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annotate libtwamr/d_gain_c.h @ 477:4c9222d95647

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libtwamr encoder: always emit frame->mode = mode; In the original implementation of amr_encode_frame(), the 'mode' member of the output struct was set to 0xFF if the output frame type is TX_NO_DATA. This design was made to mimic the mode field (16-bit word) being set to 0xFFFF (or -1) in 3GPP test sequence format - but nothing actually depends on this struct member being set in any way, and amr_frame_to_tseq() generates the needed 0xFFFF on its own, based on frame->type being equal to TX_NO_DATA. It is simpler and more efficient to always set frame->mode to the actual encoding mode in amr_encode_frame(), and this new behavior has already been documented in doc/AMR-library-API description in anticipation of the present change.
author Mychaela Falconia <falcon@freecalypso.org>
date Sat, 18 May 2024 22:30:42 +0000
parents a723d9f9f697
children
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a723d9f9f697 libtwamr: integrate d_gain_c.c
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1 /*
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2 ********************************************************************************
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3 *
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4 * GSM AMR-NB speech codec R98 Version 7.6.0 December 12, 2001
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5 * R99 Version 3.3.0
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6 * REL-4 Version 4.1.0
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7 *
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8 ********************************************************************************
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9 *
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10 * File : d_gain_c.h
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11 * Purpose : Decode the fixed codebook gain using the received index.
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12 *
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13 ********************************************************************************
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14 */
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15 #ifndef d_gain_c_h
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16 #define d_gain_c_h "$Id $"
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17
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18 /*
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19 ********************************************************************************
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20 * INCLUDE FILES
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21 ********************************************************************************
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22 */
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23 #include "tw_amr.h"
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24 #include "typedef.h"
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25 #include "gc_pred.h"
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26
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27 /*
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28 ********************************************************************************
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29 * DECLARATION OF PROTOTYPES
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30 ********************************************************************************
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31 */
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32 /*
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33 **************************************************************************
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34 *
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35 * Function : d_gain_code
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36 * Purpose : Decode the fixed codebook gain using the received index.
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37 * Description : The received index gives the gain correction factor
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38 * gamma. The quantized gain is given by g_q = g0 * gamma
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39 * where g0 is the predicted gain. To find g0, 4th order
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40 * MA prediction is applied to the mean-removed innovation
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41 * energy in dB.
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42 * Returns : void
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43 *
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44 **************************************************************************
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45 */
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46 void d_gain_code (
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47 gc_predState *pred_state, /* i/o : MA predictor state */
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48 enum Mode mode, /* i : AMR mode */
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49 Word16 index, /* i : received quantization index */
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50 Word16 code[], /* i : innovation codevector */
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51 Word16 *gain_code /* o : decoded innovation gain */
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52 );
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53
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54 #endif