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
pvmp3_get_main_data_size(mp3Header * info,tmp3dec_file * pVars)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