src/apps/cortex/support/SoundUtils.cpp

   1 /*
   2  * Copyright 1998-1999, Be Incorporated.
   3  * Copyright (c) 1999-2000, Eric Moon.
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions, and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions, and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. The name of the author may not be used to endorse or promote products
  18  *    derived from this software without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR
  21  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  22  * OF TITLE, NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  24  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  25  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  26  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  27  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
  28  * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32
  33 /*******************************************************************************
  34 /
  35 /       File:                   SoundUtils.cpp
  36 /
  37 /   Description:        Utility functions for handling audio data.
  38 /
  39 *******************************************************************************/
  40
  41 #include "SoundUtils.h"
  42
  43 #include <cmath>
  44
  45 // These two conversions seem to pop up all the time in media code.
  46 // I guess it's the curse of microsecond resolution... ;-)
  47 double
  48 us_to_s(bigtime_t usecs)
  49 {
  50         return (usecs / 1000000.0);
  51 }
  52
  53 bigtime_t
  54 s_to_us(double secs)
  55 {
  56         return (bigtime_t) (secs * 1000000.0);
  57 }
  58
  59 int
  60 bytes_per_frame(
  61         const media_raw_audio_format & format)
  62 {
  63         //      The media_raw_audio_format format constants encode the
  64         //      bytes-per-sample value in the low nybble. Having a fixed
  65         //      number of bytes-per-sample, and no inter-sample relationships,
  66         //      is what makes a format "raw".
  67         int bytesPerSample = format.format & 0xf;
  68         return bytesPerSample * format.channel_count;
  69 }
  70
  71 int
  72 frames_per_buffer(
  73         const media_raw_audio_format & format)
  74 {
  75         // This will give us the number of full-sized frames that will fit
  76         // in a buffer. (Remember, integer division automatically rounds
  77         // down.)
  78         int frames = 0;
  79         if (bytes_per_frame(format) > 0) {
  80                 frames = format.buffer_size / bytes_per_frame(format);
  81         }
  82         return frames;
  83 }
  84
  85 bigtime_t
  86 buffer_duration(
  87         const media_raw_audio_format & format)
  88 {
  89         //      Figuring out duration is easy. We take extra precaution to
  90         //      not divide by zero or return irrelevant results.
  91         bigtime_t duration = 0;
  92         if (format.buffer_size > 0 && format.frame_rate > 0 && bytes_per_frame(format) > 0) {
  93                 //      In these kinds of calculations, it's always useful to double-check
  94                 //      the unit conversions. (Anyone remember high school physics?)
  95                 //      bytes/(bytes/frame) / frames/sec
  96                 //      = frames * sec/frames
  97                 //      = secs                            which is what we want.
  98                 duration = s_to_us((format.buffer_size / bytes_per_frame(format)) / format.frame_rate);
  99         }
 100         return duration;
 101 }
 102
 103 bigtime_t
 104 frames_duration(
 105         const media_raw_audio_format & format, int64 num_frames)
 106 {
 107         //      Tells us how long in us it will take to produce num_frames,
 108         //      with the given format.
 109         bigtime_t duration = 0;
 110         if (format.frame_rate > 0) {
 111                 duration = s_to_us(num_frames/format.frame_rate);
 112         }
 113         return duration;
 114 }
 115
 116 int
 117 buffers_for_duration(
 118         const media_raw_audio_format & format, bigtime_t duration)
 119 {
 120         // Double-checking those unit conversions again:
 121         // secs * ( (frames/sec) / (frames/buffer) ) = secs * (buffers/sec) = buffers
 122         int buffers = 0;
 123         if (frames_per_buffer(format) > 0) {
 124                 buffers = (int) ceil(us_to_s(duration)*(format.frame_rate/frames_per_buffer(format)));
 125         }
 126         return buffers;
 127 }
 128
 129 int64
 130 frames_for_duration(
 131         const media_raw_audio_format & format, bigtime_t duration)
 132 {
 133         return (int64) ceil(format.frame_rate*us_to_s(duration));
 134 }