提取FLV视频文件中的音频到MP3文件（代码）

// 提取FLV视频文件中的音频到MP3文件

// FLV2MP3.cpp, visual c++ 6.0

// Usage: FLV2mp3 filename.flv

// 江岳华 2010,5 本程序只说明原理，未注意代码风格

 

#include <stdio.h>

#include <stdlib.h>

#include <winsock2.h>

#include <windows.h>

#include <io.h>

#include <conio.h>

#include <string.h>

#pragma comment(lib,"ws2_32")

typedef struct tagTAG

{

 UINT prelen;

 BYTEtype;//video=0x09,audio=0x08,metadata=0x12

 BYTE size24[3];

 BYTE ts24[3];

 BYTE tshigh;

 BYTE sid[3];//0x000000

}

TAG;

typedef struct tagTAG2

{

 UINT prelen;

 BYTEtype;//video=0x09,audio=0x08,metadata=0x12

 UINT size;

 UINT ts;

 UINT sid;

}

TAG2;

void tag_to_tag2(TAG* a, TAG2* b)

{

 if(!a || !b)return;

 memset(b,0,sizeof(TAG2));

 b->prelen =htonl(a->prelen);

 b->type =a->type;

 BYTE* p =(BYTE*)(a->size24);

 b->size =(p[0]<<16)|(p[1]<<8)|p[2];

 p = (BYTE*)(a->ts24);

 b->ts =(a->tshigh<<24)|(p[0]<<16)|(p[1]<<8)|p[2];

 p = (BYTE*)(a->sid);

 b->sid =(p[0]<<16)|(p[1]<<8)|p[2];

}

int main(int argc, char* argv[])

{

 if(argc<2)

 {

  puts("Usage: FLV2mp3filename.flv");

  return 0;

 }

 if(strlen(argv[1])>=256)

 {

  printf("File name lengtherror!\n");

  return 0;

 }

 FILE* fp = fopen(argv[1],"rb");

 if(!fp)

 {

  printf("Open file %sfailed!\n",argv[1]);

  return 0;

 }

 long flen = filelength(fileno(fp));

 if(flen<24)

 {

  printf("File lengtherror!\n");

  fclose(fp);

  return 0;

 }

 fseek(fp,0,0);

 unsigned char* buf = new unsignedchar[flen];

 if(!buf)

 {

  printf("Memory overerror!\n");

  fclose(fp);

  return 0;

 }

 long pos=0;

 while (pos < flen)

 {

  printf("\r%d",pos);

  int ret =fread(buf+pos,1,flen-pos,fp);

  if(ret <1)break;

  pos += ret;

  printf("\r%d",pos);

  if(pos >=flen)break;

 }

 if(pos != flen)

 {

  printf("Read file lengtherror!\n");

  delete[] buf;

  fclose(fp);

  return 0;

 }

 puts("\nRead file OK!\n");

 unsigned char* h = (unsigned char*)buf;

 if(memcmp(h,"FLV",3)!=0)

 {

  printf("Not flvfile!\n");

  delete[] buf;

  fclose(fp);

  return 0;

 }

 if(h[3]!=1)

 {

  printf("Not flv ver1.0!\n");

  delete[] buf;

  fclose(fp);

  return 0;

 }

 if(h[4] > 0x07)

 {

  printf("Flv header avbyteerror!\n");

  delete[] buf;

  fclose(fp);

  return 0;

 }

 if(h[4] & 0x02)

 {

  printf("Flv header avbyte error2!\n");

  delete[] buf;

  fclose(fp);

  return 0;

 }

 if(h[4] & 0x04)

  puts("has audio.");

 

 if(h[4] & 0x01)

  puts("has video.");

 UINT offset =(h[5]<<24)|(h[6]<<16)|(h[7]<<8)|h[8];

 printf("body offset = %d\n",offset);

 if(offset!=9)

  puts("warring: body offset !=9!!!\n");

 h += offset;

#define WRITE_AUDIO

#ifdef WRITE_AUDIO

 FILE *fw = NULL;

 char name[512];

 memset(name,0,sizeof(name));

 strncpy(name,argv[1],strlen(argv[1]));

 name[sizeof(name)-5]='\0';

 strcat(name,".mp3");

 fw = fopen(name,"wb");

#endif

 while ((h+15)<(buf+pos))

 {

  TAG* t = (TAG*)h;

  TAG2 t2;

  memset(&t2,0,sizeof(TAG2));

  tag_to_tag2(t,&t2);

  printf("prelen=%08lx,type=%x,size=%08lx,ts=%08lx\n",t2.prelen,t2.type,t2.size,t2.ts);

  BYTE *d = h+15;

  if(t2.type ==0x08)//audio

  {

   int len =t2.size-1;

   intsoundfmt=(d[0]>>4)&0x0f;

    //0= Linear PCM, platform endian

    //1= ADPCM  Formats 7, 8, 14, and 15are

    //2= MP3  reserved for internaluse

    //3= Linear PCM, little endian

    //4= Nellymoser 16-kHz mono AAC is supported in Flash

    //5= Nellymoser 8-kHz mono Player9,0,115,0 and higher.

    //6= Nellymoser

    //7= G.711 A-law logarithmic PCM Speex is supported in Flash

    //8= G.711 mu-law logarithmic PCM Player10 and higher.

    //9= reserved

    //10= AAC

    //11= Speex

    //14= MP3 8-Khz

    //15= Device-specific sound

   intsoundrate=(d[0]>>2)&0x03;

    //0= 5.5-kHz For AAC: always 3

    //1= 11-kHz

    //2= 22-kHz

    //3= 44-kHz

   intsoundsize=(d[0]>>1)&0x01;

    //0= snd8Bit parameter only pertains to

    //1= snd16Bit uncompressed formats.

    //  Compressedformats always

    //  decodeto 16 bits internally.

    //  0= snd8Bit

    //  1= snd16Bit

   intsoundtype=d[0]&0x01;

    //0= sndMono For Nellymoser: always 0

    //1= sndStereo For AAC: always 1

   printf("soundfmt=%d,soundrate=%d,soundsize=%d,soundtype=%d\n",

    soundfmt,soundrate,soundsize,soundtype);

#ifdef WRITE_AUDIO

   if(soundfmt==2)//MP3

    if(fw)fwrite(d+1,1,len,fw);

#endif

  }

  else if(t2.type ==0x09)//video

  {

  }

  else if(t2.type ==0x12)//metadata

  {

  }

  //准备下次

  h += (15+t2.size);

 }

#ifdef WRITE_AUDIO

 if(fw)fclose(fw);

 fw = NULL;

#endif

 delete[] buf;

 fclose(fp);

 return 0;

}