AAC ES流如何解碼播放

AAC原始流能讓ffmpeg軟解或系統硬解，最簡單的處理可在前面加上ADTS頭，那麼這個ADTS頭如何添加呢？其實就是七個字節，下面分享一個我使用的代碼樣例，每次傳遞數據都是以一個個sample爲單元的：

adts_header[7] = {0xff,0xf9,0x00,0x00,0x00,0x1f,0xfc};

     //AAC level
     switch(AAC_level)
     {
        case AUDIO_AACM:
       adts_header[2] |= (0x00 << 6)&0xc0;
       break;
          
        case AUDIO_AACL:
       adts_header[2] |= (0x01 << 6)&0xc0;
       break;
        
        case AUDIO_AACS:
       adts_header[2] |= (0x02 << 6)&0xc0;;
       break;
       
        default:/*use AACL*/
          adts_header[2] |= (0x01 << 6)&0xc0;
          break;
     }
     
     //sampling rate
     switch(AAC_sample_rate)
     {
        case SAMPLINGRATE_96000HZ:
       adts_header[2] |= (0x00 << 2)&0x3c;
       break;
          
        case SAMPLINGRATE_88200HZ:
       adts_header[2] |= (0x01 << 2)&0x3c;
       break;
        
        case SAMPLINGRATE_64000HZ:
       adts_header[2] |= (0x02 << 2)&0x3c;
       break;
          
        case SAMPLINGRATE_48000HZ:
       adts_header[2] |= (0x03 << 2)&0x3c;
       break;
          
        case SAMPLINGRATE_44100HZ:
       adts_header[2] |= (0x04 << 2)&0x3c;
       break;
     
        case SAMPLINGRATE_32000HZ:
       adts_header[2] |= (0x05 << 2)&0x3c;
       break;
     
        case SAMPLINGRATE_24000HZ:
       adts_header[2] |= (0x06 << 2)&0x3c;
       break;
          
        case SAMPLINGRATE_22050HZ:
       adts_header[2] |= (0x07 << 2)&0x3c;
       break;
          
        case SAMPLINGRATE_16000HZ:
       adts_header[2] |= (0x08 << 2)&0x3c;
       break;
     
        case SAMPLINGRATE_12000HZ:
       adts_header[2] |= (0x09 << 2)&0x3c;
       break;     
        
        case SAMPLINGRATE_11025HZ:
       adts_header[2] |= (0x0a << 2)&0x3c;
       break; 
        
        case SAMPLINGRATE_8000HZ:
       adts_header[2] |= (0x0b << 2)&0x3c;
       break;
          
        default:/*use 44100*/
       adts_header[2] |= (0x04 << 2)&0x3c;
       break;

     }
     
     
     //channels
     switch(AAC_channel_no)
     {
        case CHANNEL_NUMBER_1:
         adts_header[2] |= (0x01 >> 2)&0x01;
         adts_header[3] |= (0x01 << 6)&0xc0;
         break;
     
        case CHANNEL_NUMBER_2:
         adts_header[2] |= (0x02 >> 2)&0x01;
         adts_header[3] |= (0x02 << 6)&0xc0;
         break;
     
        case CHANNEL_NUMBER_3:
         adts_header[2] |= (0x03 >> 2)&0x01;
         adts_header[3] |= (0x03 << 6)&0xc0;
         break;
     
        case CHANNEL_NUMBER_4:
         adts_header[2] |= (0x04 >> 2)&0x01;
         adts_header[3] |= (0x04 << 6)&0xc0;;
         break;
     
        case CHANNEL_NUMBER_5:
         adts_header[2] |= (0x05 >> 2)&0x01;
         adts_header[3] |= (0x05 << 6)&0xc0;
         break;
     
        case CHANNEL_NUMBER_6:
         adts_header[2] |= (0x06 >> 2)&0x01;
         adts_header[3] |= (0x06 << 6)&0xc0;
         break;
     
        case CHANNEL_NUMBER_8:
         adts_header[2] |= (0x07 >> 2)&0x01;
         adts_header[3] |= (0x07 << 6)&0xc0;
         break;
     
        default:/*use number 2*/
         adts_header[2] |= (0x02 >> 2)&0x01;
         adts_header[3] |= (0x02 << 6)&0xc0;
         break;
     
     }
     
     adts_header[3] = adts_header[3] | ((AAC_adts_sample_size >> 11)& 0x3); 
     adts_header[4] = adts_header[4] | ((AAC_adts_sample_size >> 3) & 0xff); 
     adts_header[5] = adts_header[5] | (((AAC_adts_sample_size >> 0)& 0x07) << 5);