G711转AAC代码总结【转】

来自：http://blog.csdn.net/qq_24551315/article/details/51134999

思路: 将G711转为PCM , 然后将PCM数据转为AAC,

G711转为PCM,可以使用上一篇中讲到的方式, 而PCM转AAC(ADTS),采用的是faac这个开源库

这里只讲怎么实现, 了解更详细的内容,则需要自己查找学习了.

直接上代码.

 JNIEXPORT jint JNICALL Java_com_ff_aacdemo_jni_G711Coder_g711ToAAC
   (JNIEnv *env, jobject obj){
     unsigned long sampleRate = 8000;//采样率
     unsigned int channels = 1;//通道数
     unsigned int pcmBitSize = 16;// 量化位数

     long inputSamples;
     long maxOutputBytes;
     faacEncHandle codeHandle = faacEncOpen(sampleRate, channels, &inputSamples, &maxOutputBytes);
     int maxInputBytes = inputSamples * pcmBitSize / 8;
     LOGD("inputSamples = %ld, maxOutputBytes = %ld, maxInputBytes = %d", inputSamples, maxOutputBytes, maxInputBytes);

     faacEncConfigurationPtr pConfigPtr = faacEncGetCurrentConfiguration(codeHandle);
     pConfigPtr->inputFormat = FAAC_INPUT_16BIT;//输入数据类型
     pConfigPtr->outputFormat = 1; //0-Raw ; 1-ADTS
     pConfigPtr->useTns= 0;//瞬时噪声定形(temporal noise shaping，TNS)滤波器
     pConfigPtr->useLfe= 0;//低频效果
     pConfigPtr->aacObjectType= LOW; //编码类型
     pConfigPtr->shortctl=SHORTCTL_NORMAL;
     pConfigPtr->quantqual=50; // 编码质量
     pConfigPtr->mpegVersion = MPEG2;
     faacEncSetConfiguration(codeHandle, pConfigPtr);

     int m_nMaxInputBytes = inputSamples * pcmBitSize / 8;
     char pbPCMBuffer[m_nMaxInputBytes]; // 读取PCM数据
     char pbAACBuffer[maxOutputBytes];
     LOGD("g711topcm m_nMaxInputBytes = %d", m_nMaxInputBytes);
     LOGD("g711topcm maxOutputBytes = %d", maxOutputBytes);

     FILE* fpIn = fopen("/storage/emulated/0/t/pcm_to_g711.g711","rb");
     FILE* fpOut = fopen("/storage/emulated/0/t/pcm_to_g711.aac", "wb");

     size_t g711_BufferSize = m_nMaxInputBytes / 2;
     LOGD("g711topcm g711_BufferSize = %d", g711_BufferSize);
     char g711_Buffer[g711_BufferSize];//G711->PCM后,体积会变为原来的两倍,而PCM一次编码需要的最小字节数为m_nMaxInputBytes(如果小于它,编码后的数据不正常)
     size_t len;

     LOGD("********************************");
     while((len = fread(g711_Buffer, 1, g711_BufferSize, fpIn)) > 0){
         LOGD("g711topcm length = %d", len);
         char pcmBuffer[len];
         int pcmbufsize = g711_decode(pcmBuffer, g711_Buffer, len); // g711 -> pcm  (g711 转为 pcm 后其体积会增加一倍)
         LOGD("g711topcm pcmbufsize = %d", pcmbufsize);

         // pcm -> aac
         int inputSamples = pcmbufsize / (pcmBitSize / 8);
         LOGD("g711topcm inputSamples = %d", inputSamples);
         int nRetVal = faacEncEncode(codeHandle, (int*) pcmBuffer, inputSamples, pbAACBuffer, maxOutputBytes);
         LOGD("g711topcm nRetVal = %d", nRetVal);
         fwrite(pbAACBuffer, 1, nRetVal, fpOut);
         LOGD("----------------------------------");
     }
     fclose(fpIn);
     fclose(fpOut);
     faacEncClose(codeHandle);
     return 0;
 }

如果对AAC 的编解码不知道怎么弄的话, 可以看下一篇, 使用 faac, faad  实现 AAC 与 PCM 的互转
参考文章

http://blog.csdn.net/jwzhangjie/article/details/8782656
http://www.myexception.cn/program/1833150.html
http://iask.sina.com.cn/b/10699938.html
http://www.zhihu.com/question/20035259?utm_campaign=rss&utm_medium=rss&utm_source=rss&utm_content=title