ffmpeg 解析aac adts格式的文件

根据http://blog.csdn.net/sz76211822/article/details/53670069所讲，可以先读取文件的二进制数据到缓冲区，然后从缓冲区起始地址检测FFF。如果是，则解析协议。

代码如下：

#include "stdafx.h"
#include <windows.h>
#ifdef _WIN32
//Windows
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libavutil/opt.h"
#include "libavutil/parseutils.h"
#include "libavutil/avutil.h"
};
#else
//Linux...
#ifdef __cplusplus
extern "C"
{
#endif
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/opt.h>
#include <libavutil/parseutils.h>
#include <libavutil/avutil.h>
#ifdef __cplusplus
};
#endif
#endif

typedef struct _adts_header
{
unsigned int syncword:12;//同步字0xfff，说明一个ADTS帧的开始
unsigned char ID:1;//ID比较奇怪,标准文档中是这么说的”MPEG identifier, set to ‘1’. See ISO/IEC 11172-3″,但我写0了,也可以
unsigned char layer:2;//一般设置为0
unsigned char protection_absent:1;//是否误码校验
unsigned char profile:2;//表示使用哪个级别的AAC，如01 Low Complexity(LC)--- AACLC
unsigned char sampling_frequency_index:4;//表示使用的采样率下标0x3 48k ,0x4 44.1k, 0x5 32k
unsigned char private_bit:1;//一般设置为0
unsigned char channel_configuration:3;// 表示声道数
unsigned char original_copy:1;//一般设置为0
unsigned char home:1;//一般设置为0

unsigned char copyright_identification_bit:1;//一般设置为0
unsigned char copyright_identification_start:1;//一般设置为0
unsigned int frame_length:13;// 一个ADTS帧的长度包括ADTS头和raw data block
unsigned int adts_buffer_fullness:11;// 0x7FF 说明是码率可变的码流
unsigned char number_of_raw_data_blocks_in_frame:2;//表示ADTS帧中有number_of_raw_data_blocks_in_frame + 1个AAC原始帧.
};

void Process()
{
BYTE *btData = NULL;
DWORD dwRead = 0;
HANDLE hFile = CreateFile(L"E:\\video\\test.aac", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
if (hFile != INVALID_HANDLE_VALUE){
DWORD dwFilesize = GetFileSize(hFile, NULL);
btData = new BYTE[dwFilesize];
ReadFile(hFile, btData, dwFilesize, &dwRead, NULL);
CloseHandle(hFile);
}
if (dwRead < 9){
if (btData){
delete[] btData;
btData = NULL;
}
return;
}
int j = 0;
int i = 0;
int nAdtsHeader_Size = 9;//根据AAC adts协议头可知，协议大小为9个字节
while(i < dwRead - nAdtsHeader_Size){
if(btData[i] == 0xff && (btData[i + 1]>>4) == 0xf){//判断是aac的adts封装格式
DWORD dwErr = 0;
printf("%d  %d  %02x  %x  %x  %x", j, i,
(btData[i]<<4) | (btData[i + 1]>>4),
(btData[i + 1]>>3) & 0x1,
(btData[i + 1]>>1) & 0x3,
btData[i + 1] & 0x1);

switch((btData[i + 2]>>6) & 0x3){
case 0:
printf("  Main");
break;
case 1:
printf("  LC");
break;
case 2:
printf("  SSR");
break;
default:
printf("  unknown");
break;
}

switch((btData[i + 2]>>2) & 0xF){
case 0:
printf("  96000Hz");
break;
case 1:
printf("  88200Hz");
break;
case 2:
printf("  64000Hz");
break;
case 3:
printf("  48000Hz");
break;
case 4:
printf("  44100Hz");
break;
case 5:
printf("  32000Hz");
break;
case 6:
printf("  24000Hz");
break;
case 7:
printf("  22050Hz");
break;
case 8:
printf("  16000Hz");
break;
case 9:
printf("  12000Hz");
break;
case 10:
printf("  11025Hz");
break;
case 11:
printf("  8000Hz");
break;
default:
printf(" unknown");
break;
}

printf("%x  %x  %x  %x  %x  %x  %d  %02x  %x\n",
(btData[i + 2]>>1) & 0x1,
((btData[i + 2] & 0x1)<<2) | ((btData[i + 3]>>6) & 0x3),
(btData[i + 3]>>5) & 0x1,
(btData[i + 3]>>4) & 0x1,

(btData[i + 3]>>3) & 0x1,
(btData[i + 3]>>2) & 0x1,
(((btData[i + 3]) & 0x3)<<11) | (btData[i + 4])<<3 | ((btData[i + 5]>>5) & 0x7),
((btData[i + 5] & 0x1F)<<6)|((btData[i + 6]>>2) & 0x3F),
btData[i + 6] & 0x3);
j++;
i += (((btData[i + 3]) & 0x3)<<11) | (btData[i + 4])<<3 | ((btData[i + 5]>>5) & 0x7);//偏移一个音频帧的大小
}
else{
i++;
}
}

if (btData){
delete[] btData;
btData = NULL;
}
return;
}

int _tmain(int argc, _TCHAR* argv[])
{
Process();
return 0;
}

http://download.csdn.net/detail/sz76211822/9713309