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
  20 #include "para.h"
  21 #include "fd.h"
  22 #include "string.h"
  23 #include "list.h"
  24 #include "sched.h"
  25 #include "ggo.h"
  26 #include "write.h"
  27 #include "alsa_write.cmdline.h"
  28 #include "error.h"
  29
  30 /** always use 16 bit little endian */
  31 #define FORMAT SND_PCM_FORMAT_S16_LE
  32
  33 /** Data specific to the alsa writer. */
  34 struct private_alsa_write_data {
  35         /** The alsa handle */
  36         snd_pcm_t *handle;
  37         /** Determined and set by alsa_open(). */
  38         int bytes_per_frame;
  39         /** The approximate maximum buffer duration in us. */
  40         unsigned buffer_time;
  41         /* Number of frames that fit into the buffer. */
  42         unsigned buffer_frames;
  43         /**
  44          * The samplerate given by command line option or the decoder
  45          * of the writer node group.
  46          */
  47         unsigned samplerate;
  48         /**
  49          * The number of channels, given by command line option or the
  50          * decoder of the writer node group.
  51          */
  52         unsigned channels;
  53 };
  54
  55 /* Install PCM software and hardware configuration. */
  56 static int alsa_init(struct private_alsa_write_data *pad,
  57                 struct alsa_write_args_info *conf)
  58 {
  59         snd_pcm_hw_params_t *hwparams;
  60         snd_pcm_sw_params_t *swparams;
  61         snd_pcm_uframes_t buffer_size, start_threshold, stop_threshold;
  62         snd_pcm_uframes_t period_size;
  63         int err;
  64
  65         err = snd_pcm_open(&pad->handle, conf->device_arg,
  66                 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
  67         if (err < 0)
  68                 return -E_PCM_OPEN;
  69
  70         snd_pcm_hw_params_alloca(&hwparams);
  71         snd_pcm_sw_params_alloca(&swparams);
  72         if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
  73                 return -E_BROKEN_CONF;
  74         if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
  75                         SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
  76                 return -E_ACCESS_TYPE;
  77         if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
  78                 return -E_SAMPLE_FORMAT;
  79         if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
  80                         pad->channels) < 0)
  81                 return -E_CHANNEL_COUNT;
  82         if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
  83                         &pad->samplerate, NULL) < 0)
  84                 return -E_SET_RATE;
  85         err = snd_pcm_hw_params_get_buffer_time_max(hwparams,
  86                 &pad->buffer_time, NULL);
  87         if (err < 0 || !pad->buffer_time)
  88                 return -E_GET_BUFFER_TIME;
  89         PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
  90         if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
  91                         &pad->buffer_time, NULL) < 0)
  92                 return -E_SET_BUFFER_TIME;
  93         if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
  94                 return -E_HW_PARAMS;
  95         snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL);
  96         snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
  97         PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", buffer_size,
  98                 period_size);
  99         if (period_size == buffer_size)
 100                 return -E_BAD_PERIOD;
 101         snd_pcm_sw_params_current(pad->handle, swparams);
 102         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 103         if (buffer_size < 1)
 104                 start_threshold = 1;
 105         else
 106                 start_threshold = PARA_MIN(buffer_size,
 107                         (snd_pcm_uframes_t)pad->samplerate);
 108         if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 109                         start_threshold) < 0)
 110                 return -E_START_THRESHOLD;
 111         stop_threshold = buffer_size;
 112         if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 113                         stop_threshold) < 0)
 114                 return -E_STOP_THRESHOLD;
 115         if (snd_pcm_sw_params(pad->handle, swparams) < 0)
 116                 PARA_WARNING_LOG("unable to install sw params\n");
 117         pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
 118                 * pad->channels / 8;
 119         if (pad->bytes_per_frame <= 0)
 120                 return -E_PHYSICAL_WIDTH;
 121         PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
 122         if (snd_pcm_nonblock(pad->handle, 1))
 123                 PARA_ERROR_LOG("failed to set nonblock mode\n");
 124         pad->buffer_frames = 1000 * pad->buffer_time / pad->samplerate;
 125         PARA_INFO_LOG("max buffered frames: %d\n", pad->buffer_frames);
 126         return 1;
 127 }
 128
 129 /* Open an instance of the alsa writer. */
 130 static int alsa_open(struct writer_node *wn)
 131 {
 132         struct alsa_write_args_info *conf = wn->conf;
 133         struct writer_node_group *wng = wn->wng;
 134         struct private_alsa_write_data *pad = para_calloc(sizeof(*pad));
 135
 136         wn->private_data = pad;
 137         if (!conf->samplerate_given && wng->samplerate)
 138                 pad->samplerate = *wng->samplerate;
 139         else
 140                 pad->samplerate = conf->samplerate_arg;
 141         if (!conf->channels_given && wng->channels)
 142                 pad->channels = *wng->channels;
 143         else
 144                 pad->channels = conf->channels_arg;
 145         PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
 146         return 1;
 147 }
 148
 149 static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
 150 {
 151         struct private_alsa_write_data *pad = wn->private_data;
 152         struct writer_node_group *wng = wn->wng;
 153         struct timeval tv;
 154         snd_pcm_sframes_t avail, underrun;
 155
 156         if (!pad->handle)
 157                 return 1;
 158         if (*wng->loaded - wn->written < pad->bytes_per_frame)
 159                 return 1;
 160         /*
 161          * Data is available to be written to the alsa handle.  Compute number
 162          * of milliseconds until next buffer underrun would occur.
