
  60 /* Install PCM software and hardware configuration. */
  61 static int alsa_init(struct private_alsa_write_data *pad,
  62                 struct alsa_write_args_info *conf)
  63 {
  64         snd_pcm_hw_params_t *hwparams;
  65         snd_pcm_sw_params_t *swparams;
  66         snd_pcm_uframes_t start_threshold, stop_threshold;
  67         snd_pcm_uframes_t period_size;
  68         int err;
  69
  70         PARA_INFO_LOG("opening %s\n", conf->device_arg);
  71         err = snd_pcm_open(&pad->handle, conf->device_arg,
  72                 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
  73         if (err < 0)
  74                 return -E_PCM_OPEN;
  75
  76         snd_pcm_hw_params_alloca(&hwparams);
  77         snd_pcm_sw_params_alloca(&swparams);
  78         if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
  79                 return -E_BROKEN_CONF;
  80         if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
  81                         SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
  82                 return -E_ACCESS_TYPE;
  83         if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
  84                 return -E_SAMPLE_FORMAT;
  85         if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
  86                         pad->channels) < 0)
  87                 return -E_CHANNEL_COUNT;
  88         if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
  89                         &pad->samplerate, NULL) < 0)
  90                 return -E_SET_RATE;
  91         err = snd_pcm_hw_params_get_buffer_time_max(hwparams,
  92                 &pad->buffer_time, NULL);
  93         if (err < 0 || !pad->buffer_time)
  94                 return -E_GET_BUFFER_TIME;
  95         PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
  96         if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
  97                         &pad->buffer_time, NULL) < 0)
  98                 return -E_SET_BUFFER_TIME;
  99         if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
 100                 return -E_HW_PARAMS;
 101         snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
 102         snd_pcm_hw_params_get_buffer_size(hwparams, &pad->buffer_frames);
 103         PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad->buffer_frames,
 104                 period_size);
 105         if (period_size == pad->buffer_frames)
 106                 return -E_BAD_PERIOD;
 107         snd_pcm_sw_params_current(pad->handle, swparams);
 108         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 109         if (pad->buffer_frames < 1)
 110                 start_threshold = 1;
 111         else
 112                 start_threshold = PARA_MIN(pad->buffer_frames,
 113                         (snd_pcm_uframes_t)pad->samplerate);
 114         if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 115                         start_threshold) < 0)
 116                 return -E_START_THRESHOLD;
 117         stop_threshold = pad->buffer_frames;
 118         if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 119                         stop_threshold) < 0)
 120                 return -E_STOP_THRESHOLD;
 121         if (snd_pcm_sw_params(pad->handle, swparams) < 0)
 122                 PARA_WARNING_LOG("unable to install sw params\n");
 123         pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
 124                 * pad->channels / 8;
 125         if (pad->bytes_per_frame <= 0)
 126                 return -E_PHYSICAL_WIDTH;
 127         PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
 128         if (snd_pcm_nonblock(pad->handle, 1))
 129                 PARA_ERROR_LOG("failed to set nonblock mode\n");
 130         return 1;
 131 }
 132
 133 /* Open an instance of the alsa writer. */
 134 static int alsa_open(struct writer_node *wn)
 135 {
 136         wn->private_data = para_calloc(sizeof(struct private_alsa_write_data));
 137         return 1;
 138 }
 139
 140 static void alsa_write_pre_select(struct sched *s, struct task *t)
 141 {
 142         struct writer_node *wn = container_of(t, struct writer_node, task);
 143         struct private_alsa_write_data *pad = wn->private_data;
 144         struct timeval tv;
 145         snd_pcm_sframes_t avail, underrun;
 146         int ret;
 147
 148         if (!pad->handle)
 149                 return;
 150         ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 151         if (ret < 0)
 152                 sched_request_timeout_ms(20, s);
 153         if (ret <= 0)
 154                 return;
 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         ms2tv(underrun, &tv);
 174         if (tv_diff(&s->timeout, &tv, NULL) > 0)
 175                 s->timeout = tv;
 176 }
 177
 178 static void alsa_close(struct writer_node *wn)
 179 {
 180         struct private_alsa_write_data *pad = wn->private_data;
 181         PARA_INFO_LOG("closing writer node %p\n", wn);
 182
 183         if (pad->handle) {
 184                 /*
 185                  * It's OK to have a blocking operation here because we already
 186                  * made sure that the PCM output buffer is (nearly) empty.
