H264视频编码成MP4文件
最近需要将H264视频编码成MP4格式。研究了一下，一种方法是采用ffmpeg库，可以先将H264文件解码，再编码生成MP4文件，但这种方式效率较低，10M的视频可能需要几秒钟才能完成。另一种方式根据MP4文件协议直接将H264包封装成MP4格式，由于是直接基于MP4的封装，因而效率很高。H264可以很方便的封装成FLV文件，但MP4格式格式相对比较复杂，封装起来会比较麻烦。由于没时间研究MP4协议，在Google Code上找到一个开源的MP4编解码库Mp4v2（https://code.google.com/p/mp4v2/），通过Mp4v2可以很方便的将H264编码成MP4格式文件。为了方便使用，基于该库封装了一个MP4Encoder类，MP4Encoder封装的接口如下。目前仅支持将H264文件或数据帧编码成MP4文件。
class MP4Encoder
{
public:
MP4Encoder(void);
~MP4Encoder(void);
public:
// open or creat a mp4 file.
MP4FileHandle CreateMP4File(const char *fileName,int width,int height,int timeScale = 90000,int frameRate = 25);
// wirte 264 metadata in mp4 file.
bool Write264Metadata(MP4FileHandle hMp4File,LPMP4ENC_Metadata lpMetadata);
// wirte 264 data, data can contain multiple frame.
int WriteH264Data(MP4FileHandle hMp4File,const unsigned char* pData,int size);
// close mp4 file.
void CloseMP4File(MP4FileHandle hMp4File);
// convert H264 file to mp4 file.
// no need to call CreateMP4File and CloseMP4File,it will create/close mp4 file automaticly.
bool WriteH264File(const char* pFile264,const char* pFileMp4);
// Prase H264 metamata from H264 data frame
static bool PraseMetadata(const unsigned char* pData,int size,MP4ENC_Metadata &metadata);
};
客户端调用示例代码：
#include
#include "MP4Encoder\MP4Encoder.h"
int main(int argc, char** argv)
{
MP4Encoder mp4Encoder;
// convert H264 file to mp4 file
mp4Encoder.WriteH264File("test.264","test.mp4");
} /********************************************************************
filename: MP4Encoder.h
created: 2013-04-16
author: firehood
purpose: MP4编码器，基于开源库mp4v2实现（https://code.google.com/p/mp4v2/）。
*********************************************************************/
#pragma once
#include "mp4v2\mp4v2.h"
// NALU单元
typedef struct _MP4ENC_NaluUnit
{
int type;
int size;
unsigned char *data;
}MP4ENC_NaluUnit;
typedef struct _MP4ENC_Metadata
{
// video, must be h264 type
unsigned int nSpsLen;
unsigned char Sps[1024];
unsigned int nPpsLen;
unsigned char Pps[1024];
} MP4ENC_Metadata,*LPMP4ENC_Metadata;
class MP4Encoder
{
public:
MP4Encoder(void);
~MP4Encoder(void);
public:
// open or creat a mp4 file.
MP4FileHandle CreateMP4File(const char *fileName,int width,int height,int timeScale = 90000,int frameRate = 25);
// wirte 264 metadata in mp4 file.
bool Write264Metadata(MP4FileHandle hMp4File,LPMP4ENC_Metadata lpMetadata);
// wirte 264 data, data can contain multiple frame.
int WriteH264Data(MP4FileHandle hMp4File,const unsigned char* pData,int size);
// close mp4 file.
void CloseMP4File(MP4FileHandle hMp4File);
// convert H264 file to mp4 file.
// no need to call CreateMP4File and CloseMP4File,it will create/close mp4 file automaticly.
