AMR 编码 PCM & WAV （opencore-amr-0.1.5）

AMR编码基于第三方opencore-amr-0.1.5库

支持PCM2AMR，WAV2AMR

test目录下：pcm2amr.c pcm2amr.c，linux环境下 调试通过，准备移植到安卓手机

资源下载链接：http://download.csdn.net/detail/yuanchunsi/9917689

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pcm2amr.h代码如下：

#ifndef pcm2amr_h
#define pcm2amr_h

#include <stdio.h>
#include <stdint.h>
#include <interf_enc.h>
#include <unistd.h>
#include <stdlib.h>
//#include "wavreader.h"


#define AMR_MAGIC_NUMBER "#!AMR\n"
 
#define PCM_FRAME_SIZE 160 // 8khz 8000*0.02=160
#define MAX_AMR_FRAME_SIZE 32
#define AMR_FRAME_COUNT_PER_SECOND 50
//int amrEncodeMode[] = {4750, 5150, 5900, 6700, 7400, 7950, 10200, 12200}; // amr 编码方式
 
typedef struct
{
         char chChunkID[4];
         int nChunkSize;
}XCHUNKHEADER;
 
typedef struct
{
         short nFormatTag;
         short nChannels;
         int nSamplesPerSec;
         int nAvgBytesPerSec;
         short nBlockAlign;
         short nBitsPerSample;
}WAVEFORMAT;
 
typedef struct
{
         short nFormatTag;
         short nChannels;
         int nSamplesPerSec;
         int nAvgBytesPerSec;
         short nBlockAlign;
         short nBitsPerSample;
         short nExSize;
}WAVEFORMATX;
 
typedef struct
{
         char chRiffID[4];
         int nRiffSize;
         char chRiffFormat[4];
}RIFFHEADER;
 
typedef struct
{
         char chFmtID[4];
         int nFmtSize;
         WAVEFORMAT wf;
}FMTBLOCK;
 
// WAVE音频采样频率是8khz
// 音频样本单元数 = 8000*0.02 = 160 (由采样频率决定)
// 声道数 1 : 160
//        2 : 160*2 = 320
// bps决定样本(sample)大小
// bps = 8 --> 8位 unsigned char
//       16 --> 16位 unsigned short
//int EncodeWAVEFileToAMRFile(const char* pchWAVEFilename, const char* pchAMRFileName, int nChannels, int nBitsPerSample);
 
// 将AMR文件解码成WAVE文件
//int DecodeAMRFileToWAVEFile(const char* pchAMRFileName, const char* pchWAVEFilename);
 
#endif

pcm2amr.c代码如下：
#include "pcm2amr.h"

// 从WAVE文件中跳过WAVE文件头，直接到PCM音频数据
void SkipToPCMAudioData(FILE* fpwave)
{
  RIFFHEADER riff;
  FMTBLOCK fmt;
  XCHUNKHEADER chunk;
  WAVEFORMATX wfx;
  int bDataBlock = 0;

  // 1. 读RIFF头
  fread(&riff, 1, sizeof(RIFFHEADER), fpwave);

  // 2. 读FMT块 - 如果 fmt.nFmtSize>16 说明需要还有一个附属大小没有读
  fread(&chunk, 1, sizeof(XCHUNKHEADER), fpwave);
  if ( chunk.nChunkSize>16 )
  {
    fread(&wfx, 1, sizeof(WAVEFORMATX), fpwave);
  }
  else
  {
    memcpy(fmt.chFmtID, chunk.chChunkID, 4);
    fmt.nFmtSize = chunk.nChunkSize;
    fread(&fmt.wf, 1, sizeof(WAVEFORMAT), fpwave);
  }

  // 3.转到data块 - 有些还有fact块等。
  while(!bDataBlock)
  {
    fread(&chunk, 1, sizeof(XCHUNKHEADER), fpwave);
    if ( !memcmp(chunk.chChunkID, "data", 4) )
    {
      bDataBlock = 1;
      break;
    }
    // 因为这个不是data块,就跳过块数据
    fseek(fpwave, chunk.nChunkSize, SEEK_CUR);
  }
 
}

// 从WAVE文件读一个完整的PCM音频帧
// 返回值: 0-错误 >0: 完整帧大小
int ReadPCMFrame(short speech[], FILE* fpwave, int nChannels, int nBitsPerSample)
{
  int nRead = 0;
  int x = 0, y=0;
  unsigned short ush1=0, ush2=0, ush=0;

