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
  28 /** @brief Options for chosen uaudio API */
  29 static hash *uaudio_options;
  30
  31 /** @brief Sample rate (Hz) */
  32 int uaudio_rate;
  33
  34 /** @brief Bits per channel */
  35 int uaudio_bits;
  36
  37 /** @brief Number of channels */
  38 int uaudio_channels;
  39
  40 /** @brief Whether samples are signed or unsigned */
  41 int uaudio_signed;
  42
  43 /** @brief Sample size in bytes
  44  *
  45  * NB one sample is a single point sample; up to @c uaudio_channels samples may
  46  * play at the same time through different speakers.  Thus this value is
  47  * independent of @ref uaudio_channels.
  48  */
  49 size_t uaudio_sample_size;
  50
  51 /** @brief Set a uaudio option */
  52 void uaudio_set(const char *name, const char *value) {
  53   if(!uaudio_options)
  54     uaudio_options = hash_new(sizeof(char *));
  55   value = xstrdup(value);
  56   hash_add(uaudio_options, name, &value, HASH_INSERT_OR_REPLACE);
  57 }
  58
  59 /** @brief Set a uaudio option */
  60 char *uaudio_get(const char *name) {
  61   const char *value = (uaudio_options ?
  62                        *(char **)hash_find(uaudio_options, name)
  63                        : NULL);
  64   return value ? xstrdup(value) : NULL;
  65 }
  66
  67 /** @brief Set sample format
  68  * @param rate Sample rate in KHz
  69  * @param channels Number of channels (i.e. 2 for stereo)
  70  * @param bits Number of bits per channel (typically 8 or 16)
  71  * @param signed_ True for signed samples, false for unsigned
  72  *
  73  * Sets @ref uaudio_rate, @ref uaudio_channels, @ref uaudio_bits, @ref
  74  * uaudio_signed and @ref uaudio_sample_size.
  75  *
  76  * Currently there is no way to specify non-native endian formats even if the
  77  * underlying API can conveniently handle them.  Actually this would be quite
  78  * convenient for playrtp, so it might be added at some point.
  79  *
  80  * Not all APIs can support all sample formats.  Generally the @c start
  81  * function will do some error checking but some may be deferred to the point
  82  * the device is opened (which might be @c activate).
  83  */
  84 void uaudio_set_format(int rate, int channels, int bits, int signed_) {
  85   uaudio_rate = rate;
  86   uaudio_channels = channels;
  87   uaudio_bits = bits;
  88   uaudio_signed = signed_;
  89   uaudio_sample_size = bits / CHAR_BIT;
  90 }
  91
  92 /*
  93 Local Variables:
  94 c-basic-offset:2
  95 comment-column:40
  96 fill-column:79
  97 indent-tabs-mode:nil
  98 End:
  99 */