FLV文件格式解析部分代码

转自：http://www.lougoo.com/blog/article.asp?id=856

前面在FLV文件格式大揭秘中介绍了FLV文件格式，其中也谈到了曾经编写的代码解析flv文件。应网友要求，现在把代码贴出来，仅供大家参考。因为这代码还是在2006年写的，现在看来有些地方还不够准确，解析的也不够完全，所以仅供参考。

flvheadpacket.h

#include "packet.h"

class CFlvHeadPacket : public CPacket
{
public:
    CFlvHeadPacket(void);
    CFlvHeadPacket(UInt8* pContent, UInt32 nLength);
    ~CFlvHeadPacket(void);

};

flvheadpacket.cpp

#include "stdafx.h"
#include "flvheadpacket.h"

CFlvHeadPacket::CFlvHeadPacket(void)
{
    m_nType = FLV_HEAD;
}

CFlvHeadPacket::CFlvHeadPacket(UInt8* pContent, UInt32 nLength)
{
    m_nType = FLV_HEAD;
    m_pContent = pContent;
    m_nLength = nLength;
}

CFlvHeadPacket::~CFlvHeadPacket(void)
{
}

flvmetapacket.h

#include "packet.h"
class CFlvMetaPacket : public CPacket
{
public:
    CFlvMetaPacket(void);
    CFlvMetaPacket(UInt8* pContent, UInt32 nLength);
    ~CFlvMetaPacket(void);
};

flvmetapacket.cpp

#include "stdafx.h"
#include "flvmetapacket.h"

CFlvMetaPacket::CFlvMetaPacket(void)
{
    m_nType = FLV_META;
}

CFlvMetaPacket::CFlvMetaPacket(UInt8* pContent, UInt32 nLength)
{
    m_nType = FLV_META;
    m_pContent = pContent;
    m_nLength = nLength;
}

CFlvMetaPacket::~CFlvMetaPacket(void)
{
}

flvdatapacket.h

#include "packet.h"

enum{
    FLV_UNKNOWN_FRAME,
    FLV_VIDEO_FRAME,
    FLV_AUDIO_FRAME
};

class CFlvDataPacket : public CPacket
{
public:
    CFlvDataPacket(void);
    CFlvDataPacket(UInt8* pContent, UInt32 nLength);
    ~CFlvDataPacket(void);

    void    Print();
    UInt8   m_nDataType;
    UInt32  m_nTime;
    UInt8   m_nFlag;
};

flvdatapacket.cpp

#include "stdafx.h"
#include "flvdatapacket.h"

CFlvDataPacket::CFlvDataPacket(void)
{
    m_nType = FLV_DATA;
    m_nDataType = FLV_UNKNOWN_FRAME;
}

CFlvDataPacket::CFlvDataPacket(UInt8* pContent, UInt32 nLength)
{
    m_nType = FLV_DATA;
    m_pContent = pContent;
    m_nLength = nLength;

    if ( m_pContent[0] == 8 )
        m_nDataType = FLV_AUDIO_FRAME;
    else if ( m_pContent[0] == 9 )
        m_nDataType = FLV_VIDEO_FRAME;
    else
        m_nDataType = FLV_UNKNOWN_FRAME;

    m_nTime = FOUR_CHARS_TO_INT(0,m_pContent[4],m_pContent[5],m_pContent[6]);

    m_nFlag = m_pContent[11];
}

CFlvDataPacket::~CFlvDataPacket(void)
{
}

void CFlvDataPacket::Print()
{
    printf("Type:%d,DataType=%d,Time=%d,Flag=%d,Length=%d/n",m_nType,m_nDataType,m_nTime,m_nFlag,m_nLength);
}

flvreader.h

#ifndef __FLVREADER_H__
#define __FLVREADER_H__

#define FLV_HEAD_LENGTH 13
#define FLV_DATA_HEAD_LENGTH 11

class CFlvDataPacket;
class CFlvHeadPacket;
class CFlvMetaPacket;

class CFlvReader
{
public:
    CFlvReader(void);
    ~CFlvReader(void);

public:
    SInt8*  m_sFile;
    FILE*   m_pFile;
    UInt32  m_nOffset;
    BOOL                SetFile(SInt8* sFile);
    FILESTAT64          GetFileStat64();
    FILESTAT            GetFileStat();
    CFlvHeadPacket*     ReadHeader();
    CFlvMetaPacket*     ReadMeta();
    CFlvDataPacket*     GetNextDataPacket();
};
#endif

flvreader.cpp

#include "stdafx.h"
#include "flvreader.h"
#include "flvdatapacket.h"
#include "flvheadpacket.h"
#include "flvmetapacket.h"


