alsa_write.c

   1 /* Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
   2
   3 /** \file alsa_write.c paraslash's alsa output plugin */
   4
   5 /*
   6  * Based in parts on aplay.c from the alsa-utils-1.0.8 package,
   7  * Copyright (c) by Jaroslav Kysela <perex@suse.cz>, which is
   8  * based on the vplay program by Michael Beck.
   9  */
  10
  11 #include <regex.h>
  12 #include <sys/types.h>
  13 #include <alsa/asoundlib.h>
  14 #include <lopsub.h>
  15
  16 #include "write_cmd.lsg.h"
  17 #include "para.h"
  18 #include "fd.h"
  19 #include "string.h"
  20 #include "list.h"
  21 #include "sched.h"
  22 #include "buffer_tree.h"
  23 #include "write.h"
  24 #include "error.h"
  25
  26 /** Data specific to the alsa writer. */
  27 struct private_alsa_write_data {
  28         /** The alsa handle */
  29         snd_pcm_t *handle;
  30         /** Determined and set by alsa_init(). */
  31         int bytes_per_frame;
  32         /*
  33          * If the sample rate is not given at the command line and no wav
  34          * header was detected, the btr exec mechanism is employed to query the
  35          * ancestor buffer tree nodes for this information. In a typical setup
  36          * the decoder passes the sample rate back to the alsa writer.
  37          *
  38          *  \sa \ref btr_exec_up().
  39          */
  40         unsigned sample_rate;
  41         /*
  42          * The sample format (8/16 bit, signed/unsigned, little/big endian) is
  43          * determined in the same way as the \a sample_rate.
  44          */
  45         snd_pcm_format_t sample_format;
  46         /* The number of channels, again determined like \a sample_rate. */
  47         unsigned channels;
  48         /* time until buffer underrun occurs, in milliseconds */
  49         unsigned buffer_time;
  50         struct timeval drain_barrier;
  51         /* File descriptor for select(). */
  52         int poll_fd;
  53 };
  54
  55 static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf)
  56 {
  57         switch (sf) {
  58         case SF_S8: return SND_PCM_FORMAT_S8;
  59         case SF_U8: return SND_PCM_FORMAT_U8;
  60         case SF_S16_LE: return SND_PCM_FORMAT_S16_LE;
  61         case SF_S16_BE: return SND_PCM_FORMAT_S16_BE;
  62         case SF_U16_LE: return SND_PCM_FORMAT_U16_LE;
  63         case SF_U16_BE: return SND_PCM_FORMAT_U16_BE;
  64         default: return SND_PCM_FORMAT_S16_LE;
  65         }
  66 }
  67
  68 /* Install PCM software and hardware configuration. */
  69 static int alsa_init(struct writer_node *wn)
  70 {
  71         struct private_alsa_write_data *pad = wn->private_data;
  72         snd_pcm_hw_params_t *hwparams = NULL;
  73         snd_pcm_sw_params_t *swparams = NULL;
  74         snd_pcm_uframes_t start_threshold, stop_threshold;
  75         snd_pcm_uframes_t buffer_size, period_size;
  76         snd_output_t *output_log;
  77         int ret;
  78         const char *msg, *dev = WRITE_CMD_OPT_STRING_VAL(ALSA, DEVICE, wn->lpr);
  79         unsigned period_time;
  80
  81         PARA_INFO_LOG("opening %s\n", dev);
  82         msg = "unable to open pcm";
  83         ret = snd_pcm_open(&pad->handle, dev, SND_PCM_STREAM_PLAYBACK,
  84                 SND_PCM_NONBLOCK);
  85         if (ret < 0)
  86                 goto fail;
  87         ret = snd_pcm_hw_params_malloc(&hwparams);
  88         assert(ret >= 0);
  89         msg = "Broken alsa configuration";
  90         ret = snd_pcm_hw_params_any(pad->handle, hwparams);
  91         if (ret < 0)
  92                 goto fail;
  93         msg = "access type not available";
  94         ret = snd_pcm_hw_params_set_access(pad->handle, hwparams,
  95                 SND_PCM_ACCESS_RW_INTERLEAVED);
  96         if (ret < 0)
  97                 goto fail;
  98         msg = "sample format not available";
  99         ret = snd_pcm_hw_params_set_format(pad->handle, hwparams,
 100                 pad->sample_format);
 101         if (ret < 0)
 102                 goto fail;
 103         msg = "channels count not available";
 104         ret = snd_pcm_hw_params_set_channels(pad->handle, hwparams,
 105                 pad->channels);
 106         if (ret < 0)
 107                 goto fail;
 108         msg = "could not set sample rate";
 109         ret = snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
 110                 &pad->sample_rate, NULL);
 111         if (ret < 0)
 112                 goto fail;
 113         /* alsa wants microseconds */
 114         pad->buffer_time = 1000U * WRITE_CMD_OPT_UINT32_VAL(ALSA, BUFFER_TIME,
 115                 wn->lpr);
 116         msg = "could not set buffer time";
 117         ret = snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
 118                 &pad->buffer_time, NULL);
 119         if (ret < 0)
 120                 goto fail;
 121         pad->buffer_time /= 1000; /* we prefer milliseconds */
 122         period_time = pad->buffer_time * 250; /* buffer time / 4 */
