linux环境C语言实现：h264与pcm封装成mp4视频格式
前言
H.264是压缩过的数据，PCM是原始数据，MP4是一种视频封装格式。实际H.264与PCM不能直接合成MP4格式，因为音频格式不对。这里需要中间对音频做一次压缩处理。基本流程为：将PCM音频数据压缩成AAC格式音频数据，再将AAC与H.264合成MP4视频格式。
（一）PCM压缩为AAC格式
直接上代码，接口函数的实现如下：
#include <stdio.h>
#include "faac.h"
#include "pcm2acc.h"
int Hst_PCM_To_AAC(PCM_TO_MP4_PARA_S stPara)
{
// 定义别名
typedef unsigned char BYTE;
unsigned long nSampleRate = 8000;
unsigned int nChannels = 1;
unsigned int nPCMBitSize = 16;
unsigned long nInputSamples = 0;
unsigned long nMaxOutputBytes = 0;
faacEncHandle hEncoder = {0};
//nSampleRate = stPara.u64SampleRate;
//nChannels = stPara.u32Channels;
//nPCMBitSize = stPara.u32PCMBitSize;
FILE* fpIn = fopen(stPara.arrs8PCMFilename, "rb");
FILE* fpOut = fopen(stPara.arrs8AACFilename, "wb");
//FILE* fpIn = fopen("./ExportChannel0Audio.cpm", "rb");
//FILE* fpOut = fopen("./test.aac", "wb");
if(fpIn==NULL || fpOut==NULL)
{
printf("File Open error \n");
return -1;
}
// 打开faac编码器引擎
hEncoder = faacEncOpen(nSampleRate, nChannels, &nInputSamples, &nMaxOutputBytes);
if(hEncoder == NULL)
{
printf("open faac encoder error !\n");
return -1;
}
// 分配内存信息
int nPCMBufferSize = nInputSamples*nPCMBitSize/8;
BYTE* pbPCMBuffer = new BYTE[nPCMBufferSize];
BYTE* pbAACBuffer = new BYTE[nMaxOutputBytes];
// 获取当前编码器信息
faacEncConfigurationPtr pConfiguration = {0};
pConfiguration = faacEncGetCurrentConfiguration(hEncoder);
// 设置编码配置信息
/*
PCM Sample Input Format
0 FAAC_INPUT_NULL invalid, signifies a misconfigured config
1 FAAC_INPUT_16BIT native endian 16bit
2 FAAC_INPUT_24BIT native endian 24bit in 24 bits (not implemented)
3 FAAC_INPUT_32BIT native endian 24bit in 32 bits (DEFAULT)
4 FAAC_INPUT_FLOAT 32bit floating point
*/
pConfiguration->inputFormat = FAAC_INPUT_16BIT;
// 0 = Raw; 1 = ADTS
pConfiguration->outputFormat = 1;
// AAC object types
//#define MAIN 1
//#define LOW 2
//#define SSR 3
//#define LTP 4
pConfiguration->aacObjectType = LOW;
pConfiguration->allowMidside = 0;
pConfiguration->useLfe = 0;
pConfiguration->bitRate = 48000;
pConfiguration->bandWidth = 32000;
// 其他的参数不知道怎么配置，毕竟对音频不熟
// 不过当前的设置可以实现转换，不过声音好像有一丢丢怪异
// 这一块的配置信息很重要，错了会导致转码失败，然后你以为代码其他地方错了
// 重置编码器的配置信息
faacEncSetConfiguration(hEncoder, pConfiguration);
size_t nRet = 0;
printf("start data convert : \n");
int i = 0;
while( (nRet = fread(pbPCMBuffer, 1, nPCMBufferSize, fpIn)) > 0)
{
printf("\b\b\b\b\b\b\b\b%-8d", ++i);
nInputSamples = nRet / (nPCMBitSize/8);
// 编码
nRet = faacEncEncode(hEncoder, (int*) pbPCMBuffer, nInputSamples, pbAACBuffer, nMaxOutputBytes);
// 写入转码后的数据
fwrite(pbAACBuffer, 1, nRet, fpOut);
}
// 扫尾工作
faacEncClose(hEncoder);
fclose(fpOut);
fclose(fpIn);
delete[] pbAACBuffer;
delete[] pbPCMBuffer;
return 0;
}
int main(void)
{
PCM_TO_MP4_PARA_S l_stPara;
Hst_PCM_To_AAC(l_stPara);
}
整个工程如下：
.
