interf_dec.c

ffmpeg源码分析

         if ( *stream & 0x1 )
            param[ * mask] = ( short )( param[ * mask] + *( mask + 1 ) );
         mask += 2;

         if ( j % 8 )
            *stream >>= 1;
         else
            stream++;
      }
      *frame_type = RX_SPEECH_GOOD;
   }
   else if ( mode == MR59 ) {
      mask = order_MR59;

      for ( j = 5; j < 123; j++ ) {
         if ( *stream & 0x1 )
            param[ * mask] = ( short )( param[ * mask] + *( mask + 1 ) );
         mask += 2;

         if ( j % 8 )
            *stream >>= 1;
         else
            stream++;
      }
      *frame_type = RX_SPEECH_GOOD;
   }
   else if ( mode == MR67 ) {
      mask = order_MR67;

      for ( j = 5; j < 139; j++ ) {
         if ( *stream & 0x1 )
            param[ * mask] = ( short )( param[ * mask] + *( mask + 1 ) );
         mask += 2;

         if ( j % 8 )
            *stream >>= 1;
         else
            stream++;
      }
      *frame_type = RX_SPEECH_GOOD;
   }
   else if ( mode == MR74 ) {
      mask = order_MR74;

      for ( j = 5; j < 153; j++ ) {
         if ( *stream & 0x1 )
            param[ * mask] = ( short )( param[ * mask] + *( mask + 1 ) );
         mask += 2;

         if ( j % 8 )
            *stream >>= 1;
         else
            stream++;
      }
      *frame_type = RX_SPEECH_GOOD;
   }
   else if ( mode == MR795 ) {
      mask = order_MR795;

      for ( j = 5; j < 164; j++ ) {
         if ( *stream & 0x1 )
            param[ * mask] = ( short )( param[ * mask] + *( mask + 1 ) );
         mask += 2;

         if ( j % 8 )
            *stream >>= 1;
         else
            stream++;
      }
      *frame_type = RX_SPEECH_GOOD;
   }
   else if ( mode == MR102 ) {
      mask = order_MR102;

      for ( j = 5; j < 209; j++ ) {
         if ( *stream & 0x1 )
            param[ * mask] = ( short )( param[ * mask] + *( mask + 1 ) );
         mask += 2;

         if ( j % 8 )
            *stream >>= 1;
         else
            stream++;
      }
      *frame_type = RX_SPEECH_GOOD;
   }
   else if ( mode == MR122 ) {
      mask = order_MR122;

      for ( j = 5; j < 249; j++ ) {
         if ( *stream & 0x1 )
            param[ * mask] = ( short )( param[ * mask] + *( mask + 1 ) );
         mask += 2;

         if ( j % 8 )
            *stream >>= 1;
         else
            stream++;
      }
      *frame_type = RX_SPEECH_GOOD;
   }
   else
      *frame_type = RX_SPEECH_BAD;
   return mode;
}
#endif
#endif

/*
 * Decoder_Interface_reset
 *
 *
 * Parameters:
 *    st                O: state struct
 *
 * Function:
 *    Reset homing frame counter
 *
 * Returns:
 *    void
 */
void Decoder_Interface_reset( dec_interface_State *st )
{
   st->reset_flag_old = 1;
   st->prev_ft = RX_SPEECH_GOOD;
   st->prev_mode = MR475;   /* minimum bitrate */
}


/*
 * Decoder_Interface_init
 *
 *
 * Parameters:
 *    void
 *
 * Function:
 *    Allocates state memory and initializes state memory
 *
 * Returns:
 *    success           : pointer to structure
 *    failure           : NULL
 */
void * Decoder_Interface_init( void )
{
   dec_interface_State * s;

   /* allocate memory */
   if ( ( s = ( dec_interface_State * ) malloc( sizeof( dec_interface_State ) ) ) ==
         NULL ) {
      fprintf( stderr, "Decoder_Interface_init: "
            "can not malloc state structure\n" );
      return NULL;
   }
   s->decoder_State = Speech_Decode_Frame_init( );

   if ( s->decoder_State == NULL ) {
      free( s );
      return NULL;
   }
   Decoder_Interface_reset( s );
   return s;
}


/*
 * Decoder_Interface_exit
 *
 *
 * Parameters:
 *    state                I: state structure
 *
 * Function:
 *    The memory used for state memory is freed
 *
 * Returns:
 *    Void
 */
void Decoder_Interface_exit( void *state )
{
   dec_interface_State * s;
   s = ( dec_interface_State * )state;

   /* free memory */
   Speech_Decode_Frame_exit(s->decoder_State );
   free( s );
   s = NULL;
   state = NULL;
}


/*
 * Decoder_Interface_Decode
 *
 *
 * Parameters:
 *    st                B: state structure
 *    bits              I: bit stream
 *    synth             O: synthesized speech
 *    bfi               I: bad frame indicator
 *
 * Function:
 *    Decode bit stream to synthesized speech
 *
 * Returns:
 *    Void
 */
void Decoder_Interface_Decode( void *st,