 123         msg = "could not set period time";
 124         ret = snd_pcm_hw_params_set_period_time_near(pad->handle, hwparams,
 125                 &period_time, NULL);
 126         if (ret < 0)
 127                 goto fail;
 128
 129         msg = "unable to install hw params";
 130         ret = snd_pcm_hw_params(pad->handle, hwparams);
 131         if (ret < 0)
 132                 goto fail;
 133         snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
 134         snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
 135         msg = "period size equals buffer size";
 136         if (period_size == buffer_size)
 137                 goto fail;
 138
 139         /* software parameter setup */
 140         ret = snd_pcm_sw_params_malloc(&swparams);
 141         assert(ret >= 0);
 142         snd_pcm_sw_params_current(pad->handle, swparams);
 143         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 144         if (buffer_size < 1)
 145                 start_threshold = 1;
 146         else
 147                 start_threshold = PARA_MIN(buffer_size,
 148                         (snd_pcm_uframes_t)pad->sample_rate);
 149         msg = "could not set start threshold";
 150         ret = snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 151                 start_threshold);
 152         if (ret < 0)
 153                 goto fail;
 154         stop_threshold = buffer_size;
 155         msg = "could not set stop threshold";
 156         ret = snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 157                 stop_threshold);
 158         if (ret < 0)
 159                 goto fail;
 160         msg = "unable to install sw params";
 161         ret = snd_pcm_sw_params(pad->handle, swparams);
 162         if (ret < 0)
 163                 goto fail;
 164         msg = "unable to determine bytes per frame";
 165         ret = snd_pcm_format_physical_width(pad->sample_format);
 166         if (ret <= 0)
 167                 goto fail;
 168         pad->bytes_per_frame = ret * pad->channels / 8;
 169         msg = "failed to set alsa handle to nonblock mode";
 170         ret = snd_pcm_nonblock(pad->handle, 1);
 171         if (ret < 0)
 172                 goto fail;
 173         ret = snd_output_buffer_open(&output_log);
 174         if (ret == 0) {
 175                 char *buf, *p;
 176                 size_t sz;
 177                 PARA_DEBUG_LOG("dumping alsa configuration\n");
 178                 snd_pcm_dump(pad->handle, output_log);
 179                 snd_pcm_hw_params_dump(hwparams, output_log);
 180                 sz = snd_output_buffer_string(output_log, &buf);
 181                 for (p = buf; p < buf + sz;) {
 182                         char *q = memchr(p, '\n', buf + sz - p);
 183                         if (!q)
 184                                 break;
 185                         *q = '\0';
 186                         PARA_DEBUG_LOG("%s\n", p);
 187                         p = q + 1;
 188                 }
 189                 snd_output_close(output_log);
 190         }
 191         ret = 1;
 192         goto out;
 193 fail:
 194         if (ret < 0)
 195                 PARA_ERROR_LOG("%s: %s\n", msg, snd_strerror(-ret));
 196         else
 197                 PARA_ERROR_LOG("%s\n", msg);
 198         ret = -E_ALSA;
 199 out:
 200         snd_pcm_hw_params_free(hwparams);
 201         snd_pcm_sw_params_free(swparams);
 202         return ret;
 203 }
 204
 205 static void alsa_write_pre_select(struct sched *s, void *context)
 206 {
 207         struct pollfd pfd;
 208         struct writer_node *wn = context;
 209         struct private_alsa_write_data *pad = wn->private_data;
 210         int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
 211
 212         if (pad)
 213                 pad->poll_fd = -1;
 214         if (ret == 0)
 215                 return;
 216         if (!pad) {
 217                 sched_min_delay(s);
 218                 return;
 219         }
 220         if (ret < 0) {
 221                 sched_request_barrier_or_min_delay(&pad->drain_barrier, s);
 222                 return;
 223         }
 224         /* wait at most 50% of the buffer time */
 225         sched_request_timeout_ms(pad->buffer_time / 2, s);
 226         ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1);
 227         if (ret < 0) {
 228                 PARA_ERROR_LOG("could not get alsa poll fd: %s\n",
 229                         snd_strerror(-ret));
 230                 return;
 231         }
 232         pad->poll_fd = pfd.fd;
 233         para_fd_set(pfd.fd, &s->rfds, &s->max_fileno);
 234 }
 235
 236 static void alsa_close(struct writer_node *wn)
 237 {
 238         struct private_alsa_write_data *pad = wn->private_data;
 239         PARA_INFO_LOG("closing writer node %p\n", wn);
 240
 241         if (!pad)
 242                 return;
 243         /*
 244          * It's OK to have a blocking operation here because we already made
 245          * sure that the PCM output buffer is (nearly) empty.
