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
  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 "write.h"
  28 #include "alsa_write.cmdline.h"
  29 #include "error.h"
  30
  31 /** always use 16 bit little endian */
  32 #define FORMAT SND_PCM_FORMAT_S16_LE
  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_open(). */
  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         unsigned buffer_frames;
  44         /**
  45          * The samplerate given by command line option or the decoder
  46          * of the writer node group.
  47          */
  48         unsigned samplerate;
  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 };
  55
  56 /* Install PCM software and hardware configuration. */
  57 static int alsa_init(struct private_alsa_write_data *pad,
  58                 struct alsa_write_args_info *conf)
  59 {
  60         snd_pcm_hw_params_t *hwparams;
  61         snd_pcm_sw_params_t *swparams;
  62         snd_pcm_uframes_t buffer_size, start_threshold, stop_threshold;
  63         snd_pcm_uframes_t period_size;
  64         int err;
  65
  66         err = snd_pcm_open(&pad->handle, conf->device_arg,
  67                 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
  68         if (err < 0)
  69                 return -E_PCM_OPEN;
  70
  71         snd_pcm_hw_params_alloca(&hwparams);
  72         snd_pcm_sw_params_alloca(&swparams);
  73         if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
  74                 return -E_BROKEN_CONF;
  75         if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
  76                         SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
  77                 return -E_ACCESS_TYPE;
  78         if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
  79                 return -E_SAMPLE_FORMAT;
  80         if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
  81                         pad->channels) < 0)
  82                 return -E_CHANNEL_COUNT;
  83         if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
  84                         &pad->samplerate, NULL) < 0)
  85                 return -E_SET_RATE;
  86         err = snd_pcm_hw_params_get_buffer_time_max(hwparams,
  87                 &pad->buffer_time, NULL);
  88         if (err < 0 || !pad->buffer_time)
  89                 return -E_GET_BUFFER_TIME;
  90         PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
  91         if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
  92                         &pad->buffer_time, NULL) < 0)
  93                 return -E_SET_BUFFER_TIME;
  94         if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
  95                 return -E_HW_PARAMS;
  96         snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
  97         snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
  98         PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", buffer_size,
  99                 period_size);
 100         if (period_size == buffer_size)
 101                 return -E_BAD_PERIOD;
 102         snd_pcm_sw_params_current(pad->handle, swparams);
 103         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 104         if (buffer_size < 1)
 105                 start_threshold = 1;
 106         else
 107                 start_threshold = PARA_MIN(buffer_size,
 108                         (snd_pcm_uframes_t)pad->samplerate);
 109         if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 110                         start_threshold) < 0)
 111                 return -E_START_THRESHOLD;
 112         stop_threshold = buffer_size;
 113         if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 114                         stop_threshold) < 0)
 115                 return -E_STOP_THRESHOLD;
 116         if (snd_pcm_sw_params(pad->handle, swparams) < 0)
 117                 PARA_WARNING_LOG("unable to install sw params\n");
 118         pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
 119                 * pad->channels / 8;
 120         if (pad->bytes_per_frame <= 0)
 121                 return -E_PHYSICAL_WIDTH;
 122         PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
 123         if (snd_pcm_nonblock(pad->handle, 1))
 124                 PARA_ERROR_LOG("failed to set nonblock mode\n");
 125         pad->buffer_frames = 1000 * pad->buffer_time / pad->samplerate;
 126         PARA_INFO_LOG("max buffered frames: %d\n", pad->buffer_frames);
 127         return 1;
 128 }
 129
 130 /* Open an instance of the alsa writer. */
 131 static int alsa_open(struct writer_node *wn)
 132 {
 133         struct alsa_write_args_info *conf = wn->conf;
 134         struct writer_node_group *wng = wn->wng;
 135         struct private_alsa_write_data *pad = para_calloc(sizeof(*pad));
 136
 137         wn->private_data = pad;
 138         if (!conf->samplerate_given && wng->samplerate)
 139                 pad->samplerate = *wng->samplerate;
 140         else
 141                 pad->samplerate = conf->samplerate_arg;
 142         if (!conf->channels_given && wng->channels)
 143                 pad->channels = *wng->channels;
 144         else
 145                 pad->channels = conf->channels_arg;
 146         PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
 147         return 1;
 148 }
 149
 150 static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
 151 {
 152         struct private_alsa_write_data *pad = wn->private_data;
 153         struct writer_node_group *wng = wn->wng;
 154         struct timeval tv;
 155         snd_pcm_sframes_t avail, underrun;
 156
 157         if (!pad->handle)
 158                 return 1;
 159         if (*wng->loaded - wn->written < pad->bytes_per_frame)
 160                 return 1;
 161         /*
 162          * Data is available to be written to the alsa handle.  Compute number
 163          * of milliseconds until next buffer underrun would occur.