#ifndef ETSI
      UWord8 *bits,

#else
      Word16 *bits,
#endif

      Word16 *synth, int bfi)
{
   enum Mode mode;   /* AMR mode */

#ifndef ETSI
   enum Mode speech_mode = MR475;   /* speech mode */
#endif

   Word16 prm[PRMNO_MR122];   /* AMR parameters */

   enum RXFrameType frame_type;   /* frame type */
   dec_interface_State * s;   /* pointer to structure */

   const Word16 *homing;   /* pointer to homing frame */
   Word16 homingSize;   /* frame size for homing frame */
   Word32 i;   /* counter */
   Word32 resetFlag = 1;   /* homing frame */

#ifndef ETSI
#ifndef IF2
   Word16 q_bit;
#endif
#endif

   s = ( dec_interface_State * )st;

#ifndef ETSI

   /*
    * extract mode information and frametype,
    * octets to parameters
    */
#ifdef IF2
   mode = Decoder3GPP( prm, bits, &frame_type, &speech_mode );
#else
   mode = DecoderMMS( prm, bits, &frame_type, &speech_mode, &q_bit );
   if (!bfi)	bfi = 1 - q_bit;
#endif

   if ( bfi == 1 ) {
      if ( mode <= MR122 ) {
         frame_type = RX_SPEECH_BAD;
      }
      else if ( frame_type != RX_NO_DATA ) {
         frame_type = RX_SID_BAD;
         mode = s->prev_mode;
      }
   } else {
       if ( frame_type == RX_SID_FIRST || frame_type == RX_SID_UPDATE) {
           mode = speech_mode;
       }
       else if ( frame_type == RX_NO_DATA ) {
           mode = s->prev_mode;
       }
       /*
        * if no mode information
        * guess one from the previous frame
        */
       if ( frame_type == RX_SPEECH_BAD ) {
          mode = s->prev_mode;
          if ( s->prev_ft >= RX_SID_FIRST ) {
             frame_type = RX_SID_BAD;
          }
       }
   }
#else
   bfi = 0;
   frame_type = bits[0];

   switch ( frame_type ) {
      case 0:
         frame_type = RX_SPEECH_GOOD;
         mode = bits[245];
         Bits2Prm( mode, &bits[1], prm );
         break;

      case 1:
         frame_type = RX_SID_FIRST;
         mode = bits[245];
         break;

      case 2:
         frame_type = RX_SID_UPDATE;
         mode = bits[245];
         Bits2Prm( MRDTX, &bits[1], prm );
         break;

      case 3:
         frame_type = RX_NO_DATA;
         mode = s->prev_mode;
         break;
   }
#endif

   /* test for homing frame */
   if ( s->reset_flag_old == 1 ) {
      switch ( mode ) {
         case MR122:
            homing = dhf_MR122;
            homingSize = 18;
            break;

         case MR102:
            homing = dhf_MR102;
            homingSize = 12;
            break;

         case MR795:
            homing = dhf_MR795;
            homingSize = 8;
            break;

         case MR74:
            homing = dhf_MR74;
            homingSize = 7;
            break;

         case MR67:
            homing = dhf_MR67;
            homingSize = 7;
            break;

         case MR59:
            homing = dhf_MR59;
            homingSize = 7;
            break;

         case MR515:
            homing = dhf_MR515;
            homingSize = 7;
            break;

         case MR475:
            homing = dhf_MR475;
            homingSize = 7;
            break;

         default:
            homing = NULL;
            homingSize = 0;
            break;
      }

      for ( i = 0; i < homingSize; i++ ) {
         resetFlag = prm[i] ^ homing[i];

         if ( resetFlag )
            break;
      }
   }

   if ( ( resetFlag == 0 ) && ( s->reset_flag_old != 0 ) ) {
      for ( i = 0; i < 160; i++ ) {
         synth[i] = EHF_MASK;
      }
   }
   else
      Speech_Decode_Frame( s->decoder_State, mode, prm, frame_type, synth );

   if ( s->reset_flag_old == 0 ) {
      /* check whole frame */
      switch ( mode ) {
         case MR122:
            homing = dhf_MR122;
            homingSize = PRMNO_MR122;
            break;

         case MR102:
            homing = dhf_MR102;
            homingSize = PRMNO_MR102;
            break;

         case MR795:
            homing = dhf_MR795;
            homingSize = PRMNO_MR795;
            break;

         case MR74:
            homing = dhf_MR74;
            homingSize = PRMNO_MR74;
            break;

         case MR67:
            homing = dhf_MR67;
            homingSize = PRMNO_MR67;
            break;

         case MR59:
            homing = dhf_MR59;
            homingSize = PRMNO_MR59;
            break;

         case MR515:
            homing = dhf_MR515;
            homingSize = PRMNO_MR515;
            break;

         case MR475:
            homing = dhf_MR475;
            homingSize = PRMNO_MR475;
            break;

         default:
            homing = NULL;
            homingSize = 0;
      }

      for ( i = 0; i < homingSize; i++ ) {
         resetFlag = prm[i] ^ homing[i];

         if ( resetFlag )
            break;
      }
   }

   /* reset decoder if current frame is a homing frame */
   if ( resetFlag == 0 ) {
      Speech_Decode_Frame_reset( s->decoder_State );
   }
   s->reset_flag_old = !resetFlag;
   s->prev_ft = frame_type;
   s->prev_mode = mode;
}