修改的判断mp3文件方法

#include  < stdio.h >
#include < io.h >
#include < string .h >
#include < stdlib.h >
void  main()
... {
      FILE *fp;
      bool is_mp3 = false;
      unsigned char* cBuffer;
      int cBuffer_size=1024, i = 0;
      char LayerDescript, bRateIndex, bSampleRate;
      long int flength;
      char argv[]=...{"妃子笑"};
      /**//*######################Symbol Above###################################*/
      if((fp=fopen(argv,"rb")) ==NULL) ...{
            printf("open file err! "); exit(1);
      }
      /**//*###################### (mp3_FrameHeader) Reading #######################*/
      fseek(fp, 0L, SEEK_END); //移文件指针到文件尾
      flength = ftell(fp); //文件长

      rewind(fp);
      fseek(fp,10,1);
      while((ftell(fp)+4)<flength)
      ...{
            if (ftell(fp)+1024<=flength)
                  cBuffer_size=1024;
            else
                  cBuffer_size=flength-ftell(fp);

            cBuffer=(unsigned char *)malloc(cBuffer_size);
            if (cBuffer==NULL)// 检测动态内存分配是否已经成功
            ...{
                  if (fp!=NULL) fclose(fp);
                  printf("ERROR:Memory Exhausted!");
                  exit(1);
            }
            memset(cBuffer,0,cBuffer_size);
            fread(cBuffer,cBuffer_size,1,fp);
            for(i=0;i<(cBuffer_size-4); i++) ...{
                  LayerDescript = (cBuffer[i+1] & 0x6)>>1;
                  bRateIndex = cBuffer[i+2] /0x10;
                  bSampleRate = (cBuffer[i+2] & 0xA) >>2;

               if (cBuffer[i] ==0xFF 

                           && cBuffer[i+1] > 0xE0 

                           && bRateIndex != 0xF 

                           && LayerDescript != 0x0 

                           && bSampleRate < 0x3)  ...{
                        is_mp3 = true; 

                            cBuffer_size=-1; 

                            break;
                  }
            }
            free(cBuffer);
            if (cBuffer_size ==(-1) ) break;
      }
      fclose(fp);
      if (is_mp3) ...{
            printf("It's a mp3 file! ");
      }
      getchar();
}

源自：

http://hi.baidu.com/hmos/blog/item/e34a7bf0e4e5a4c27931aabe.html