180 lines
5.7 KiB
C
180 lines
5.7 KiB
C
/*****************************************************************************
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**
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** ITU-T G.722.1 (2005-05) - Fixed point implementation for main body and Annex C
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** > Software Release 2.1 (2008-06)
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** (Simple repackaging; no change from 2005-05 Release 2.0 code)
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**
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** © 2004 Polycom, Inc.
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**
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** All rights reserved.
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**
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*****************************************************************************/
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/*****************************************************************************
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* Filename: rmlt_coefs_to_samples.c
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*
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* Purpose: Convert Reversed MLT (Modulated Lapped Transform)
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* Coefficients to Samples
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*
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* The "Reversed MLT" is an overlapped block transform which uses
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* even symmetry * on the left, odd symmetry on the right and a
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* Type IV DCT as the block transform. * It is thus similar to a
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* MLT which uses odd symmetry on the left, even symmetry * on the
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* right and a Type IV DST as the block transform. In fact, it is
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* equivalent * to reversing the order of the samples, performing
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* an MLT and then negating all * the even-numbered coefficients.
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*
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*****************************************************************************/
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/***************************************************************************
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Include files
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***************************************************************************/
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#include "defs.h"
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#include "tables.h"
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#include "count.h"
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/***************************************************************************
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Function: rmlt_coefs_to_samples
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Syntax: void rmlt_coefs_to_samples(Word16 *coefs,
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Word16 *old_samples,
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Word16 *out_samples,
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Word16 dct_length,
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Word16 mag_shift)
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inputs: Word16 *coefs
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Word16 *old_samples
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Word16 dct_length
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Word16 mag_shift
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outputs: Word16 *out_samples
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Description: Converts the mlt_coefs to samples
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Design Notes:
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WMOPS: 7kHz | 24kbit | 32kbit
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-------|--------------|----------------
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AVG | 1.91 | 1.91
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-------|--------------|----------------
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MAX | 1.91 | 1.91
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-------|--------------|----------------
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14kHz | 24kbit | 32kbit | 48kbit
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-------|--------------|----------------|----------------
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AVG | 3.97 | 3.97 | 3.97
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-------|--------------|----------------|----------------
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MAX | 3.97 | 3.97 | 3.97
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-------|--------------|----------------|----------------
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***************************************************************************/
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void rmlt_coefs_to_samples(Word16 *coefs,
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Word16 *old_samples,
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Word16 *out_samples,
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Word16 dct_length,
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Word16 mag_shift)
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{
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Word16 index, vals_left;
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Word16 new_samples[MAX_DCT_LENGTH];
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Word16 *new_ptr, *old_ptr;
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Word16 *win_new, *win_old;
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Word16 *out_ptr;
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Word16 half_dct_size;
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Word32 sum;
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half_dct_size = shr_nocheck(dct_length,1);
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/* Perform a Type IV (inverse) DCT on the coefficients */
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dct_type_iv_s(coefs, new_samples, dct_length);
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test();
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if (mag_shift > 0)
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{
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for(index=0;index<dct_length;index++)
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{
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new_samples[index] = shr_nocheck(new_samples[index],mag_shift);
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move16();
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}
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}
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else
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{
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test();
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if (mag_shift < 0)
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{
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mag_shift = negate(mag_shift);
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for(index=0;index<dct_length;index++)
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{
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new_samples[index] = shl_nocheck(new_samples[index],mag_shift);
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move16();
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}
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}
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}
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/* Get the first half of the windowed samples */
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out_ptr = out_samples;
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move16();
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test();
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if (dct_length==DCT_LENGTH)
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{
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win_new = rmlt_to_samples_window;
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move16();
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win_old = rmlt_to_samples_window + dct_length;
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move16();
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}
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else
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{
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win_new = max_rmlt_to_samples_window;
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move16();
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win_old = max_rmlt_to_samples_window + dct_length;
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move16();
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}
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old_ptr = old_samples;
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move16();
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new_ptr = new_samples + half_dct_size;
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move16();
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for (vals_left = half_dct_size; vals_left > 0; vals_left--)
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{
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sum = 0L;
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move32();
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sum = L_mac(sum,*win_new++, *--new_ptr);
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sum = L_mac(sum,*--win_old, *old_ptr++);
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*out_ptr++ = itu_round(L_shl_nocheck(sum,2));
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move16();
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}
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/* Get the second half of the windowed samples */
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for (vals_left = half_dct_size; vals_left > 0; vals_left--)
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{
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sum = 0L;
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move32();
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sum = L_mac(sum,*win_new++, *new_ptr++);
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sum = L_mac(sum,negate(*--win_old), *--old_ptr);
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*out_ptr++ = itu_round(L_shl_nocheck(sum,2));
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move16();
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}
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/* Save the second half of the new samples for */
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/* next time, when they will be the old samples. */
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/* pointer arithmetic */
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new_ptr = new_samples + half_dct_size;
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move16();
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old_ptr = old_samples;
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move16();
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for (vals_left = half_dct_size; vals_left > 0; vals_left--)
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{
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*old_ptr++ = *new_ptr++;
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move16();
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}
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}
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