AAC音频格式分析与解码

NeAACDecHandleNEAACAPINeAACDecOpen(void);

创建解码环境并返回一个句柄

voidNEAACAPINeAACDecClose(NeAACDecHandlehDecoder);

关闭解码环境

NeAACDecConfigurationPtrNEAACAPINeAACDecGetCurrentConfiguration(NeAACDecHandlehDecoder);

获取当前解码器库的配置

unsignedcharNEAACAPINeAACDecSetConfiguration(NeAACDecHandlehDecoder,NeAACDecConfigurationPtrconfig);

为解码器库设置一个配置结构

longNEAACAPINeAACDecInit(NeAACDecHandlehDecoder,unsignedchar*buffer,unsignedlongbuffer_size,unsignedlong*samplerate,unsignedchar*channels);

初始化解码器库

void*NEAACAPINeAACDecDecode(NeAACDecHandlehDecoder,NeAACDecFrameInfo*hInfo,unsignedchar*buffer,unsignedlongbuffer_size);

解码AAC数据

/**

*

*filename:MyAACDecoder.h

*summary:convertaactowave

*author:caosiyang

*email:csy3228@gmail.com

*

*/

#ifndef__MYAACDECODER_H__

#define__MYAACDECODER_H__

#include"Buffer.h"

#include"mytools.h"

#include"WaveFormat.h"

#include"faad.h"

#include<iostream>

usingnamespacestd;

classMyAACDecoder{

public:

MyAACDecoder();

~MyAACDecoder();

int32_tDecode(char*aacbuf,uint32_taacbuflen);

constchar*WavBodyData()const{

return_mybuffer.Data();

}

uint32_tWavBodyLength()const{

return_mybuffer.Length();

}

constchar*WavHeaderData()const{

return_wave_format.getHeaderData();

}

uint32_tWavHeaderLength()const{

return_wave_format.getHeaderLength();

}

private:

MyAACDecoder(constMyAACDecoder&dec);

MyAACDecoder&operator=(constMyAACDecoder&rhs);

//initAACdecoder

int32_t_init_aac_decoder(char*aacbuf,int32_taacbuflen);

//destroyaacdecoder

void_destroy_aac_decoder();

//parseAACADTSheader,getframelength

uint32_t_get_frame_length(constchar*aac_header)const;

//AACdecoderproperties

NeAACDecHandle_handle;

unsignedlong_samplerate;

unsignedchar_channel;

Buffer_mybuffer;

WaveFormat_wave_format;

};

#endif/*__MYAACDECODER_H__*/

#include"MyAACDecoder.h"

MyAACDecoder::MyAACDecoder():_handle(NULL),_samplerate(44100),_channel(2),_mybuffer(4096,4096){

}

MyAACDecoder::~MyAACDecoder(){

_destroy_aac_decoder();

}

int32_tMyAACDecoder::Decode(char*aacbuf,uint32_taacbuflen){

int32_tres=0;

if(!_handle){

if(_init_aac_decoder(aacbuf,aacbuflen)!=0){

ERR1("::::initaacdecoderfailed::::");

return-1;

}

}

//clean_mybuffer

_mybuffer.Clean();

uint32_tdonelen=0;

uint32_twav_data_len=0;

while(donelen<aacbuflen){

uint32_tframelen=_get_frame_length(aacbuf+donelen);

if(donelen+framelen>aacbuflen){

break;

}

//decode

NeAACDecFrameInfoinfo;

void*buf=NeAACDecDecode(_handle,&info,(unsignedchar*)aacbuf+donelen,framelen);

if(buf&&info.error==0){

if(info.samplerate==44100){

//44100Hz

//src:2048samples,4096bytes

//dst:2048samples,4096bytes

uint32_ttmplen=info.samples*16/8;

_mybuffer.Fill((constchar*)buf,tmplen);

wav_data_len+=tmplen;

}elseif(info.samplerate==22050){

//22050Hz

//src:1024samples,2048bytes

//dst:2048samples,4096bytes

short*ori=(short*)buf;

shorttmpbuf[info.samples*2];

uint32_ttmplen=info.samples*16/8*2;

for(int32_ti=0,j=0;i<info.samples;i+=2){

tmpbuf[j++]=ori[i];

tmpbuf[j++]=ori[i+1];

tmpbuf[j++]=ori[i];

tmpbuf[j++]=ori[i+1];

}

_mybuffer.Fill((constchar*)tmpbuf,tmplen);

wav_data_len+=tmplen;

}

}else{

ERR1("NeAACDecDecode()failed");

}

donelen+=framelen;

}

//generateWaveheader

_wave_format.setSampleRate(_samplerate);

_wave_format.setChannel(_channel);

_wave_format.setSampleBit(16);

_wave_format.setBandWidth(_samplerate*16*_channel/8);

_wave_format.setDataLength(wav_data_len);

_wave_format.setTotalLength(wav_data_len+44);

_wave_format.GenerateHeader();

return0;

}

uint32_tMyAACDecoder::_get_frame_length(constchar*aac_header)const{

uint32_tlen=*(uint32_t*)(aac_header+3);

len=ntohl(len);//LittleEndian

len=len<<6;

len=len>>19;

returnlen;

}

int32_tMyAACDecoder::_init_aac_decoder(char*aacbuf,int32_taacbuflen){

unsignedlongcap=NeAACDecGetCapabilities();

_handle=NeAACDecOpen();

if(!_handle){

ERR1("NeAACDecOpen()failed");

_destroy_aac_decoder();

return-1;

}

NeAACDecConfigurationPtrconf=NeAACDecGetCurrentConfiguration(_handle);

if(!conf){

ERR1("NeAACDecGetCurrentConfiguration()failed");

_destroy_aac_decoder();

return-1;

}

NeAACDecSetConfiguration(_handle,conf);

longres=NeAACDecInit(_handle,(unsignedchar*)aacbuf,aacbuflen,&_samplerate,&_channel);

if(res<0){

ERR1("NeAACDecInit()failed");

_destroy_aac_decoder();

return-1;

}

//fprintf(stdout,"SampleRate=%d\n",_samplerate);

//fprintf(stdout,"Channel=%d\n",_channel);

//fprintf(stdout,"::::initaacdecoderdone::::\n");

return0;

}

voidMyAACDecoder::_destroy_aac_decoder(){

if(_handle){

NeAACDecClose(_handle);

_handle=NULL;

}

}