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annotate libtwamr/preemph.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 3618b5cf25a6
children
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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 : preemph.h
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11 * Purpose : Preemphasis filtering
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12 * Description : Filtering through 1 - g z^-1
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13 *
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14 ********************************************************************************
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15 */
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16 #ifndef preemph_h
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17 #define preemph_h "$Id $"
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18
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19 /*
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20 ********************************************************************************
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21 * INCLUDE FILES
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22 ********************************************************************************
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23 */
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24 #include "typedef.h"
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25
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26 /*
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27 ********************************************************************************
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28 * DEFINITION OF DATA TYPES
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29 ********************************************************************************
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30 */
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31 typedef struct {
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32 Word16 mem_pre; /* filter state */
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33 } preemphasisState;
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34
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35 /*
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36 ********************************************************************************
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37 * DECLARATION OF PROTOTYPES
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38 ********************************************************************************
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39 */
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40
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41 void preemphasis_reset (preemphasisState *st);
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42 /* reset of preemphasis filter (i.e. set state memory to zero)
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43 returns 0 on success
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44 */
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45
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46 int preemphasis (
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47 preemphasisState *st, /* (i/o): preemphasis filter state */
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48 Word16 *signal, /* (i/o): input signal overwritten by the output */
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49 Word16 g, /* (i) : preemphasis coefficient */
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50 Word16 L /* (i) : size of filtering */
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51 );
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52
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53 #endif