 163          *
 164          * snd_pcm_avail_update() updates the current available count of
 165          * samples for writing.  It is a light method to obtain current stream
 166          * position, because it does not require the user <-> kernel context
 167          * switch, but the value is less accurate, because ring buffer pointers
 168          * are updated in kernel drivers only when an interrupt occurs.
 169          */
 170         avail = snd_pcm_avail_update(pad->handle);
 171         if (avail < 0)
 172                 avail = 0;
 173         underrun = (pad->buffer_frames - avail) * pad->buffer_time
 174                 / pad->buffer_frames / 1000;
 175         if (underrun < 50)
 176                 underrun = 50;
 177         underrun -= 50;
 178         ms2tv(underrun, &tv);
 179         if (tv_diff(&s->timeout, &tv, NULL) > 0)
 180                 s->timeout = tv;
 181         return 1;
 182 }
 183
 184 static int alsa_write_post_select(__a_unused struct sched *s,
 185                 struct writer_node *wn)
 186 {
 187         struct private_alsa_write_data *pad = wn->private_data;
 188         struct writer_node_group *wng = wn->wng;
 189         size_t bytes = *wng->loaded - wn->written;
 190         unsigned char *data = (unsigned char*)*wng->bufp + wn->written;
 191         snd_pcm_sframes_t ret, frames, avail;
 192
 193         if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) {
 194                 wn->written = *wng->loaded;
 195                 return *wng->input_error;
 196         }
 197         if (!bytes) /* no data available */
 198                 return 0;
 199         if (!pad->handle) {
 200                 int err = alsa_init(pad, wn->conf);
 201                 if (err < 0)
 202                         return err;
 203         }
 204         frames = bytes / pad->bytes_per_frame;
 205         if (!frames) /* less than a single frame available */
 206                 return 0;
 207         avail = snd_pcm_avail_update(pad->handle);
 208         if (avail <= 0)
 209                 return 0;
 210         frames = PARA_MIN(frames, avail);
 211         ret = snd_pcm_writei(pad->handle, data, frames);
 212         if (ret >= 0) {
 213                 wn->written += ret * pad->bytes_per_frame;
 214                 return 1;
 215         }
 216         PARA_WARNING_LOG("%s\n", snd_strerror(-ret));
 217         if (ret == -EPIPE) {
 218                 snd_pcm_prepare(pad->handle);
 219                 return 0;
 220         }
 221         if (ret == -EAGAIN)
 222                 return 0;
 223         return -E_ALSA_WRITE;
 224 }
 225
 226 static void alsa_close(struct writer_node *wn)
 227 {
 228         struct private_alsa_write_data *pad = wn->private_data;
 229         PARA_INFO_LOG("closing writer node %p\n", wn);
 230
 231         if (pad->handle) {
 232                 snd_pcm_drain(pad->handle);
 233                 snd_pcm_close(pad->handle);
 234                 snd_config_update_free_global();
 235         }
 236         free(pad);
 237 }
 238
 239 __malloc static void *alsa_parse_config(const char *options)
 240 {
 241         int ret;
 242         struct alsa_write_args_info *conf
 243                 = para_calloc(sizeof(struct alsa_write_args_info));
 244
 245         PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
 246         ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
 247         if (ret)
 248                 goto err_out;
 249         PARA_INFO_LOG("help given: %d\n", conf->help_given);
 250         return conf;
 251 err_out:
 252         free(conf);
 253         return NULL;
 254 }
 255
 256 /**
 257  * the init function of the alsa writer
 258  *
 259  * \param w pointer to the writer to initialize
 260  *
 261  * \sa struct writer
 262  */
 263 void alsa_write_init(struct writer *w)
 264 {
 265         struct alsa_write_args_info dummy;
 266
 267         alsa_cmdline_parser_init(&dummy);
 268         w->open = alsa_open;
 269         w->close = alsa_close;
 270         w->pre_select = alsa_write_pre_select;
 271         w->post_select = alsa_write_post_select;
 272         w->parse_config = alsa_parse_config;
 273         w->shutdown = NULL; /* nothing to do */
 274         w->help = (struct ggo_help) {
 275                 .short_help = alsa_write_args_info_help,
 276                 .detailed_help = alsa_write_args_info_detailed_help
 277         };
 278         alsa_cmdline_parser_free(&dummy);
 279 }