コード例 #1
0
ファイル: layer12.c プロジェクト: Eaeth/myNCCL
/*
 * NAME:	layer->I()
 * DESCRIPTION:	decode a single Layer I frame
 */
int mad_layer_I(struct mad_stream *stream, struct mad_frame *frame)
{
  struct mad_header *header = &frame->header;
  unsigned int nch, bound, ch, s, sb, nb;
  unsigned char allocation[2][32], scalefactor[2][32];

  nch = MAD_NCHANNELS(header);

  bound = 32;
  if (header->mode == MAD_MODE_JOINT_STEREO) {
    header->flags |= MAD_FLAG_I_STEREO;
    bound = 4 + header->mode_extension * 4;
  }

  /* check CRC word */

  if (header->flags & MAD_FLAG_PROTECTION) {
    header->crc_check =
      mad_bit_crc(stream->ptr, 4 * (bound * nch + (32 - bound)),
		  header->crc_check);

    if (header->crc_check != header->crc_target &&
	!(frame->options & MAD_OPTION_IGNORECRC)) {
      stream->error = MAD_ERROR_BADCRC;
      return -1;
    }
  }

  /* decode bit allocations */

  for (sb = 0; sb < bound; ++sb) {
    for (ch = 0; ch < nch; ++ch) {
      nb = mad_bit_read(&stream->ptr, 4);

      if (nb == 15) {
	stream->error = MAD_ERROR_BADBITALLOC;
	return -1;
      }

      allocation[ch][sb] = nb ? nb + 1 : 0;
    }
  }

  for (sb = bound; sb < 32; ++sb) {
    nb = mad_bit_read(&stream->ptr, 4);

    if (nb == 15) {
      stream->error = MAD_ERROR_BADBITALLOC;
      return -1;
    }

    allocation[0][sb] =
    allocation[1][sb] = nb ? nb + 1 : 0;
  }

  /* decode scalefactors */

  for (sb = 0; sb < 32; ++sb) {
    for (ch = 0; ch < nch; ++ch) {
      if (allocation[ch][sb]) {
	scalefactor[ch][sb] = mad_bit_read(&stream->ptr, 6);

# if defined(OPT_STRICT)
	/*
	 * Scalefactor index 63 does not appear in Table B.1 of
	 * ISO/IEC 11172-3. Nonetheless, other implementations accept it,
	 * so we only reject it if OPT_STRICT is defined.
	 */
	if (scalefactor[ch][sb] == 63) {
	  stream->error = MAD_ERROR_BADSCALEFACTOR;
	  return -1;
	}
# endif
      }
    }
  }

  /* decode samples */

  for (s = 0; s < 12; ++s) {
    for (sb = 0; sb < bound; ++sb) {
      for (ch = 0; ch < nch; ++ch) {
	nb = allocation[ch][sb];
	frame->sbsample[ch][s][sb] = nb ?
	  mad_f_mul(I_sample(&stream->ptr, nb),
		    sf_table[scalefactor[ch][sb]]) : 0;
      }
    }

    for (sb = bound; sb < 32; ++sb) {
      if ((nb = allocation[0][sb])) {
	mad_fixed_t sample;

	sample = I_sample(&stream->ptr, nb);

	for (ch = 0; ch < nch; ++ch) {
	  frame->sbsample[ch][s][sb] =
	    mad_f_mul(sample, sf_table[scalefactor[ch][sb]]);
	}
      }
      else {
	for (ch = 0; ch < nch; ++ch)
	  frame->sbsample[ch][s][sb] = 0;
      }
    }
  }

  return 0;
}
コード例 #2
0
ファイル: layer12.cpp プロジェクト: androllen/wpaudio
int mad_layer_I(struct mad_stream *stream, struct mad_frame *frame)
{
  struct mad_header *header = &frame->header;
  unsigned int nch, bound, ch, s, sb, nb;
  unsigned char allocation[2][32], scalefactor[2][32];

  nch = MAD_NCHANNELS(header);

  bound = 32;
  if (header->mode == MAD_MODE_JOINT_STEREO) {
    header->flags |= MAD_FLAG_I_STEREO;
    bound = 4 + header->mode_extension * 4;
  }


  if (header->flags & MAD_FLAG_PROTECTION) {
    header->crc_check =
      mad_bit_crc(stream->ptr, 4 * (bound * nch + (32 - bound)),
		  header->crc_check);

    if (header->crc_check != header->crc_target &&
	!(frame->options & MAD_OPTION_IGNORECRC)) {
      stream->error = MAD_ERROR_BADCRC;
      return -1;
    }
  }


  for (sb = 0; sb < bound; ++sb) {
    for (ch = 0; ch < nch; ++ch) {
      nb = mad_bit_read(&stream->ptr, 4);

      if (nb == 15) {
	stream->error = MAD_ERROR_BADBITALLOC;
	return -1;
      }

      allocation[ch][sb] = nb ? nb + 1 : 0;
    }
  }

  for (sb = bound; sb < 32; ++sb) {
    nb = mad_bit_read(&stream->ptr, 4);

    if (nb == 15) {
      stream->error = MAD_ERROR_BADBITALLOC;
      return -1;
    }

    allocation[0][sb] =
    allocation[1][sb] = nb ? nb + 1 : 0;
  }


  for (sb = 0; sb < 32; ++sb) {
    for (ch = 0; ch < nch; ++ch) {
      if (allocation[ch][sb]) {
	scalefactor[ch][sb] = (unsigned char)(mad_bit_read(&stream->ptr, 6));

	if (scalefactor[ch][sb] == 63) {
	  stream->error = MAD_ERROR_BADSCALEFACTOR;
	  return -1;
	}
      }
    }
  }


  for (s = 0; s < 12; ++s) {
    for (sb = 0; sb < bound; ++sb) {
      for (ch = 0; ch < nch; ++ch) {
	nb = allocation[ch][sb];
	frame->sbsample[ch][s][sb] = nb ?
	  mad_f_mul(I_sample(&stream->ptr, nb),
		    sf_table[scalefactor[ch][sb]]) : 0;
      }
    }

    for (sb = bound; sb < 32; ++sb) {
      if ((nb = allocation[0][sb])) {
	mad_fixed_t sample;

	sample = I_sample(&stream->ptr, nb);

	for (ch = 0; ch < nch; ++ch) {
	  frame->sbsample[ch][s][sb] =
	    mad_f_mul(sample, sf_table[scalefactor[ch][sb]]);
	}
      }
      else {
	for (ch = 0; ch < nch; ++ch)
	  frame->sbsample[ch][s][sb] = 0;
      }
    }
  }

  return 0;
}