M4_BitStreamParser.h revision 7c9d8018755adf1857571125ba1b3598c96ea506 
1/*
2 * Copyright (C) 2004-2011 NXP Software
3 * Copyright (C) 2011 The Android Open Source Project
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17/**
18 ************************************************************************
19 * @file   M4_BitStreamParser.h
20 * @brief  MPEG-4 File Format bit stream utility
21 * @note   This file contains utility functions used to parse MPEG specific
22 *         data structures.
23 ************************************************************************
24*/
25#ifndef __M4_BITSTREAMPARSER_H__
26#define __M4_BITSTREAMPARSER_H__
27
28#include "M4OSA_Types.h"
29
30/**
31* M4_BitStreamParser_Init.
32*
33* Allocates the context and initializes internal data
34*
35* @param pContext   : A pointer to the context internally used by the package - ALLOCATED BY THE
36*                    FUNCTION (M4OSA_NULL if allocation fails)
37* @param bitStream  : A pointer to the bitstream - must be 32 bits as access are 32 bits
38* @param size        : The size of the bitstream in bytes
39*
40*/
41void M4_BitStreamParser_Init(void** pContext, void* pBitStream, M4OSA_Int32 size);
42
43/**
44 ************************************************************************
45 * @brief    Clean up context
46 * @param    pContext    (IN/OUT)  M4_BitStreamParser context.
47 ************************************************************************
48*/
49void M4_BitStreamParser_CleanUp(void* pContext);
50
51/**
52 ************************************************************************
53 * @brief    Read the next <length> bits in the bitstream.
54 * @note    The function does not update the bitstream pointer.
55 * @param    pContext    (IN/OUT) M4_BitStreamParser context.
56 * @param    length        (IN) The number of bits to extract from the bitstream
57 * @return    the read bits
58 ************************************************************************
59*/
60M4OSA_UInt32 M4_BitStreamParser_ShowBits(void* pContext, M4OSA_Int32 length);
61
62/**
63 ************************************************************************
64 * @brief    Increment the bitstream pointer of <length> bits.
65 * @param    pContext    (IN/OUT) M4_BitStreamParser context.
66 * @param    length        (IN) The number of bit to shift the bitstream
67 ************************************************************************
68*/
69void M4_BitStreamParser_FlushBits(void* pContext, M4OSA_Int32 length);
70
71/**
72 ************************************************************************
73 * @brief    Get a pointer to the current byte pointed by the bitstream pointer.
74 * It does not update the bitstream pointer
75 *
76 * @param pContext   : A pointer to the context internally used by the package
77 * @param length        : The number of bit to extract from the bitstream
78 *
79 * @returns the read bits
80*/
81M4OSA_UInt32 M4_BitStreamParser_GetBits(void* pContext,M4OSA_Int32 bitPos, M4OSA_Int32 length);
82
83/**
84* M4_BitStreamParser_Restart resets the bitstream indexes.
85*
86* @param pContext   : A pointer to the context internally used by the package
87*
88*/
89void M4_BitStreamParser_Restart(void* pContext);
90
91/**
92 ************************************************************************
93 * @brief    Get a pointer to the current byte pointed by the bitstream pointer.
94 * @returns pointer to the current location in the bitstream
95 * @note    It should be used carefully as the pointer is in the bitstream itself
96 *            and no copy is made.
97 * @param    pContext    (IN/OUT)  M4_BitStreamParser context.
98*/
99M4OSA_UInt8*  M4_BitStreamParser_GetCurrentbitStreamPointer(void* pContext);
100
101/**
102* M4_BitStreamParser_GetSize gets the size of the bitstream in bytes
103*
104* @param pContext   : A pointer to the context internally used by the package
105*
106* @returns the size of the bitstream in bytes
107*/
108M4OSA_Int32 M4_BitStreamParser_GetSize(void* pContext);
109
110void M4_MPEG4BitStreamParser_Init(void** pContext, void* pBitStream, M4OSA_Int32 size);
111
112/**
113* getMpegLengthFromInteger returns a decoded size value from an encoded one (SDL)
114*
115* @param pContext   : A pointer to the context internally used by the package
116* @param val : encoded value
117*
118* @returns size in a human readable form
119*/
120
121M4OSA_Int32 M4_MPEG4BitStreamParser_GetMpegLengthFromInteger(void* pContext, M4OSA_UInt32 val);
122
123
124/**
125 ************************************************************************
126 * @brief    Decode an MPEG4 Systems descriptor size from an encoded SDL size data.
127 * @note    The value is read from the current bitstream location.
128 * @param    pContext    (IN/OUT)  M4_BitStreamParser context.
129 * @return    Size in a human readable form
130 ************************************************************************
131*/
132M4OSA_Int32 M4_MPEG4BitStreamParser_GetMpegLengthFromStream(void* pContext);
133
134#endif /*__M4_BITSTREAMPARSER_H__*/
135
136