FLV学习（五）FlvParser源码阅读（3）解析FLV头部

解析FLV头部

入口函数

int CFlvParser::Parse(unsigned char *pBuf, int nBufSize, int &nUsedLen)
{
	int nOffset = 0;

	if (_pFlvHeader == 0)
	{
		CheckBuffer(9);
		// 解析FLV头部
		_pFlvHeader = CreateFlvHeader(pBuf+nOffset);
		nOffset += _pFlvHeader->nHeadSize;
	}

	while (1)
	{
		CheckBuffer(15);
		int nPrevSize = ShowU32(pBuf + nOffset);
		nOffset += 4;

		Tag *pTag = CreateTag(pBuf + nOffset, nBufSize-nOffset);
		if (pTag == NULL)
		{
			nOffset -= 4;
			break;
		}
		nOffset += (11 + pTag->_header.nDataSize);

		_vpTag.push_back(pTag);
	}

	nUsedLen = nOffset;
	return 0;
}

FLV头部解析函数

CFlvParser::FlvHeader *CFlvParser::CreateFlvHeader(unsigned char *pBuf)
{
	FlvHeader *pHeader = new FlvHeader;
	pHeader->nVersion = pBuf[3]; // 版本号
	pHeader->bHaveAudio = (pBuf[4] >> 2) & 0x01; // 是否有音频
	pHeader->bHaveVideo = (pBuf[4] >> 0) & 0x01; // 是否有视频
	pHeader->nHeadSize = ShowU32(pBuf + 5); // 头部长度

	pHeader->pFlvHeader = new unsigned char[pHeader->nHeadSize];
	memcpy(pHeader->pFlvHeader, pBuf, pHeader->nHeadSize);

	return pHeader;
}