alsa_writer.c

   1 /*
   2  * Copyright (C) 2005-2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18
  19 /** \file alsa_writer.c paraslash's alsa output plugin */
  20
  21 /*
  22  * Based in parts on aplay.c from the alsa-utils-1.0.8 package,
  23  * Copyright (c) by Jaroslav Kysela <perex@suse.cz>, which is
  24  * based on the vplay program by Michael Beck.
  25  */
  26
  27 #include "para.h"
  28 #include "fd.h"
  29 #include "string.h"
  30 #include "write.h"
  31
  32 #include <alsa/asoundlib.h>
  33
  34 #include "write.cmdline.h"
  35 #include "error.h"
  36
  37 extern struct gengetopt_args_info conf;
  38
  39 #define FORMAT SND_PCM_FORMAT_S16_LE
  40
  41 /** data specific to the alsa writer */
  42 struct private_alsa_data {
  43         snd_pcm_t *handle;
  44         size_t bytes_per_frame;
  45 };
  46
  47 /*
  48  * open and prepare the PCM handle for writing
  49  *
  50  * Install PCM software and hardware configuration. Exit on errors.
  51  */
  52 static int alsa_open(struct writer_node *w)
  53 {
  54         snd_pcm_hw_params_t *hwparams;
  55         snd_pcm_sw_params_t *swparams;
  56         snd_pcm_uframes_t buffer_size, xfer_align, start_threshold,
  57                 stop_threshold;
  58         unsigned buffer_time = 0;
  59         int err;
  60         snd_pcm_info_t *info;
  61         snd_output_t *log;
  62         snd_pcm_uframes_t period_size;
  63         struct private_alsa_data *pad = para_malloc(sizeof(struct private_alsa_data));
  64         w->private_data = pad;
  65
  66         snd_pcm_info_alloca(&info);
  67         if (snd_output_stdio_attach(&log, stderr, 0) < 0)
  68                 return -E_ALSA_LOG;
  69         err = snd_pcm_open(&pad->handle, conf.device_arg,
  70                 SND_PCM_STREAM_PLAYBACK, 0);
  71         if (err < 0)
  72                 return -E_PCM_OPEN;
  73         if ((err = snd_pcm_info(pad->handle, info)) < 0)
  74                 return -E_SND_PCM_INFO;
  75
  76         snd_pcm_hw_params_alloca(&hwparams);
  77         snd_pcm_sw_params_alloca(&swparams);
  78         if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
  79                 return -E_BROKEN_CONF;
  80         if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
  81                         SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
  82                 return -E_ACCESS_TYPE;
  83         if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
  84                 return -E_SAMPLE_FORMAT;
  85         if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
  86                         conf.channels_arg) < 0)
  87                 return -E_CHANNEL_COUNT;
  88         if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
  89                         (unsigned int*) &conf.sample_rate_arg, 0) < 0)
  90                 return -E_SET_RATE;
  91         err = snd_pcm_hw_params_get_buffer_time_max(hwparams, &buffer_time, 0);
  92         if (err < 0 || !buffer_time)
  93                 return -E_GET_BUFFER_TIME;
  94         PARA_DEBUG_LOG("buffer time: %d\n", buffer_time);
  95         if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
  96                         &buffer_time, 0) < 0)
  97                 return -E_SET_BUFFER_TIME;
  98         if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
  99                 return -E_HW_PARAMS;
 100         snd_pcm_hw_params_get_period_size(hwparams, &period_size, 0);
 101         snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
 102         PARA_DEBUG_LOG("buffer size: %lu, period_size: %lu\n", buffer_size,
 103                 period_size);
 104         if (period_size == buffer_size)
 105                 return -E_BAD_PERIOD;
 106         snd_pcm_sw_params_current(pad->handle, swparams);
 107         err = snd_pcm_sw_params_get_xfer_align(swparams, &xfer_align);
 108         if (err < 0 || !xfer_align)
 109                 return -E_GET_XFER;
 110         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 111         /* round to closest transfer boundary */
 112         start_threshold = (buffer_size / xfer_align) * xfer_align;
 113         if (start_threshold < 1)
 114                 start_threshold = 1;
 115         if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 116                         start_threshold) < 0)
 117                 return -E_START_THRESHOLD;
 118         stop_threshold = buffer_size;
 119         if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 120                         stop_threshold) < 0)
 121                 return -E_STOP_THRESHOLD;
 122         if (snd_pcm_sw_params_set_xfer_align(pad->handle, swparams,
 123                         xfer_align) < 0)
 124                 return -E_SET_XFER;
 125         if (snd_pcm_sw_params(pad->handle, swparams) < 0)
 126                 return -E_SW_PARAMS;
 127         pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
 128                 * conf.channels_arg / 8;
 129         return period_size * pad->bytes_per_frame;
 130 }
 131
 132 /**
 133  * push out pcm frames
 134  * \param data pointer do data to be written
 135  * \param nbytes number of bytes (not frames)
 136  *
 137  * \return Number of bytes written, -E_ALSA_WRITE on errors.
 138  */
 139 static int alsa_write(char *data, size_t nbytes, struct writer_node *wn)
 140 {
 141         struct private_alsa_data *pad = wn->private_data;
 142         size_t frames = nbytes / pad->bytes_per_frame;
 143         unsigned char *d = (unsigned char*)data;
 144         snd_pcm_sframes_t r, result = 0;
 145
 146         while (frames > 0) {
 147                 /* write interleaved frames */
 148                 r = snd_pcm_writei(pad->handle, d, frames);
 149                 if (r < 0)
 150                         PARA_ERROR_LOG("write error: %s\n", snd_strerror(r));
 151                 if (r == -EAGAIN || (r >= 0 && r < frames))
 152                         snd_pcm_wait(pad->handle, 1);
 153                 else if (r == -EPIPE)
 154                         snd_pcm_prepare(pad->handle);
 155                 else if (r < 0)
 156                         return -E_ALSA_WRITE;
 157                 if (r > 0) {
 158                         result += r;
 159                         frames -= r;
 160                         d += r * pad->bytes_per_frame;
 161                 }
 162         }
 163         return result * pad->bytes_per_frame;
 164 }
 165
 166 static void alsa_close(struct writer_node *wn)
 167 {
 168         struct private_alsa_data *pad = wn->private_data;
 169         snd_pcm_drain(pad->handle);
 170         snd_pcm_close(pad->handle);
 171         snd_config_update_free_global();
 172         free(pad);
 173 }
 174
 175 void alsa_writer_init(struct writer *w)
 176 {
 177         w->open = alsa_open;
 178         w->write = alsa_write;
 179         w->close = alsa_close;
 180         w->shutdown = NULL; /* nothing to do */
 181 }