 246          */
 247         snd_pcm_nonblock(pad->handle, 0);
 248         snd_pcm_drain(pad->handle);
 249         snd_pcm_close(pad->handle);
 250         snd_config_update_free_global();
 251         free(pad);
 252 }
 253
 254 static int alsa_write_post_select(__a_unused struct sched *s, void *context)
 255 {
 256         struct writer_node *wn = context;
 257         struct private_alsa_write_data *pad = wn->private_data;
 258         struct btr_node *btrn = wn->btrn;
 259         char *data;
 260         size_t bytes;
 261         snd_pcm_sframes_t frames;
 262         int ret;
 263
 264         ret = task_get_notification(wn->task);
 265         if (ret < 0)
 266                 goto err;
 267 again:
 268         ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
 269         if (ret == 0)
 270                 return 0;
 271         btr_merge(btrn, wn->min_iqs);
 272         bytes = btr_next_buffer(btrn, &data);
 273         if (ret < 0 || bytes < wn->min_iqs) { /* eof */
 274                 assert(btr_no_parent(btrn));
 275                 ret = -E_WRITE_COMMON_EOF;
 276                 if (!pad)
 277                         goto err;
 278                 /* wait until pending frames are played */
 279                 if (pad->drain_barrier.tv_sec == 0) {
 280                         PARA_DEBUG_LOG("waiting for device to drain\n");
 281                         tv_add(now, &(struct timeval)EMBRACE(0, 200 * 1000),
 282                                 &pad->drain_barrier);
 283                         return 0;
 284                 }
 285                 if (tv_diff(now, &pad->drain_barrier, NULL) > 0)
 286                         goto err;
 287                 return 0;
 288         }
 289         if (!pad) {
 290                 int32_t val;
 291
 292                 if (bytes == 0) /* no data available */
 293                         return 0;
 294                 pad = wn->private_data = para_calloc(sizeof(*pad));
 295                 get_btr_sample_rate(btrn, &val);
 296                 pad->sample_rate = val;
 297                 get_btr_channels(btrn, &val);
 298                 pad->channels = val;
 299                 get_btr_sample_format(btrn, &val);
 300                 pad->sample_format = get_alsa_pcm_format(val);
 301
 302                 PARA_INFO_LOG("%u channel(s), %uHz\n", pad->channels,
 303                         pad->sample_rate);
 304                 ret = alsa_init(wn);
 305                 if (ret < 0) {
 306                         free(wn->private_data);
 307                         wn->private_data = NULL;
 308                         goto err;
 309                 }
 310                 wn->min_iqs = pad->bytes_per_frame;
 311                 goto again;
 312         }
 313         frames = bytes / pad->bytes_per_frame;
 314         frames = snd_pcm_writei(pad->handle, data, frames);
 315         if (frames == 0 || frames == -EAGAIN) {
 316                 char buf[100];
 317                 if (pad->poll_fd >= 0 && FD_ISSET(pad->poll_fd, &s->rfds))
 318                         if (read(pad->poll_fd, buf, 100))
 319                                 do_nothing;
 320                 return 0;
 321         }
 322         if (frames > 0) {
 323                 btr_consume(btrn, frames * pad->bytes_per_frame);
 324                 goto again;
 325         }
 326         if (frames == -EPIPE) {
 327                 PARA_WARNING_LOG("underrun (tried to write %zu bytes)\n", bytes);
 328                 snd_pcm_prepare(pad->handle);
 329                 return 0;
 330         }
 331         PARA_ERROR_LOG("alsa write error: %s\n", snd_strerror(-frames));
 332         ret = -E_ALSA;
 333 err:
 334         assert(ret < 0);
 335         btr_remove_node(&wn->btrn);
 336         return ret;
 337 }
 338
 339 struct writer lsg_write_cmd_com_alsa_user_data = {
 340
 341         .pre_select = alsa_write_pre_select,
 342         .post_select = alsa_write_post_select,
 343         .close = alsa_close,
 344 };