CFlvReader::CFlvReader(void)
{
    m_sFile = NULL;
    m_pFile = NULL;
    m_nOffset = 0;
}

CFlvReader::~CFlvReader(void)
{
    if ( m_pFile != NULL )
    {
        fclose( m_pFile );
        m_pFile = NULL;
    }
}

BOOL CFlvReader::SetFile(SInt8* sFile)
{
    if ( m_pFile != NULL )
    {
        fclose( m_pFile );
        m_pFile = NULL;
    }
    m_sFile     = sFile;
    m_pFile     = fopen( m_sFile, "rb" );
    return m_pFile != NULL;
}

CFlvHeadPacket* CFlvReader::ReadHeader()
{
    UInt8*  pContent    = new UInt8[FLV_HEAD_LENGTH];
    UInt32  nRead       = fread( pContent, sizeof(SInt8), FLV_HEAD_LENGTH, m_pFile );
    if ( nRead == FLV_HEAD_LENGTH )
    {
        return new CFlvHeadPacket(pContent, FLV_HEAD_LENGTH);
    }
    else
    {
        delete pContent;
        return NULL;
    }
}

CFlvMetaPacket* CFlvReader::ReadMeta()
{
    UInt8   buf[FLV_DATA_HEAD_LENGTH];
    UInt32  nRead   = fread( buf, sizeof(UInt8), FLV_DATA_HEAD_LENGTH, m_pFile );
    if ( nRead == FLV_DATA_HEAD_LENGTH )
    {
        if ( buf[0] == 18 )//meta
        {
            UInt32 nSize = FOUR_CHARS_TO_INT(0,buf[1],buf[2],buf[3]);
            UInt8*  pContent = new  UInt8[nSize+FLV_DATA_HEAD_LENGTH+4];
            memcpy(pContent,buf,FLV_DATA_HEAD_LENGTH);
            nRead = fread(&pContent[FLV_DATA_HEAD_LENGTH],sizeof(UInt8), nSize+4, m_pFile);
            if ( nRead = (nSize+4) )
            {
                return new CFlvMetaPacket(pContent,nSize+FLV_DATA_HEAD_LENGTH+4);
            }
            else
            {
                delete pContent;
                return NULL;
            }
        }
    }
    return NULL;
}

CFlvDataPacket* CFlvReader::GetNextDataPacket()
{
    UInt8   buf[FLV_DATA_HEAD_LENGTH];
    UInt32  nRead   = fread( buf, sizeof(UInt8), FLV_DATA_HEAD_LENGTH, m_pFile );
    if ( nRead == FLV_DATA_HEAD_LENGTH )
    {
        if ( buf[0] == 8 || buf[0] == 9 )
        {
            UInt32 nSize = FOUR_CHARS_TO_INT(0,buf[1],buf[2],buf[3]);
            UInt8*  pContent = new  UInt8[nSize+FLV_DATA_HEAD_LENGTH+4];
            memcpy(pContent,buf,FLV_DATA_HEAD_LENGTH);
            nRead = fread(&pContent[FLV_DATA_HEAD_LENGTH],sizeof(UInt8), nSize+4,m_pFile);
            if ( nRead = (nSize+4) )
            {
                return new CFlvDataPacket(pContent,nSize+FLV_DATA_HEAD_LENGTH+4);
            }
            else
            {
                delete pContent;
                return NULL;
            }
        }
    }
    return NULL;
}

FILESTAT CFlvReader::GetFileStat()
{
    FILESTAT    fileStat;
    memset(&fileStat,0,sizeof(FILESTAT));

    if ( m_pFile != NULL )
    {
        if ( _stat(m_sFile,&fileStat) != 0 )
        {
            printf( "/nGetFileStat Error!/n" );
        }
    }

    return fileStat;
}

FILESTAT64      CFlvReader::GetFileStat64()
{
    FILESTAT64  fileStat;
    memset(&fileStat,0,sizeof(FILESTAT64));

    if ( m_pFile != NULL )
    {
        if ( _stat64(m_sFile,&fileStat) != 0 )
        {
            printf( "/nGetFileStat64 Error!/n" );
        }
    }

    return fileStat;
}