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 <sys/types.h>
  16 #include <dirent.h>
  17 #include <alsa/asoundlib.h>
  18
  19 #include "para.h"
  20 #include "fd.h"
  21 #include "string.h"
  22 #include "list.h"
  23 #include "sched.h"
  24 #include "ggo.h"
  25 #include "write.h"
  26 #include "alsa_write.cmdline.h"
  27 #include "error.h"
  28
  29 /** always use 16 bit little endian */
  30 #define FORMAT SND_PCM_FORMAT_S16_LE
  31
  32 /** Data specific to the alsa writer. */
  33 struct private_alsa_write_data {
  34         /** The alsa handle */
  35         snd_pcm_t *handle;
  36         /** Determined and set by alsa_open(). */
  37         int bytes_per_frame;
  38         /** The approximate maximum buffer duration in us. */
  39         unsigned buffer_time;
  40         /* Number of frames that fit into the buffer. */
  41         unsigned buffer_frames;
  42         /**
  43          * The samplerate given by command line option or the decoder
  44          * of the writer node group.
  45          */
  46         unsigned samplerate;
  47         /**
  48          * The number of channels, given by command line option or the
  49          * decoder of the writer node group.
  50          */
  51         unsigned channels;
  52 };
  53
  54 /* Install PCM software and hardware configuration. */
  55 static int alsa_init(struct private_alsa_write_data *pad,
  56                 struct alsa_write_args_info *conf)
  57 {
  58         snd_pcm_hw_params_t *hwparams;
  59         snd_pcm_sw_params_t *swparams;
  60         snd_pcm_uframes_t buffer_size, start_threshold, stop_threshold;
  61         snd_pcm_uframes_t period_size;
  62         int err;
  63
  64         err = snd_pcm_open(&pad->handle, conf->device_arg,
  65                 SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
  66         if (err < 0)
  67                 return -E_PCM_OPEN;
  68
  69         snd_pcm_hw_params_alloca(&hwparams);
  70         snd_pcm_sw_params_alloca(&swparams);
  71         if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
  72                 return -E_BROKEN_CONF;
  73         if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
  74                         SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
  75                 return -E_ACCESS_TYPE;
  76         if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
  77                 return -E_SAMPLE_FORMAT;
  78         if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
  79                         pad->channels) < 0)
  80                 return -E_CHANNEL_COUNT;
  81         if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
  82                         &pad->samplerate, 0) < 0)
  83                 return -E_SET_RATE;
  84         err = snd_pcm_hw_params_get_buffer_time_max(hwparams, &pad->buffer_time, 0);
  85         if (err < 0 || !pad->buffer_time)
  86                 return -E_GET_BUFFER_TIME;
  87         PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time);
  88         if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
  89                         &pad->buffer_time, 0) < 0)
  90                 return -E_SET_BUFFER_TIME;
  91         if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
  92                 return -E_HW_PARAMS;
  93         snd_pcm_hw_params_get_period_size(hwparams, &period_size, 0);
  94         snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
  95         PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", buffer_size,
  96                 period_size);
  97         if (period_size == buffer_size)
  98                 return -E_BAD_PERIOD;
  99         snd_pcm_sw_params_current(pad->handle, swparams);
 100         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 101         if (buffer_size < 1)
 102                 start_threshold = 1;
 103         else
 104                 start_threshold = PARA_MIN(buffer_size,
 105                         (snd_pcm_uframes_t)pad->samplerate);
 106         if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 107                         start_threshold) < 0)
 108                 return -E_START_THRESHOLD;
 109         stop_threshold = buffer_size;
 110         if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 111                         stop_threshold) < 0)
 112                 return -E_STOP_THRESHOLD;
 113         if (snd_pcm_sw_params(pad->handle, swparams) < 0)
 114                 PARA_WARNING_LOG("unable to install sw params\n");
 115         pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
 116                 * pad->channels / 8;
 117         if (pad->bytes_per_frame <= 0)
 118                 return -E_PHYSICAL_WIDTH;
 119         PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
 120         if (snd_pcm_nonblock(pad->handle, 1))
 121                 PARA_ERROR_LOG("failed to set nonblock mode\n");
 122         pad->buffer_frames = 1000 * pad->buffer_time / pad->samplerate;
 123         PARA_INFO_LOG("max buffered frames: %d\n", pad->buffer_frames);
 124         return 1;
 125 }
 126
 127 /* Open an instance of the alsa writer. */
 128 static int alsa_open(struct writer_node *wn)
 129 {
 130         struct alsa_write_args_info *conf = wn->conf;
 131         struct writer_node_group *wng = wn->wng;
 132         struct private_alsa_write_data *pad = para_calloc(sizeof(*pad));
 133
 134         wn->private_data = pad;
 135         if (!conf->samplerate_given && wng->samplerate)
 136                 pad->samplerate = *wng->samplerate;
 137         else
 138                 pad->samplerate = conf->samplerate_arg;
 139         if (!conf->channels_given && wng->channels)
 140                 pad->channels = *wng->channels;
 141         else
 142                 pad->channels = conf->channels_arg;
 143         PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate);
 144         return 1;
 145 }
 146
 147 static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
 148 {
 149         struct private_alsa_write_data *pad = wn->private_data;
 150         struct writer_node_group *wng = wn->wng;
 151         struct timeval tv;
 152         snd_pcm_sframes_t avail, underrun;
 153
 154         if (!pad->handle)
 155                 return 1;
 156         if (*wng->loaded - wn->written < pad->bytes_per_frame)
 157                 return 1;
 158         /*
 159          * Data is available to be written to the alsa handle.  Compute number
 160          * of milliseconds until next buffer underrun would occur.
