alsa_write.c

   1 /*
   2  * Copyright (C) 2005-2009 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 };
  58
  59 /* Install PCM software and hardware configuration. */
  60 static int alsa_init(struct private_alsa_write_data *pad,
  61                 struct alsa_write_args_info *conf)
  62 {
  63         snd_pcm_hw_params_t *hwparams;
  64         snd_pcm_sw_params_t *swparams;
  65         snd_pcm_uframes_t start_threshold, stop_threshold;
  66         snd_pcm_uframes_t period_size;
  67         int err;
  68
  69         PARA_INFO_LOG("opening %s\n", conf->device_arg);
  70         err = snd_pcm_open(&pad->handle, conf->device_arg,
  71                 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
  72         if (err < 0)
  73                 return -E_PCM_OPEN;
  74
  75         snd_pcm_hw_params_alloca(&hwparams);
  76         snd_pcm_sw_params_alloca(&swparams);
  77         if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
  78                 return -E_BROKEN_CONF;
  79         if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
  80                         SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
  81                 return -E_ACCESS_TYPE;
  82         if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
  83                 return -E_SAMPLE_FORMAT;
  84         if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
  85                         pad->channels) < 0)
  86                 return -E_CHANNEL_COUNT;
  87         if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
  88                         &pad->samplerate, NULL) < 0)
  89                 return -E_SET_RATE;
  90         err = snd_pcm_hw_params_get_buffer_time_max(hwparams,
  91                 &pad->buffer_time, NULL);
  92         if (err < 0 || !pad->buffer_time)
  93                 return -E_GET_BUFFER_TIME;
  94         PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
  95         if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
  96                         &pad->buffer_time, NULL) < 0)
  97                 return -E_SET_BUFFER_TIME;
  98         if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
  99                 return -E_HW_PARAMS;
 100         snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
 101         snd_pcm_hw_params_get_buffer_size(hwparams, &pad->buffer_frames);
 102         PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad->buffer_frames,
 103                 period_size);
 104         if (period_size == pad->buffer_frames)
 105                 return -E_BAD_PERIOD;
 106         snd_pcm_sw_params_current(pad->handle, swparams);
 107         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 108         if (pad->buffer_frames < 1)
 109                 start_threshold = 1;
 110         else
 111                 start_threshold = PARA_MIN(pad->buffer_frames,
 112                         (snd_pcm_uframes_t)pad->samplerate);
 113         if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 114                         start_threshold) < 0)
 115                 return -E_START_THRESHOLD;
 116         stop_threshold = pad->buffer_frames;
 117         if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 118                         stop_threshold) < 0)
 119                 return -E_STOP_THRESHOLD;
 120         if (snd_pcm_sw_params(pad->handle, swparams) < 0)
 121                 PARA_WARNING_LOG("unable to install sw params\n");
 122         pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
 123                 * pad->channels / 8;
 124         if (pad->bytes_per_frame <= 0)
 125                 return -E_PHYSICAL_WIDTH;
 126         PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
 127         if (snd_pcm_nonblock(pad->handle, 1))
 128                 PARA_ERROR_LOG("failed to set nonblock mode\n");
 129         return 1;
 130 }
 131
 132 /* Open an instance of the alsa writer. */
 133 static int alsa_open(struct writer_node *wn)
 134 {
 135         wn->private_data = para_calloc(sizeof(struct private_alsa_write_data));
 136         return 1;
 137 }
 138
 139 static void alsa_write_pre_select_btr(struct sched *s, struct task *t)
 140 {
 141         struct writer_node *wn = container_of(t, struct writer_node, task);
 142         struct private_alsa_write_data *pad = wn->private_data;
 143         struct timeval tv;
 144         snd_pcm_sframes_t avail, underrun;
 145         int ret;
 146
 147         if (!pad->handle)
 148                 return;
 149         ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 150         if (ret < 0)
 151                 sched_request_timeout_ms(20, s);
 152         if (ret <= 0)
 153                 return;
 154         /*
 155          * Data is available to be written to the alsa handle.  Compute number
 156          * of milliseconds until next buffer underrun would occur.
 157          *
 158          * snd_pcm_avail_update() updates the current available count of
 159          * samples for writing.  It is a light method to obtain current stream
 160          * position, because it does not require the user <-> kernel context
 161          * switch, but the value is less accurate, because ring buffer pointers
 162          * are updated in kernel drivers only when an interrupt occurs.
 163          */
 164         avail = snd_pcm_avail_update(pad->handle);
 165         if (avail < 0)
 166                 avail = 0;
 167         underrun = (pad->buffer_frames - avail) * pad->buffer_time
 168                 / pad->buffer_frames / 1000;
 169         if (underrun < 50)
 170                 underrun = 50;
 171         underrun -= 50;
 172         ms2tv(underrun, &tv);
 173         if (tv_diff(&s->timeout, &tv, NULL) > 0)
 174                 s->timeout = tv;
 175 }
 176
 177 static void xrun(snd_pcm_t *handle)
 178 {
 179         snd_pcm_status_t *status;
 180         int ret;
 181         struct timeval tv, diff;
 182
 183         snd_pcm_status_alloca(&status);
 184         ret = snd_pcm_status(handle, status);
 185         if (ret < 0)
 186                 return;
 187         if (snd_pcm_status_get_state(status) != SND_PCM_STATE_XRUN)
 188                 return;
 189         snd_pcm_status_get_trigger_tstamp(status, &tv);
 190         tv_diff(now, &tv, &diff);
 191         PARA_WARNING_LOG("underrun: %lums\n", tv2ms(&diff));
 192 }
 193
 194 static void alsa_close(struct writer_node *wn)
 195 {
 196         struct private_alsa_write_data *pad = wn->private_data;
 197         PARA_INFO_LOG("closing writer node %p\n", wn);
 198
 199         if (pad->handle) {
 200                 /*
 201                  * It's OK to have a blocking operation here because we already
 202                  * made sure that the PCM output buffer is (nearly) empty.
