【已解决】FDK AAC 噪音求指导_问答

本帖最后由 ezreal_cs 于 2018-7-30 18:44 编辑

海思采用的是 I2S输入 48K 16位立体声.相关配置如下
[code]stAioAttr.enSamplerate = AUDIO_SAMPLE_RATE_48000;
stAioAttr.enBitwidth    = AUDIO_BIT_WIDTH_16;
stAioAttr.enWorkmode    = AIO_MODE_I2S_SLAVE;
stAioAttr.enSoundmode = AUDIO_SOUND_MODE_STEREO;
stAioAttr.u32EXFlag    = 0;
stAioAttr.u32FrmNum    = 30;
stAioAttr.u32PtNumPerFrm = SAMPLE_AUDIO_PTNUMPERFRM;  //320
stAioAttr.u32ClkChnCnt = 2;
stAioAttr.u32ChnCnt    = 2;
stAioAttr.u32ClkSel    = 0;[/code]

获取音频数据并保存为文件的代码如下:
[code]for(i=0; i fwrite(stFrame.pVirAddr[0]+i,  1 ,2 , fileFD);
fwrite(stFrame.pVirAddr[1]+i,  1 ,2 , fileFD);
}[/code]

此时获取到的PCM文件在PC上播放正常,左右声道都很正确,, (附件中的  xxx.pcm 文件).

然后将获取到的音频数据进行FDK AAC编码后在声音稍大些的时候会有爆音.  无论是海思芯片上还是PC上都试过,效果一样.

FDK AAC相关代码照搬[url]https://github.com/mstorsjo/fdk-aac/blob/master/aac-enc.c[/url]修改而来.
[code]while (1) {
      AACENC_BufDesc in_buf = { 0 }, out_buf = { 0 };
      AACENC_InArgs in_args = { 0 };
      AACENC_OutArgs out_args = { 0 };
      int in_identifier = IN_AUDIO_DATA;
      int in_size, in_elem_size;
      int out_identifier = OUT_BITSTREAM_DATA;
      int out_size, out_elem_size;
      int read, i;
      void *in_ptr, *out_ptr;
      uint8_t outbuf[20480];
      AACENC_ERROR err;

      //read = wav_read_data(wav, input_buf, input_size);
      read = fread( input_buf, 1, 640, inFd );

      if( read <= 0 )
      {
         printf("xxxxx文件读完了！！！\n");
         exit(-1);
      }

      for (i = 0; i < read/2; i++) {
         const uint8_t* in = &input_buf[2*i];
         convert_buf = in[0] | (in[1] << 8);
      }
      if (read <= 0) {
         in_args.numInSamples = -1;
      } else {
         in_ptr = convert_buf;
         in_size = read;
         in_elem_size = 2;

         in_args.numInSamples = read/2;
         in_buf.numBufs = 1;
         in_buf.bufs = &in_ptr;
         in_buf.bufferIdentifiers = &in_identifier;
         in_buf.bufSizes = &in_size;
         in_buf.bufElSizes = &in_elem_size;
      }
      out_ptr = outbuf;
      out_size = sizeof(outbuf);
      out_elem_size = 1;
      out_buf.numBufs = 1;
      out_buf.bufs = &out_ptr;
      out_buf.bufferIdentifiers = &out_identifier;
      out_buf.bufSizes = &out_size;
      out_buf.bufElSizes = &out_elem_size;

      if ((err = aacEncEncode(_encoder, &in_buf, &out_buf, &in_args, &out_args)) != AACENC_OK) {
         if (err == AACENC_ENCODE_EOF)
            break;
         fprintf(stderr, "Encoding failed\n");
         return;
      }
      if (out_args.numOutBytes == 0)
         continue;
      fwrite(outbuf, 1, out_args.numOutBytes, outFd);
}[/code]
尝试改过 fdk-aac的AACENC_BufDesc 结构配置,以即初始化的配置..  但都不行
求大神指点下了.. 附件是我的工程代码, CMAKE写的, (fdk-aac 是用的静态库 ubuntu 16.04 64bit)
直接
[code]cmake .
make[/code]
可以生成 pcmToAAC 文件, 运行会读取 xxx.pcm文件并编码生成 xxx.aac.
不知道哪位大神调过FDK AAC,望指点.
附件：pcmToAAC.tar.gz

问题已经找到...
用海思mpp里的sample配置时, stAioAttr.u32PtNumPerFrm = SAMPLE_AUDIO_PTNUMPERFRM;  //320
就是每个数据包里320个数据.
在FDK AAC中有个配置
[code]  AACENC_GRANULE_LENGTH          = 0x0105,  /*!< Core encoder (AAC) audio frame length in samples:
                                                - 1024: Default configuration.
                                                - 512: Default LD/ELD configuration.
                                                - 480: Optional length in LD/ELD configuration. */[/code]

所以按每取一个音频包就给AAC编码时会出现数据匹配不上,导致破音.
解决办法也简单,改AAC编码器配置或海思采样数都可以解决

【已解决】FDK AAC 噪音求指导

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