 161          *
 162          * snd_pcm_avail_update() updates the current available count of
 163          * samples for writing.  It is a light method to obtain current stream
 164          * position, because it does not require the user <-> kernel context
 165          * switch, but the value is less accurate, because ring buffer pointers
 166          * are updated in kernel drivers only when an interrupt occurs.
 167          */
 168         avail = snd_pcm_avail_update(pad->handle);
 169         if (avail < 0)
 170                 avail = 0;
 171         underrun = (pad->buffer_frames - avail) * pad->buffer_time
 172                 / pad->buffer_frames / 1000;
 173         if (underrun < 50)
 174                 underrun = 50;
 175         underrun -= 50;
 176         ms2tv(underrun, &tv);
 177         if (tv_diff(&s->timeout, &tv, NULL) > 0)
 178                 s->timeout = tv;
 179         return 1;
 180 }
 181
 182 static int alsa_write_post_select(__a_unused struct sched *s,
 183                 struct writer_node *wn)
 184 {
 185         struct private_alsa_write_data *pad = wn->private_data;
 186         struct writer_node_group *wng = wn->wng;
 187         size_t bytes = *wng->loaded - wn->written;
 188         unsigned char *data = (unsigned char*)*wng->bufp + wn->written;
 189         snd_pcm_sframes_t ret, frames, avail;
 190
 191         if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) {
 192                 wn->written = *wng->loaded;
 193                 return *wng->input_error;
 194         }
 195         if (!bytes) /* no data available */
 196                 return 0;
 197         if (!pad->handle) {
 198                 int err = alsa_init(pad, wn->conf);
 199                 if (err < 0)
 200                         return err;
 201         }
 202         frames = bytes / pad->bytes_per_frame;
 203         if (!frames) /* less than a single frame available */
 204                 return 0;
 205         avail = snd_pcm_avail_update(pad->handle);
 206         if (avail <= 0)
 207                 return 0;
 208         frames = PARA_MIN(frames, avail);
 209         ret = snd_pcm_writei(pad->handle, data, frames);
 210         if (ret >= 0) {
 211                 wn->written += ret * pad->bytes_per_frame;
 212                 return 1;
 213         }
 214         PARA_WARNING_LOG("%s\n", snd_strerror(-ret));
 215         if (ret == -EPIPE) {
 216                 snd_pcm_prepare(pad->handle);
 217                 return 0;
 218         }
 219         if (ret == -EAGAIN)
 220                 return 0;
 221         return -E_ALSA_WRITE;
 222 }
 223
 224 static void alsa_close(struct writer_node *wn)
 225 {
 226         struct private_alsa_write_data *pad = wn->private_data;
 227         PARA_INFO_LOG("closing writer node %p\n", wn);
 228
 229         if (pad->handle) {
 230                 snd_pcm_drain(pad->handle);
 231                 snd_pcm_close(pad->handle);
 232                 snd_config_update_free_global();
 233         }
 234         free(pad);
 235 }
 236
 237 __malloc static void *alsa_parse_config(const char *options)
 238 {
 239         int ret;
 240         struct alsa_write_args_info *conf
 241                 = para_calloc(sizeof(struct alsa_write_args_info));
 242
 243         PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t"));
 244         ret = alsa_cmdline_parser_string(options, conf, "alsa_write");
 245         if (ret)
 246                 goto err_out;
 247         PARA_INFO_LOG("help given: %d\n", conf->help_given);
 248         return conf;
 249 err_out:
 250         free(conf);
 251         return NULL;
 252 }
 253
 254 /**
 255  * the init function of the alsa writer
 256  *
 257  * \param w pointer to the writer to initialize
 258  *
 259  * \sa struct writer
 260  */
 261 void alsa_write_init(struct writer *w)
 262 {
 263         struct alsa_write_args_info dummy;
 264
 265         alsa_cmdline_parser_init(&dummy);
 266         w->open = alsa_open;
 267         w->close = alsa_close;
 268         w->pre_select = alsa_write_pre_select;
 269         w->post_select = alsa_write_post_select;
 270         w->parse_config = alsa_parse_config;
 271         w->shutdown = NULL; /* nothing to do */
 272         w->help = (struct ggo_help) {
 273                 .short_help = alsa_write_args_info_help,
 274                 .detailed_help = alsa_write_args_info_detailed_help
 275         };
 276         alsa_cmdline_parser_free(&dummy);
 277 }