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 <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_init(). */
  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         snd_pcm_format_t sample_format;
  50         /**
  51          * The number of channels, given by command line option or the
  52          * decoder of the writer node group.
  53          */
  54         unsigned channels;
  55         struct timeval drain_barrier;
  56 };
  57
  58 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
  59 {
  60         switch (sf) {
  61         case SF_S8: return SND_PCM_FORMAT_S8;
  62         case SF_U8: return SND_PCM_FORMAT_U8;
  63         case SF_S16_LE: return SND_PCM_FORMAT_S16_LE;
  64         case SF_S16_BE: return SND_PCM_FORMAT_S16_BE;
  65         case SF_U16_LE: return SND_PCM_FORMAT_U16_LE;
  66         case SF_U16_BE: return SND_PCM_FORMAT_U16_BE;
  67         default: return SND_PCM_FORMAT_S16_LE;
  68         }
  69 }
  70
  71 /* Install PCM software and hardware configuration. */
  72 static int alsa_init(struct private_alsa_write_data *pad,
  73                 struct alsa_write_args_info *conf)
  74 {
  75         snd_pcm_hw_params_t *hwparams;
  76         snd_pcm_sw_params_t *swparams;
  77         snd_pcm_uframes_t start_threshold, stop_threshold;
  78         snd_pcm_uframes_t period_size;
  79         int err;
  80
  81         PARA_INFO_LOG("opening %s\n", conf->device_arg);
  82         err = snd_pcm_open(&pad->handle, conf->device_arg,
  83                 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
  84         if (err < 0)
  85                 return -E_PCM_OPEN;
  86
  87         snd_pcm_hw_params_alloca(&hwparams);
  88         snd_pcm_sw_params_alloca(&swparams);
  89         if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
  90                 return -E_BROKEN_CONF;
  91         if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
  92                         SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
  93                 return -E_ACCESS_TYPE;
  94         if (snd_pcm_hw_params_set_format(pad->handle, hwparams,
  95                         pad->sample_format) < 0)
  96                 return -E_SAMPLE_FORMAT;
  97         if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
  98                         pad->channels) < 0)
  99                 return -E_CHANNEL_COUNT;
 100         if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
 101                         &pad->sample_rate, NULL) < 0)
 102                 return -E_SET_RATE;
 103         err = snd_pcm_hw_params_get_buffer_time_max(hwparams,
 104                 &pad->buffer_time, NULL);
 105         if (err < 0 || !pad->buffer_time)
 106                 return -E_GET_BUFFER_TIME;
 107         PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
 108         if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
 109                         &pad->buffer_time, NULL) < 0)
 110                 return -E_SET_BUFFER_TIME;
 111         if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
 112                 return -E_HW_PARAMS;
 113         snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
 114         snd_pcm_hw_params_get_buffer_size(hwparams, &pad->buffer_frames);
 115         PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad->buffer_frames,
 116                 period_size);
 117         if (period_size == pad->buffer_frames)
 118                 return -E_BAD_PERIOD;
 119         snd_pcm_sw_params_current(pad->handle, swparams);
 120         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 121         if (pad->buffer_frames < 1)
 122                 start_threshold = 1;
 123         else
 124                 start_threshold = PARA_MIN(pad->buffer_frames,
 125                         (snd_pcm_uframes_t)pad->sample_rate);
 126         if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 127                         start_threshold) < 0)
 128                 return -E_START_THRESHOLD;
 129         stop_threshold = pad->buffer_frames;
 130         if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 131                         stop_threshold) < 0)
 132                 return -E_STOP_THRESHOLD;
 133         if (snd_pcm_sw_params(pad->handle, swparams) < 0)
 134                 PARA_WARNING_LOG("unable to install sw params\n");
 135         pad->bytes_per_frame = snd_pcm_format_physical_width(pad->sample_format)
 136                 * pad->channels / 8;
 137         if (pad->bytes_per_frame <= 0)
 138                 return -E_PHYSICAL_WIDTH;
 139         PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
 140         if (snd_pcm_nonblock(pad->handle, 1))
 141                 PARA_ERROR_LOG("failed to set nonblock mode\n");
 142         return 1;
 143 }
 144
 145 static void alsa_write_pre_select(struct sched *s, struct task *t)
 146 {
 147         struct writer_node *wn = container_of(t, struct writer_node, task);
 148         struct private_alsa_write_data *pad = wn->private_data;
 149         struct timeval tv;
 150         snd_pcm_sframes_t avail, underrun;
 151         int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 152
 153         if (ret == 0)
 154                 return;
 155         if (ret < 0 || !pad)
 156                 return sched_min_delay(s);
 157         /*
 158          * Data is available to be written to the alsa handle.  Compute number
 159          * of milliseconds until next buffer underrun would occur.
 160          *
 161          * snd_pcm_avail_update() updates the current available count of
 162          * samples for writing.  It is a light method to obtain current stream
 163          * position, because it does not require the user <-> kernel context
 164          * switch, but the value is less accurate, because ring buffer pointers
 165          * are updated in kernel drivers only when an interrupt occurs.
