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

   1 /*
   2  * This file is part of DisOrder.
   3  * Copyright (C) 2009, 2013 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 Frames of buffer to tolerate inside chosen API */
  45 int uaudio_buffer;
  46
  47 /** @brief Sample size in bytes
  48  *
  49  * NB one sample is a single point sample; up to @c uaudio_channels samples may
  50  * play at the same time through different speakers.  Thus this value is
  51  * independent of @ref uaudio_channels.
  52  */
  53 size_t uaudio_sample_size;
  54
  55 /** @brief Set a uaudio option */
  56 void uaudio_set(const char *name, const char *value) {
  57   if(!value) {
  58     if(uaudio_options)
  59       hash_remove(uaudio_options, name);
  60     return;
  61   }
  62   if(!uaudio_options)
  63     uaudio_options = hash_new(sizeof(char *));
  64   value = xstrdup(value);
  65   hash_add(uaudio_options, name, &value, HASH_INSERT_OR_REPLACE);
  66 }
  67
  68 /** @brief Get a uaudio option */
  69 char *uaudio_get(const char *name, const char *default_value) {
  70   if(!uaudio_options)
  71     return default_value ? xstrdup(default_value) : 0;
  72   char **valuep = hash_find(uaudio_options, name);
  73   if(!valuep)
  74     return default_value ? xstrdup(default_value) : 0;
  75   return xstrdup(*valuep);
  76 }
  77
  78 /** @brief Set sample format
  79  * @param rate Sample rate in KHz
  80  * @param channels Number of channels (i.e. 2 for stereo)
  81  * @param bits Number of bits per channel (typically 8 or 16)
  82  * @param signed_ True for signed samples, false for unsigned
  83  *
  84  * Sets @ref uaudio_rate, @ref uaudio_channels, @ref uaudio_bits, @ref
  85  * uaudio_signed and @ref uaudio_sample_size.
  86  *
  87  * Currently there is no way to specify non-native endian formats even if the
  88  * underlying API can conveniently handle them.  Actually this would be quite
  89  * convenient for playrtp, so it might be added at some point.
  90  *
  91  * Not all APIs can support all sample formats.  Generally the @c start
  92  * function will do some error checking but some may be deferred to the point
  93  * the device is opened (which might be @c activate).
  94  */
  95 void uaudio_set_format(int rate, int channels, int bits, int signed_) {
  96   uaudio_rate = rate;
  97   uaudio_channels = channels;
  98   uaudio_bits = bits;
  99   uaudio_signed = signed_;
 100   uaudio_sample_size = bits / CHAR_BIT;
 101 }
 102
 103 /** @brief Choose the default audio API by context
 104  * @param apis Table of APIs or a null pointer
 105  * @param context @ref UAUDIO_API_SERVER or @ref UAUDIO_API_CLIENT
 106  * @return Default API or a null pointer
 107  */
 108 const struct uaudio *uaudio_default(const struct uaudio *const *apis,
 109                                     unsigned context) {
 110   if(apis) {
 111     for(int n = 0; apis[n]; ++n)
 112       if(apis[n]->flags & context)
 113         return apis[n];
 114   }
 115   return 0;
 116 }
 117
 118 /*
 119 Local Variables:
 120 c-basic-offset:2
 121 comment-column:40
 122 fill-column:79
 123 indent-tabs-mode:nil
 124 End:
 125 */