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channels.c
资源名称：NETVIDEO.rar　[点击查看]
上传用户：sun1608
上传日期：2007-02-02
资源大小：6116k
文件大小：5k
源码类别：

流媒体/Mpeg4/MP4

开发平台：

Visual C++

channels.c：源码内容
  1. /*
  2.  * FAAC - Freeware Advanced Audio Coder
  3.  * Copyright (C) 2001 Menno Bakker
  4.  *
  5.  * This library is free software; you can redistribute it and/or
  6.  * modify it under the terms of the GNU Lesser General Public
  7.  * License as published by the Free Software Foundation; either
  8.  * version 2.1 of the License, or (at your option) any later version.
  9.  *
  10.  * This library 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 GNU
  13.  * Lesser General Public License for more details.
  15.  * You should have received a copy of the GNU Lesser General Public
  16.  * License along with this library; if not, write to the Free Software
  17.  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18.  *
  19.  * $Id: channels.c,v 1.3 2001/06/04 23:02:24 wmay Exp $
  20.  */
  22. #include "channels.h"
  23. #include "coder.h"
  24. #include "util.h"
  26. /* If LFE present                                                       */
  27. /*  Num channels       # of SCE's       # of CPE's       #of LFE's      */ 
  28. /*  ============       ==========       ==========       =========      */
  29. /*      1                  1                0               0           */
  30. /*      2                  0                1               0           */
  31. /*      3                  1                1               0           */
  32. /*      4                  1                1               1           */
  33. /*      5                  1                2               0           */
  34. /* For more than 5 channels, use the following elements:                */
  35. /*      2*N                1                2*(N-1)         1           */
  36. /*      2*N+1              1                2*N             0           */
  37. /*                                                                      */
  38. /* Else:                                                                */
  39. /*                                                                      */  
  40. /*  Num channels       # of SCE's       # of CPE's       #of LFE's      */
  41. /*  ============       ==========       ==========       =========      */
  42. /*      1                  1                0               0           */
  43. /*      2                  0                1               0           */
  44. /*      3                  1                1               0           */
  45. /*      4                  2                1               0           */
  46. /*      5                  1                2               0           */
  47. /* For more than 5 channels, use the following elements:                */
  48. /*      2*N                2                2*(N-1)         0           */
  49. /*      2*N+1              1                2*N             0           */
  51. void GetChannelInfo(ChannelInfo *channelInfo, int numChannels, int useLfe)
  52. {
  53. int sceTag = 0;
  54. int lfeTag = 0;
  55. int cpeTag = 0;
  56. int numChannelsLeft = numChannels;
  59. /* First element is sce, except for 2 channel case */
  60. if (numChannelsLeft != 2) {
  61. channelInfo[numChannels-numChannelsLeft].present = 1;
  62. channelInfo[numChannels-numChannelsLeft].tag = sceTag++;
  63. channelInfo[numChannels-numChannelsLeft].cpe = 0;
  64. channelInfo[numChannels-numChannelsLeft].lfe = 0;    
  65. numChannelsLeft--;
  66. }
  68. /* Next elements are cpe's */
  69. while (numChannelsLeft > 1) {
  70. /* Left channel info */
  71. channelInfo[numChannels-numChannelsLeft].present = 1;
  72. channelInfo[numChannels-numChannelsLeft].tag = cpeTag++;
  73. channelInfo[numChannels-numChannelsLeft].cpe = 1;
  74. channelInfo[numChannels-numChannelsLeft].common_window = 0;
  75. channelInfo[numChannels-numChannelsLeft].ch_is_left = 1;
  76. channelInfo[numChannels-numChannelsLeft].paired_ch = numChannels-numChannelsLeft+1;
  77. channelInfo[numChannels-numChannelsLeft].lfe = 0;    
  78. numChannelsLeft--;
  80. /* Right channel info */
  81. channelInfo[numChannels-numChannelsLeft].present = 1;
  82. channelInfo[numChannels-numChannelsLeft].cpe = 1;
  83. channelInfo[numChannels-numChannelsLeft].common_window = 0;
  84. channelInfo[numChannels-numChannelsLeft].ch_is_left = 0;
  85. channelInfo[numChannels-numChannelsLeft].paired_ch = numChannels-numChannelsLeft-1;
  86. channelInfo[numChannels-numChannelsLeft].lfe = 0;
  87. numChannelsLeft--;
  88. }
  90. /* Is there another channel left ? */
  91. if (numChannelsLeft) {
  92. if (useLfe) { 
  93. channelInfo[numChannels-numChannelsLeft].present = 1;
  94. channelInfo[numChannels-numChannelsLeft].tag = lfeTag++;
  95. channelInfo[numChannels-numChannelsLeft].cpe = 0;
  96. channelInfo[numChannels-numChannelsLeft].lfe = 1; 
  97. } else {
  98. channelInfo[numChannels-numChannelsLeft].present = 1;
  99. channelInfo[numChannels-numChannelsLeft].tag = sceTag++;
  100. channelInfo[numChannels-numChannelsLeft].cpe = 0;
  101. channelInfo[numChannels-numChannelsLeft].lfe = 0;
  102. }
  103. numChannelsLeft--;
  104. }
  105. }