 166          */
 167         avail = snd_pcm_avail_update(pad->handle);
 168         if (avail < 0)
 169                 avail = 0;
 170         underrun = (pad->buffer_frames - avail) * pad->buffer_time
 171                 / pad->buffer_frames / 1000;
 172         if (underrun < 50)
 173                 underrun = 50;
 174         underrun -= 50;
 175         ms2tv(underrun, &tv);
 176         sched_request_timeout(&tv, s);
 177 }
 178
 179 static void alsa_close(struct writer_node *wn)
 180 {
 181         struct private_alsa_write_data *pad = wn->private_data;
 182         PARA_INFO_LOG("closing writer node %p\n", wn);
 183
 184         if (!pad)
 185                 return;
 186         /*
 187          * It's OK to have a blocking operation here because we already made
 188          * sure that the PCM output buffer is (nearly) empty.
 189          */
 190         snd_pcm_nonblock(pad->handle, 0);
 191         snd_pcm_drain(pad->handle);
 192         snd_pcm_close(pad->handle);
 193         snd_config_update_free_global();
 194         free(pad);
 195 }
 196
 197 static void alsa_write_post_select(__a_unused struct sched *s,
 198                 struct task *t)
 199 {
 200         struct writer_node *wn = container_of(t, struct writer_node, task);
 201         struct private_alsa_write_data *pad = wn->private_data;
 202         struct btr_node *btrn = wn->btrn;
 203         char *data;
 204         size_t bytes;
 205         snd_pcm_sframes_t frames;
 206         int ret;
 207
 208 again:
 209         t->error = 0;
 210         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 211         if (ret == 0)
 212                 return;
 213         btr_merge(btrn, wn->min_iqs);
 214         bytes = btr_next_buffer(btrn, &data);
 215         if (ret < 0 || bytes < wn->min_iqs) { /* eof */
 216                 assert(btr_no_parent(btrn));
 217                 ret = -E_WRITE_COMMON_EOF;
 218                 if (!pad)
 219                         goto err;
 220                 /* wait until pending frames are played */
 221                 if (pad->drain_barrier.tv_sec == 0) {
 222                         PARA_DEBUG_LOG("waiting for device to drain\n");
 223                         tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
 224                                 &pad->drain_barrier);
 225                         return;
 226                 }
 227                 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
 228                         goto err;
 229                 return;
 230         }
 231         if (!pad) {
 232                 int32_t val;
 233
 234                 if (bytes == 0) /* no data available */
 235                         return;
 236                 pad = para_calloc(sizeof(*pad));
 237                 get_btr_sample_rate(btrn, &val);
 238                 pad->sample_rate = val;
 239                 get_btr_channels(btrn, &val);
 240                 pad->channels = val;
 241                 get_btr_sample_format(btrn, &val);
 242                 pad->sample_format = get_alsa_pcm_format(val);
 243
 244                 PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels,
 245                         pad->sample_rate);
 246                 ret = alsa_init(pad, wn->conf);
 247                 if (ret < 0) {
 248                         free(pad);
 249                         goto err;
 250                 }
 251                 wn->private_data = pad;
 252                 wn->min_iqs = pad->bytes_per_frame;
 253                 goto again;
 254         }
 255         frames = bytes / pad->bytes_per_frame;
 256         frames = snd_pcm_writei(pad->handle, data, frames);
 257         if (frames >= 0) {
 258                 btr_consume(btrn, frames * pad->bytes_per_frame);
 259                 goto again;
 260         }
 261         if (frames == -EPIPE) {
 262                 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
 263                 snd_pcm_prepare(pad->handle);
 264                 return;
 265         }
 266         if (frames == -EAGAIN)
 267                 return;
 268         PARA_WARNING_LOG("%s\n", snd_strerror(-frames));
 269         ret = -E_ALSA_WRITE;
 270 err:
 271         assert(ret < 0);
 272         btr_remove_node(btrn);
 273         t->error = ret;
 274 }
 275
 276 __malloc static void *alsa_parse_config_or_die(const char *options)
 277 {
 278         struct alsa_write_args_info *conf = para_calloc(sizeof(*conf));
 279
 280         PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
 281         /* exits on errors */
 282         alsa_cmdline_parser_string(options, conf, "alsa_write");
 283         return conf;
 284 }
 285
 286 static void alsa_free_config(void *conf)
 287 {
 288         alsa_cmdline_parser_free(conf);
 289 }
 290
 291 /**
 292  * The init function of the alsa writer.
 293  *
 294  * \param w Pointer to the writer to initialize.
 295  *
 296  * \sa struct \ref writer.
 297  */
 298 void alsa_write_init(struct writer *w)
 299 {
 300         struct alsa_write_args_info dummy;
 301
 302         alsa_cmdline_parser_init(&dummy);
 303         w->close = alsa_close;
 304         w->pre_select = alsa_write_pre_select;
 305         w->post_select = alsa_write_post_select;
 306         w->parse_config_or_die = alsa_parse_config_or_die;
 307         w->shutdown = NULL; /* nothing to do */
 308         w->free_config = alsa_free_config;
 309         w->help = (struct ggo_help) {
 310                 .short_help = alsa_write_args_info_help,
 311                 .detailed_help = alsa_write_args_info_detailed_help
 312         };
 313         alsa_cmdline_parser_free(&dummy);
 314 }