  // 原始PCM音频帧数据
  unsigned char pcmFrame_8b1[PCM_FRAME_SIZE];
  unsigned char pcmFrame_8b2[PCM_FRAME_SIZE<<1];
  unsigned short pcmFrame_16b1[PCM_FRAME_SIZE];
  unsigned short pcmFrame_16b2[PCM_FRAME_SIZE<<1];

  if (nBitsPerSample==8 && nChannels==1)
  {
    nRead = fread(pcmFrame_8b1, (nBitsPerSample/8), PCM_FRAME_SIZE*nChannels, fpwave);
    for(x=0; x<PCM_FRAME_SIZE; x++)
    {
      speech[x] =(short)((short)pcmFrame_8b1[x] << 7);
    }
  }
  else
    if (nBitsPerSample==8 && nChannels==2)
    {
      nRead = fread(pcmFrame_8b2, (nBitsPerSample/8), PCM_FRAME_SIZE*nChannels, fpwave);
      for( x=0, y=0; y<PCM_FRAME_SIZE; y++,x+=2 )
      {
        // 1 - 取两个声道之左声道
        speech[y] =(short)((short)pcmFrame_8b2[x+0] << 7);
        // 2 - 取两个声道之右声道
        //speech[y] =(short)((short)pcmFrame_8b2[x+1] << 7);
        // 3 - 取两个声道的平均值
        //ush1 = (short)pcmFrame_8b2[x+0];
        //ush2 = (short)pcmFrame_8b2[x+1];
        //ush = (ush1 + ush2) >> 1;
        //speech[y] = (short)((short)ush << 7);
      }
    }
    else
      if (nBitsPerSample==16 && nChannels==1)
      {
        nRead = fread(pcmFrame_16b1, (nBitsPerSample/8), PCM_FRAME_SIZE*nChannels, fpwave);
        if (nRead == PCM_FRAME_SIZE*nChannels) {
          for(x=0; x<PCM_FRAME_SIZE; x++)
          {
            speech[x] = (short)pcmFrame_16b1[x+0];
          }
        }
      }
      else
        if (nBitsPerSample==16 && nChannels==2)
        {
          nRead = fread(pcmFrame_16b2, (nBitsPerSample/8), PCM_FRAME_SIZE*nChannels, fpwave);
          for( x=0, y=0; y<PCM_FRAME_SIZE; y++,x+=2 )
          {
            //speech[y] = (short)pcmFrame_16b2[x+0];
            speech[y] = (short)((int)((int)pcmFrame_16b2[x+0] + (int)pcmFrame_16b2[x+1])) >> 1;
          }
        }

  if (nRead != PCM_FRAME_SIZE*nChannels)  return -1;
  printf("ReadPCMFrame done\n");
  return nRead;
}

// WAVE音频采样频率是8khz
// 音频样本单元数 = 8000*0.02 = 160 (由采样频率决定)
// 声道数 1 : 160
//        2 : 160*2 = 320
// bps决定样本(sample)大小
// bps = 8 --> 8位 unsigned char
//       16 --> 16位 unsigned short

//int EncodeWAVEFileToAMRFile(const char* pchWAVEFilename, const char* pchAMRFileName, int nChannels, int nBitsPerSample)
int main ()
{
  FILE* fpwave;
  FILE* fpamr;

  /* input speech vector */
  short speech[160];

  /* counters */
  int byte_counter, frames = 0, bytes = 0;

  /* pointer to encoder state structure */
  int *enstate;

  /* requested mode */
  enum Mode req_mode = MR122;
  int dtx = 0;

  /* bitstream filetype */
  unsigned char amrFrame[MAX_AMR_FRAME_SIZE];
#if 0
//WAV和PCM数据区别仅仅是wav多了数据头
  fpwave = fopen("./input.wav", "rb");
#else
  fpwave = fopen("./audio.pcm", "rb");
#endif
  if (fpwave == NULL)
  {
    return 0;
  }

  // 创建并初始化amr文件
  fpamr = fopen("./out.amr", "wb");
  if (fpamr == NULL)
  {
    fclose(fpwave);
    return 0;
  }
  /* write magic number to indicate single channel AMR file storage format */
  bytes = fwrite(AMR_MAGIC_NUMBER, sizeof(char), strlen(AMR_MAGIC_NUMBER), fpamr);

#if 0
  /* skip to pcm audio data*/
  //跳过WAV数据包头既是PCM原始数据
  SkipToPCMAudioData(fpwave);
#endif
  enstate = Encoder_Interface_init(dtx);

  while(1)
  {
    // read one pcm frame
    //if (!ReadPCMFrame(speech, fpwave, nChannels, nBitsPerSample)) break;
    if (-1 == ReadPCMFrame(speech, fpwave, 1, 16)) {
      //printf("ReadPCMFrame failed\n");
      break;
    }

    frames++;

    /* call encoder */
    byte_counter = Encoder_Interface_Encode(enstate, req_mode, speech, amrFrame, 0);
    printf("byte_counter == %d\n",byte_counter);

    bytes += byte_counter;
    fwrite(amrFrame, sizeof (unsigned char), byte_counter, fpamr );
  }

  Encoder_Interface_exit(enstate);

  fclose(fpamr);
  fclose(fpwave);

  return frames;
}

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