1 /* ------------------------------------------------------------------ 2 * Copyright (C) 1998-2009 PacketVideo 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either 13 * express or implied. 14 * See the License for the specific language governing permissions 15 * and limitations under the License. 16 * ------------------------------------------------------------------- 17 */ 18 /* 19 ------------------------------------------------------------------------------ 20 21 PacketVideo Corp. 22 MP3 Decoder Library 23 24 Filename: pvmp3_get_main_data_size.cpp 25 26 Date: 09/21/2007 27 28 ------------------------------------------------------------------------------ 29 REVISION HISTORY 30 31 32 Description: 33 34 ------------------------------------------------------------------------------ 35 INPUT AND OUTPUT DEFINITIONS 36 37 Input 38 mp3Header *info, pointer to mp3 header info structure 39 tmp3dec_file *pVars 40 contains information that needs to persist 41 between calls to this function, or is too big to 42 be placed on the stack, even though the data is 43 only needed during execution of this function 44 45 Returns 46 47 main data frame size 48 49 ------------------------------------------------------------------------------ 50 FUNCTION DESCRIPTION 51 52 get main data frame size 53 54 ------------------------------------------------------------------------------ 55 REQUIREMENTS 56 57 58 ------------------------------------------------------------------------------ 59 REFERENCES 60 61 [1] ISO MPEG Audio Subgroup Software Simulation Group (1996) 62 ISO 13818-3 MPEG-2 Audio Decoder - Lower Sampling Frequency Extension 63 64 ------------------------------------------------------------------------------ 65 PSEUDO-CODE 66 67 ------------------------------------------------------------------------------ 68 */ 69 70 71 /*---------------------------------------------------------------------------- 72 ; INCLUDES 73 ----------------------------------------------------------------------------*/ 74 75 #include "pvmp3_tables.h" 76 #include "pvmp3_get_main_data_size.h" 77 #include "pv_mp3dec_fxd_op.h" 78 79 80 /*---------------------------------------------------------------------------- 81 ; MACROS 82 ; Define module specific macros here 83 ----------------------------------------------------------------------------*/ 84 85 86 /*---------------------------------------------------------------------------- 87 ; DEFINES 88 ; Include all pre-processor statements here. Include conditional 89 ; compile variables also. 90 ----------------------------------------------------------------------------*/ 91 92 /*---------------------------------------------------------------------------- 93 ; LOCAL FUNCTION DEFINITIONS 94 ; Function Prototype declaration 95 ----------------------------------------------------------------------------*/ 96 97 /*---------------------------------------------------------------------------- 98 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS 99 ; Variable declaration - defined here and used outside this module 100 ----------------------------------------------------------------------------*/ 101 102 /*---------------------------------------------------------------------------- 103 ; EXTERNAL FUNCTION REFERENCES 104 ; Declare functions defined elsewhere and referenced in this module 105 ----------------------------------------------------------------------------*/ 106 107 /*---------------------------------------------------------------------------- 108 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 109 ; Declare variables used in this module but defined elsewhere 110 ----------------------------------------------------------------------------*/ 111 112 /*---------------------------------------------------------------------------- 113 ; FUNCTION CODE 114 ----------------------------------------------------------------------------*/ 115 116 int32 pvmp3_get_main_data_size(mp3Header *info, 117 tmp3dec_file *pVars) 118 { 119 120 121 int32 numBytes = fxp_mul32_Q28(mp3_bitrate[info->version_x][info->bitrate_index] << 20, 122 inv_sfreq[info->sampling_frequency]); 123 124 125 numBytes >>= (20 - info->version_x); 126 127 /* 128 * Remove the size of the side information from the main data total 129 */ 130 if (info->version_x == MPEG_1) 131 { 132 pVars->predicted_frame_size = numBytes; 133 if (info->mode == MPG_MD_MONO) 134 { 135 numBytes -= 17; 136 } 137 else 138 { 139 numBytes -= 32; 140 } 141 } 142 else 143 { 144 numBytes >>= 1; 145 pVars->predicted_frame_size = numBytes; 146 147 if (info->mode == MPG_MD_MONO) 148 { 149 numBytes -= 9; 150 } 151 else 152 { 153 numBytes -= 17; 154 } 155 } 156 157 if (info->padding) 158 { 159 numBytes++; 160 pVars->predicted_frame_size++; 161 } 162 163 if (info->error_protection) 164 { 165 numBytes -= 6; 166 } 167 else 168 { 169 numBytes -= 4; 170 } 171 172 173 if (numBytes < 0) 174 { 175 numBytes = 0; 176 } 177 178 return(numBytes); 179 } 180 181