├── faac-1.29.9.2_ARM.tar.gz
├── faaccfg.h
├── faac.h
├── lib
│ ├── libfaac.a
│ ├── libfaac.la
│ ├── libfaac.so
│ ├── libfaac.so.0
│ └── libwisdom_aac.so
├── pcm2acc.cpp
├── pcm2acc.h
└── test.c
注意：我这些库是使用了海思的交叉编译，并不能直接在PC机上运行。如果需要在PC机上运行，需要自己重新编译库文件，这里只提供一种方法。完整工程下载路径：PCM音频转AAC格式
（二）H264与PCM合成MP4
这套代码是在网上下载的，初步使用并没发现其他的什么异常。他原来是用来做AVI转MP4和MP4转AVI的，中间的音频转换他们没有提供，于是我在这基础上做了一些修改，直接将h264与AAC合成MP4格式。主要代码如下：
int H264AacToMp4(H264_AAC_PARA stPara,char* mp4FilePath)
{
int VIDEO_BUF_LEN = 327680;
int AUDIO_BUF_LEN = 100000;
CAviFmtInterface aviFormatInsatance;
CMp4FmtInterface mp4FormatInsatance;
int framew = stPara.u32VideoFrameW;
int frameh = stPara.u32VideoFrameH;
long framerate = stPara.u32VideoFrameRate;
char * vidbuf = (char*)malloc(VIDEO_BUF_LEN);
char * audbuf = (char*)malloc(AUDIO_BUF_LEN);
if(vidbuf==NULL || audbuf==NULL)
{
return -1;
}
mp4FormatInsatance.OpenFile(mp4FilePath,OPEN_MODEL_W);
mp4FormatInsatance.SetMp4Param((u_int16_t)framew,(u_int16_t)frameh,framerate);
FILE *in_aac = NULL;
FILE *in_h264 = NULL;
in_aac = fopen(stPara.arrs8AACFileName,"rb");
if(in_aac == NULL)
{
printf("Can't open the aac file\n");
return -1;
}
in_h264 = fopen(stPara.arrs8H264FileName,"rb") ;
if(in_h264== NULL)
{
printf("Can't open the h264 file\n");
return -1;
}
//音频
fseek(in_aac,0,SEEK_END);
file_aac_length = ftell(in_aac);
fseek(in_aac,0,SEEK_SET);
if(file_aac_length == 0)
{
return -1;
}
//音频
AACBUFFER aacbuffer;
init_aac_buf(&aacbuffer);
fread(aacbuffer.buf,1,AACBUFSIZE,in_aac);
ADTS_HEADER adts_header;
int idx = 0;
int idxAudio = 0;
while (1)//read and write avi per fream
{
init_adts_header(&adts_header);
long readLen = 0;
readLen = aviFormatInsatance.GetAnnexbNALU(in_h264, vidbuf);
if(readLen<=0)
{
break;
};
if(!mp4FormatInsatance.WriteVideoFrameData((unsigned char*)vidbuf,readLen))
{
printf("Write video frame data fail. The frame index is:%05d.\n",idx);
}
idx++;
}
idx = 0;
while(1)
{
if(read_aac_frame(&aacbuffer,&adts_header))
{
if(!mp4FormatInsatance.WriteAudioFrameData((const unsigned char*)(adts_header.aac_frame_start-7),adts_header.aac_frame_length+7))//此接口需要的数据信息，需要包含7个字节的头信息
{
printf("error!\n");
break;
}
idx++;
}
else
{
printf("Reach to the end of aac file!\n");
break;
}
}
mp4FormatInsatance.Close();
if(NULL!=in_h264)
{
fclose(in_h264);
in_h264 = NULL;
}
if(NULL!=in_aac)
{
fclose(in_aac);
in_h264 = NULL;
}
free(vidbuf);
free(audbuf);
return 0;
}
代码结构如下：
.
├── avilib
├── AviToMp4.h
├── include
├── libwisdom_hi3520_avi2mp4.so
├── Makefile
├── mediaconvert
├── mp4file
├── mp4lib
├── Mp4ToAvi.h
├── obj
├── test.cpp
└── type.h
在 liwen01 公众号中回复 音视频 获取工程代码，本章代码工程名为：MP4格式合成.zip