 187                  */
 188                 snd_pcm_nonblock(pad->handle, 0);
 189                 snd_pcm_drain(pad->handle);
 190                 snd_pcm_close(pad->handle);
 191                 snd_config_update_free_global();
 192         }
 193         free(pad);
 194 }
 195
 196 static void alsa_write_post_select(__a_unused struct sched *s,
 197                 struct task *t)
 198 {
 199         struct writer_node *wn = container_of(t, struct writer_node, task);
 200         struct private_alsa_write_data *pad = wn->private_data;
 201         struct btr_node *btrn = wn->btrn;
 202         char *data;
 203         size_t bytes;
 204         snd_pcm_sframes_t frames;
 205         int ret;
 206
 207 again:
 208         t->error = 0;
 209         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 210         if (ret == 0)
 211                 return;
 212         btr_merge(btrn, wn->min_iqs);
 213         bytes = btr_next_buffer(btrn, &data);
 214         if (ret < 0 || bytes < pad->bytes_per_frame) { /* eof */
 215                 assert(btr_no_parent(btrn));
 216                 ret = -E_ALSA_EOF;
 217                 if (!pad->handle)
 218                         goto err;
 219                 /* wait until pending frames are played */
 220                 if (pad->drain_barrier.tv_sec == 0) {
 221                         PARA_DEBUG_LOG("waiting for device to drain\n");
 222                         tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
 223                                 &pad->drain_barrier);
 224                         return;
 225                 }
 226                 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
 227                         goto err;
 228                 return;
 229         }
 230         if (!pad->handle) {
 231                 struct alsa_write_args_info *conf = wn->conf;
 232                 if (bytes == 0) /* no data available */
 233                         return;
 234                 /* defaults */
 235                 pad->samplerate = conf->samplerate_arg;
 236                 pad->channels = conf->channels_arg;
 237                 if (!conf->samplerate_given) { /* config option trumps btr_exec */
 238                         int32_t rate;
 239                         if (get_btr_samplerate(btrn, &rate) >= 0)
 240                                 pad->samplerate = rate;
 241                 }
 242                 if (!conf->channels_given) {
 243                         int32_t ch;
 244                         if (get_btr_channels(btrn, &ch) >= 0)
 245                                 pad->channels = ch;
 246                 }
 247                 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
 248                 ret = alsa_init(pad, wn->conf);
 249                 if (ret < 0)
 250                         goto err;
 251                 wn->min_iqs = pad->bytes_per_frame;
 252         }
 253         frames = bytes / pad->bytes_per_frame;
 254         frames = snd_pcm_writei(pad->handle, data, frames);
 255         if (frames >= 0) {
 256                 btr_consume(btrn, frames * pad->bytes_per_frame);
 257                 goto again;
 258         }
 259         if (frames == -EPIPE) {
 260                 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
 261                 snd_pcm_prepare(pad->handle);
 262                 return;
 263         }
 264         if (frames == -EAGAIN)
 265                 return;
 266         PARA_WARNING_LOG("%s\n", snd_strerror(-frames));
 267         ret = -E_ALSA_WRITE;
 268 err:
 269         assert(ret < 0);
 270         btr_remove_node(btrn);
 271         t->error = ret;
 272 }
 273
 274 __malloc static void *alsa_parse_config(const char *options)
 275 {
 276         int ret;
 277         struct alsa_write_args_info *conf
 278                 = para_calloc(sizeof(struct alsa_write_args_info));
 279
 280         PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
 281         ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
 282         if (ret)
 283                 goto err_out;
 284         PARA_INFO_LOG("help given: %d\n", conf->help_given);
 285         return conf;
 286 err_out:
 287         free(conf);
 288         return NULL;
 289 }
 290
 291 static void alsa_free_config(void *conf)
 292 {
 293         alsa_cmdline_parser_free(conf);
 294 }
 295
 296 /**
 297  * The init function of the alsa writer.
 298  *
 299  * \param w Pointer to the writer to initialize.
 300  *
 301  * \sa struct \ref writer.
 302  */
 303 void alsa_write_init(struct writer *w)
 304 {
 305         struct alsa_write_args_info dummy;
 306
 307         alsa_cmdline_parser_init(&dummy);
 308         w->open = alsa_open;
 309         w->close = alsa_close;
 310         w->pre_select = alsa_write_pre_select;
 311         w->post_select = alsa_write_post_select;
 312         w->parse_config = alsa_parse_config;
 313         w->shutdown = NULL; /* nothing to do */
 314         w->free_config = alsa_free_config;
 315         w->help = (struct ggo_help) {
 316                 .short_help = alsa_write_args_info_help,
 317                 .detailed_help = alsa_write_args_info_detailed_help
 318         };
 319         alsa_cmdline_parser_free(&dummy);
 320 }