 164          *
 165          * snd_pcm_avail_update() updates the current available count of
 166          * samples for writing.  It is a light method to obtain current stream
 167          * position, because it does not require the user <-> kernel context
 168          * switch, but the value is less accurate, because ring buffer pointers
 169          * are updated in kernel drivers only when an interrupt occurs.
 170          */
 171         avail = snd_pcm_avail_update(pad->handle);
 172         if (avail < 0)
 173                 avail = 0;
 174         underrun = (pad->buffer_frames - avail) * pad->buffer_time
 175                 / pad->buffer_frames / 1000;
 176         if (underrun < 50)
 177                 underrun = 50;
 178         underrun -= 50;
 179         ms2tv(underrun, &tv);
 180         if (tv_diff(&s->timeout, &tv, NULL) > 0)
 181                 s->timeout = tv;
 182         return 1;
 183 }
 184
 185 static void xrun(snd_pcm_t *handle)
 186 {
 187         snd_pcm_status_t *status;
 188         int ret;
 189         struct timeval tv, diff;
 190
 191         snd_pcm_status_alloca(&status);
 192         ret = snd_pcm_status(handle, status);
 193         if (ret < 0)
 194                 return;
 195         if (snd_pcm_status_get_state(status) != SND_PCM_STATE_XRUN)
 196                 return;
 197         snd_pcm_status_get_trigger_tstamp(status, &tv);
 198         tv_diff(now, &tv, &diff);
 199         PARA_WARNING_LOG("underrun: %lums\n", tv2ms(&diff));
 200 }
 201
 202 static int alsa_write_post_select(__a_unused struct sched *s,
 203                 struct writer_node *wn)
 204 {
 205         struct private_alsa_write_data *pad = wn->private_data;
 206         struct writer_node_group *wng = wn->wng;
 207         size_t bytes = *wng->loaded - wn->written;
 208         unsigned char *data = (unsigned char*)*wng->bufp + wn->written;
 209         snd_pcm_sframes_t ret, frames, avail;
 210
 211         if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) {
 212                 wn->written = *wng->loaded;
 213                 return *wng->input_error;
 214         }
 215         if (!bytes) /* no data available */
 216                 return 0;
 217         if (!pad->handle) {
 218                 int err = alsa_init(pad, wn->conf);
 219                 if (err < 0)
 220                         return err;
 221         }
 222         frames = bytes / pad->bytes_per_frame;
 223         if (!frames) /* less than a single frame available */
 224                 return 0;
 225         avail = snd_pcm_avail_update(pad->handle);
 226         if (avail <= 0)
 227                 return 0;
 228         frames = PARA_MIN(frames, avail);
 229         ret = snd_pcm_writei(pad->handle, data, frames);
 230         if (ret >= 0) {
 231                 wn->written += ret * pad->bytes_per_frame;
 232                 return 1;
 233         }
 234         if (ret == -EPIPE) {
 235                 xrun(pad->handle);
 236                 snd_pcm_prepare(pad->handle);
 237                 return 0;
 238         }
 239         PARA_WARNING_LOG("%s\n", snd_strerror(-ret));
 240         if (ret == -EAGAIN)
 241                 return 0;
 242         return -E_ALSA_WRITE;
 243 }
 244
 245 static void alsa_close(struct writer_node *wn)
 246 {
 247         struct private_alsa_write_data *pad = wn->private_data;
 248         PARA_INFO_LOG("closing writer node %p\n", wn);
 249
 250         if (pad->handle) {
 251                 snd_pcm_drain(pad->handle);
 252                 snd_pcm_close(pad->handle);
 253                 snd_config_update_free_global();
 254         }
 255         free(pad);
 256 }
 257
 258 __malloc static void *alsa_parse_config(const char *options)
 259 {
 260         int ret;
 261         struct alsa_write_args_info *conf
 262                 = para_calloc(sizeof(struct alsa_write_args_info));
 263
 264         PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
 265         ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
 266         if (ret)
 267                 goto err_out;
 268         PARA_INFO_LOG("help given: %d\n", conf->help_given);
 269         return conf;
 270 err_out:
 271         free(conf);
 272         return NULL;
 273 }
 274
 275 /**
 276  * the init function of the alsa writer
 277  *
 278  * \param w pointer to the writer to initialize
 279  *
 280  * \sa struct writer
 281  */
 282 void alsa_write_init(struct writer *w)
 283 {
 284         struct alsa_write_args_info dummy;
 285
 286         alsa_cmdline_parser_init(&dummy);
 287         w->open = alsa_open;
 288         w->close = alsa_close;
 289         w->pre_select = alsa_write_pre_select;
 290         w->post_select = alsa_write_post_select;
 291         w->parse_config = alsa_parse_config;
 292         w->shutdown = NULL; /* nothing to do */
 293         w->help = (struct ggo_help) {
 294                 .short_help = alsa_write_args_info_help,
 295                 .detailed_help = alsa_write_args_info_detailed_help
 296         };
 297         alsa_cmdline_parser_free(&dummy);
 298 }