bool WriteH264File(const char* pFile264,const char* pFileMp4);
// Prase H264 metamata from H264 data frame
static bool PraseMetadata(const unsigned char* pData,int size,MP4ENC_Metadata &metadata);
private:
// read one nalu from H264 data buffer
static int ReadOneNaluFromBuf(const unsigned char *buffer,unsigned int nBufferSize,unsigned int offSet,MP4ENC_NaluUnit &nalu);
private:
int m_nWidth;
int m_nHeight;
int m_nFrameRate;
int m_nTimeScale;
MP4TrackId m_videoId;
};
MP4Encoder.cpp
/********************************************************************
filename: MP4Encoder.cpp
created: 2013-04-16
author: firehood
purpose: MP4编码器，基于开源库mp4v2实现（https://code.google.com/p/mp4v2/）。
*********************************************************************/
#include "MP4Encoder.h"
#include
#define BUFFER_SIZE (1024*1024)
MP4Encoder::MP4Encoder(void):
m_videoId(NULL),
m_nWidth(0),
m_nHeight(0),
m_nTimeScale(0),
m_nFrameRate(0)
{
}
MP4Encoder::~MP4Encoder(void)
{
}
MP4FileHandle MP4Encoder::CreateMP4File(const char *pFileName,int width,int height,int timeScale/* = 90000*/,int frameRate/* = 25*/)
{
if(pFileName == NULL)
{
return false;
}
// create mp4 file
MP4FileHandle hMp4file = MP4Create(pFileName);
if (hMp4file == MP4_INVALID_FILE_HANDLE)
{
printf("ERROR:Open file fialed.\n");
return false;
}
m_nWidth = width;
m_nHeight = height;
m_nTimeScale = 90000;
m_nFrameRate = 25;
MP4SetTimeScale(hMp4file, m_nTimeScale);
return hMp4file;
}
bool MP4Encoder::Write264Metadata(MP4FileHandle hMp4File,LPMP4ENC_Metadata lpMetadata)
{
m_videoId = MP4AddH264VideoTrack
(hMp4File,
m_nTimeScale,
m_nTimeScale / m_nFrameRate,
m_nWidth, // width
m_nHeight,// height
lpMetadata->Sps[1], // sps[1] AVCProfileIndication
lpMetadata->Sps[2], // sps[2] profile_compat
lpMetadata->Sps[3], // sps[3] AVCLevelIndication
3); // 4 bytes length before each NAL unit
if (m_videoId == MP4_INVALID_TRACK_ID)
{
printf("add video track failed.\n");
return false;
}
MP4SetVideoProfileLevel(hMp4File, 0x01); // Simple Profile @ Level 3
// write sps
MP4AddH264SequenceParameterSet(hMp4File,m_videoId,lpMetadata->Sps,lpMetadata->nSpsLen);
// write pps
MP4AddH264PictureParameterSet(hMp4File,m_videoId,lpMetadata->Pps,lpMetadata->nPpsLen);
return true;
}
int MP4Encoder::WriteH264Data(MP4FileHandle hMp4File,const unsigned char* pData,int size)
{
if(hMp4File == NULL)
{
return -1;
}
if(pData == NULL)
{
return -1;
}
MP4ENC_NaluUnit nalu;
int pos = 0, len = 0;
while (len = ReadOneNaluFromBuf(pData,size,pos,nalu))
{
if(nalu.type == 0x07) // sps
{
// 添加h264 track
m_videoId = MP4AddH264VideoTrack
(hMp4File,
m_nTimeScale,
m_nTimeScale / m_nFrameRate,
m_nWidth, // width
m_nHeight, // height
nalu.data[1], // sps[1] AVCProfileIndication
nalu.data[2], // sps[2] profile_compat
nalu.data[3], // sps[3] AVCLevelIndication
3); // 4 bytes length before each NAL unit
if (m_videoId == MP4_INVALID_TRACK_ID)
{
printf("add video track failed.\n");
return 0;
}
MP4SetVideoProfileLevel(hMp4File, 1); // Simple Profile @ Level 3
MP4AddH264SequenceParameterSet(hMp4File,m_videoId,nalu.data,nalu.size);
}
else if(nalu.type == 0x08) // pps
{
MP4AddH264PictureParameterSet(hMp4File,m_videoId,nalu.data,nalu.size);
}
else
{
int datalen = nalu.size+4;
unsigned char *data = new unsigned char[datalen];
// MP4 Nalu前四个字节表示Nalu长度
data[0] = nalu.size>>24;
data[1] = nalu.size>>16;
data[2] = nalu.size>>8;
data[3] = nalu.size&0xff;
memcpy(data+4,nalu.data,nalu.size);
if(!MP4WriteSample(hMp4File, m_videoId, data, datalen,MP4_INVALID_DURATION, 0, 1))
{
return 0;
}
delete[] data;
}
pos += len;
}
return pos;
}
int MP4Encoder::ReadOneNaluFromBuf(const unsigned char *buffer,unsigned int nBufferSize,unsigned int offSet,MP4ENC_NaluUnit &nalu)
{
int i = offSet;
while(i=0; i--)
{
if(buffer[i--] == 0x01 &&
buffer[i--] == 0x00 &&
buffer[i--] == 0x00 &&
buffer[i--] == 0x00
)
{
writelen = i+5;
break;
}
}
writelen = WriteH264Data(hMp4File,buffer,writelen);
if(writelen<=0)
{
break;
}
memcpy(buffer,buffer+writelen,readlen-writelen+1);
pos = readlen-writelen+1;
}
fclose(fp);
delete[] buffer;
CloseMP4File(hMp4File);
return true;
}
bool MP4Encoder:: PraseMetadata(const unsigned char* pData,int size,MP4ENC_Metadata &metadata)
{
if(pData == NULL || size<4)
{
return false;
}
MP4ENC_NaluUnit nalu;
int pos = 0;
bool bRet1 = false,bRet2 = false;
while (int len = ReadOneNaluFromBuf(pData,size,pos,nalu))
{
if(nalu.type == 0x07)
{
memcpy(metadata.Sps,nalu.data,nalu.size);
metadata.nSpsLen = nalu.size;
bRet1 = true;
}
else if((nalu.type == 0x08))
{
memcpy(metadata.Pps,nalu.data,nalu.size);
metadata.nPpsLen = nalu.size;
bRet2 = true;
}
pos += len;
}
if(bRet1 && bRet2)
{
return true;
}
return false;
}