 203                  */
 204                 snd_pcm_nonblock(pad->handle, 0);
 205                 snd_pcm_drain(pad->handle);
 206                 snd_pcm_close(pad->handle);
 207                 snd_config_update_free_global();
 208         }
 209         free(pad);
 210 }
 211
 212 static void alsa_write_post_select_btr(__a_unused struct sched *s,
 213                 struct task *t)
 214 {
 215         struct writer_node *wn = container_of(t, struct writer_node, task);
 216         struct private_alsa_write_data *pad = wn->private_data;
 217         struct btr_node *btrn = wn->btrn;
 218         char *data;
 219         size_t bytes;
 220         snd_pcm_sframes_t frames, avail;
 221         int ret;
 222
 223 again:
 224         t->error = 0;
 225         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 226         if (ret == 0)
 227                 return;
 228         btr_merge(btrn, wn->min_iqs);
 229         bytes = btr_next_buffer(btrn, &data);
 230         if (ret < 0 || bytes < pad->bytes_per_frame) { /* eof */
 231                 assert(btr_no_parent(btrn));
 232                 ret = -E_ALSA_EOF;
 233                 if (!pad->handle)
 234                         goto err;
 235                 /* wait until pending frames are played */
 236                 avail = snd_pcm_avail_update(pad->handle);
 237                 if (avail + 1000 > pad->buffer_frames)
 238                         goto err;
 239                 PARA_DEBUG_LOG("waiting for device to drain\n");
 240                 return;
 241         }
 242         if (!pad->handle) {
 243                 struct alsa_write_args_info *conf = wn->conf;
 244                 if (bytes == 0) /* no data available */
 245                         return;
 246                 /* defaults */
 247                 pad->samplerate = conf->samplerate_arg;
 248                 pad->channels = conf->channels_arg;
 249                 if (!conf->samplerate_given) { /* config option trumps btr_exec */
 250                         int32_t rate;
 251                         if (get_btr_samplerate(btrn, &rate) >= 0)
 252                                 pad->samplerate = rate;
 253                 }
 254                 if (!conf->channels_given) {
 255                         int32_t ch;
 256                         if (get_btr_channels(btrn, &ch) >= 0)
 257                                 pad->channels = ch;
 258                 }
 259                 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
 260                 ret = alsa_init(pad, wn->conf);
 261                 if (ret < 0)
 262                         goto err;
 263                 wn->min_iqs = pad->bytes_per_frame;
 264         }
 265         frames = bytes / pad->bytes_per_frame;
 266         frames = snd_pcm_writei(pad->handle, data, frames);
 267         if (frames >= 0) {
 268                 btr_consume(btrn, frames * pad->bytes_per_frame);
 269                 goto again;
 270         }
 271         if (frames == -EPIPE) {
 272                 xrun(pad->handle);
 273                 snd_pcm_prepare(pad->handle);
 274                 return;
 275         }
 276         if (frames == -EAGAIN)
 277                 return;
 278         PARA_WARNING_LOG("%s\n", snd_strerror(-frames));
 279         ret = -E_ALSA_WRITE;
 280 err:
 281         assert(ret < 0);
 282         btr_remove_node(btrn);
 283         t->error = ret;
 284 }
 285
 286 __malloc static void *alsa_parse_config(const char *options)
 287 {
 288         int ret;
 289         struct alsa_write_args_info *conf
 290                 = para_calloc(sizeof(struct alsa_write_args_info));
 291
 292         PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
 293         ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
 294         if (ret)
 295                 goto err_out;
 296         PARA_INFO_LOG("help given: %d\n", conf->help_given);
 297         return conf;
 298 err_out:
 299         free(conf);
 300         return NULL;
 301 }
 302
 303 static void alsa_free_config(void *conf)
 304 {
 305         alsa_cmdline_parser_free(conf);
 306 }
 307
 308 /**
 309  * The init function of the alsa writer.
 310  *
 311  * \param w Pointer to the writer to initialize.
 312  *
 313  * \sa \ref struct writer.
 314  */
 315 void alsa_write_init(struct writer *w)
 316 {
 317         struct alsa_write_args_info dummy;
 318
 319         alsa_cmdline_parser_init(&dummy);
 320         w->open = alsa_open;
 321         w->close = alsa_close;
 322         w->pre_select_btr = alsa_write_pre_select_btr;
 323         w->post_select_btr = alsa_write_post_select_btr;
 324         w->parse_config = alsa_parse_config;
 325         w->shutdown = NULL; /* nothing to do */
 326         w->free_config = alsa_free_config;
 327         w->help = (struct ggo_help) {
 328                 .short_help = alsa_write_args_info_help,
 329                 .detailed_help = alsa_write_args_info_detailed_help
 330         };
 331         alsa_cmdline_parser_free(&dummy);
 332 }