mdw@git.distorted.org.uk Git - disorder/blob - lib/uaudio.c

   1 /*
   2  * This file is part of DisOrder.
   3  * Copyright (C) 2009 Richard Kettlewell
   4  *
   5  * This program is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation, either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 /** @file lib/uaudio.c
  20  * @brief Uniform audio interface
  21  */
  22
  23 #include "common.h"
  24 #include "uaudio.h"
  25 #include "hash.h"
  26 #include "mem.h"
  27 #include "log.h"
  28
  29 /** @brief Options for chosen uaudio API */
  30 static hash *uaudio_options;
  31
  32 /** @brief Sample rate (Hz) */
  33 int uaudio_rate;
  34
  35 /** @brief Bits per channel */
  36 int uaudio_bits;
  37
  38 /** @brief Number of channels */
  39 int uaudio_channels;
  40
  41 /** @brief Whether samples are signed or unsigned */
  42 int uaudio_signed;
  43
  44 /** @brief Sample size in bytes
  45  *
  46  * NB one sample is a single point sample; up to @c uaudio_channels samples may
  47  * play at the same time through different speakers.  Thus this value is
  48  * independent of @ref uaudio_channels.
  49  */
  50 size_t uaudio_sample_size;
  51
  52 /** @brief Set a uaudio option */
  53 void uaudio_set(const char *name, const char *value) {
  54   if(!value) {
  55     if(uaudio_options)
  56       hash_remove(uaudio_options, name);
  57     return;
  58   }
  59   if(!uaudio_options)
  60     uaudio_options = hash_new(sizeof(char *));
  61   value = xstrdup(value);
  62   hash_add(uaudio_options, name, &value, HASH_INSERT_OR_REPLACE);
  63 }
  64
  65 /** @brief Get a uaudio option */
  66 char *uaudio_get(const char *name, const char *default_value) {
  67   if(!uaudio_options)
  68     return default_value ? xstrdup(default_value) : 0;
  69   char **valuep = hash_find(uaudio_options, name);
  70   if(!valuep)
  71     return default_value ? xstrdup(default_value) : 0;
  72   return xstrdup(*valuep);
  73 }
  74
  75 /** @brief Set sample format
  76  * @param rate Sample rate in KHz
  77  * @param channels Number of channels (i.e. 2 for stereo)
  78  * @param bits Number of bits per channel (typically 8 or 16)
  79  * @param signed_ True for signed samples, false for unsigned
  80  *
  81  * Sets @ref uaudio_rate, @ref uaudio_channels, @ref uaudio_bits, @ref
  82  * uaudio_signed and @ref uaudio_sample_size.
  83  *
  84  * Currently there is no way to specify non-native endian formats even if the
  85  * underlying API can conveniently handle them.  Actually this would be quite
  86  * convenient for playrtp, so it might be added at some point.
  87  *
  88  * Not all APIs can support all sample formats.  Generally the @c start
  89  * function will do some error checking but some may be deferred to the point
  90  * the device is opened (which might be @c activate).
  91  */
  92 void uaudio_set_format(int rate, int channels, int bits, int signed_) {
  93   uaudio_rate = rate;
  94   uaudio_channels = channels;
  95   uaudio_bits = bits;
  96   uaudio_signed = signed_;
  97   uaudio_sample_size = bits / CHAR_BIT;
  98 }
  99
 100 /*
 101 Local Variables:
 102 c-basic-offset:2
 103 comment-column:40
 104 fill-column:79
 105 indent-tabs-mode:nil
 106 End:
 107 */