wav格式音频转换成flv格式音频(四)

最新推荐文章于 2020-04-21 14:22:49 发布

山水间

最新推荐文章于 2020-04-21 14:22:49 发布

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分类专栏：山水间文集文章标签： flv header

本文链接：https://blog.youkuaiyun.com/linyanwen99/article/details/7542679

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本文介绍如何将AMR格式音频转换为FLV，重点在于转换流程及关键的while循环，其中涉及AMR数据编码为WAV，再封装成FLV格式的过程。转换过程中使用了D_IF_decode函数进行编码，并详细描述了各步骤。

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前三篇已经对wav音频格式转换成flv格式做了一些较为详细的说明，这一篇把最后一部分写完，转换的流程为，先把amr的转化成wav格式，再把wav格式封装成

flv格式，本篇关键部分是while循环里面的部分，其他部分可以略过，其中函数D_IF_decode(st, serial, synth16, _good_frame);的作用是把一帧amr数据编码成对应的一帧wav格式数据，调用该函数需要一些相关amr音频的编解码库，需要的朋友可以上网找找

int amrToWav(const char* amrData,int amrDataLen,char* wavData){
/*
* 将长为amrDataLen个字节的AMR音频数据amrData，转换为WAV，写入wavData
* 成功返回WAV数据的字节数，失败返回-1
*/
UWord8 serial[NB_SERIAL_MAX];
Word8 synth8[L_FRAME16k*2];
Word16 synth16[L_FRAME16k];
Word16 mode = 0;
Word16 readLen = 0;
Word16 writeLen = L_FRAME16k * 2;
Word32 readByteSum = 0;
Word32 writeByteSum = 0;
Word16 i,j;
char* tempPt = synth8;
//////////////////////
unsigned char flvPreviousTagSizeTemp[10];
unsigned char* flvPreviousTagNum = flvPreviousTagSizeTemp;
unsigned char flvTagDataFirstByteTemp[10];
unsigned char* flvTagDataFirstByte = flvTagDataFirstByteTemp;
unsigned char flvHeaderTemp[50];
unsigned char* flvHeader = flvHeaderTemp;
unsigned char flvTagHeaderTemp[50];
unsigned char* flvTagHeader = flvTagHeaderTemp;
Word32 flvHeaderSize = 0;
Word32 flvTagHeaderSize = 0;
Word32 flvTagDataFirstByteSize = 0;
Word32 flvprevioustagsize = 0;
//////////////////////
while (readByteSum < amrDataLen) {
  serial[0] = *(amrData + readByteSum);
#ifdef IF2
  mode = (Word16)(serial[0] >> 4);
#else
  mode = (Word16) ((serial[0] >> 3) & 0x0F);
#endif
  if(mode >= 0 && mode <= 8){
   readLen = block_size[mode] - 1;
   for (i = 1; i <= readLen; i++) {
    serial[i] = *(amrData + i + readByteSum);
   }
   frame++;
   readByteSum += (readLen + 1);
//            fprintf(stderr, " Decoding frame: %d,%d\r", frame,writeByteSum);
   D_IF_decode(st, serial, synth16, _good_frame);
   tempPt = reinterpret_cast<char*>(synth16);
   /**
    * TODO
    * 修改timestamp
    */
   if(isFirstTagHdr){
    isFirstTagHdr = false;
   }else{
    calculateTimeStamp(timeStamp);
   }

   flvTagHeaderSize = getFlvTagHeader(flvTagHeader,0);//获取tag header
   for(j = 0;j < flvTagHeaderSize;j++){
    *(wavData + j + writeByteSum) = *(flvTagHeader + j);//把tag header写入flv文件
   }
   writeByteSum += flvTagHeaderSize;

   flvTagDataFirstByteSize = getFlvTagDataFirstByte(flvTagDataFirstByte,0);//tagData的firstByte
   for(j = 0;j < flvTagDataFirstByteSize;j++){
    *(wavData + j + writeByteSum) = *(flvTagDataFirstByte + j);//把tagData的firstByte写入flv
   }
   writeByteSum += flvTagDataFirstByteSize;

   for (j = 0; j < writeLen; j++) {
    *(wavData + j + writeByteSum) = *(tempPt + j);
   }
   writeByteSum += writeLen;

   flvprevioustagsize = getPreviousTagSize(flvPreviousTagNum,0);//previousTagSize
   for(j = 0;j < flvprevioustagsize;j++){
    *(wavData + j + writeByteSum) = *(flvPreviousTagNum + j);
   }
   writeByteSum += flvprevioustagsize;
   fprintf(stderr, "previous tag size: %d\r", writeByteSum);
  }
}
return writeByteSum;
}

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