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view amrconv/if1_unpack.c @ 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 934cf92a1c45
children
line wrap: on
line source

/*
 * In this module we implement our function for unpacking bits from AMR IF1
 * and reshuffling them into the codec's natural bit order.
 */

#include <stdint.h>
#include "amr_defs.h"

extern const uint8_t amr_475_bit_order[95];
extern const uint8_t amr_515_bit_order[103];
extern const uint8_t amr_59_bit_order[118];
extern const uint8_t amr_67_bit_order[134];
extern const uint8_t amr_74_bit_order[148];
extern const uint8_t amr_795_bit_order[159];
extern const uint8_t amr_102_bit_order[204];
extern const uint8_t amr_122_bit_order[244];

static void
unpack_bits(if1_bytes, codec_bits, nbits, table)
	uint8_t *if1_bytes, *codec_bits;
	unsigned nbits;
	const uint8_t *table;
{
	unsigned n, nb;

	for (n = 0; n < nbits; n++) {
		if (table)
			nb = table[n];
		else
			nb = n;
		codec_bits[nb] = msb_get_bit(if1_bytes, n);
	}
}

amr_if1_unpack(if1_bytes, codec_bits, mode)
	uint8_t *if1_bytes, *codec_bits;
	unsigned mode;
{
	switch (mode) {
	case MR475:
		unpack_bits(if1_bytes, codec_bits, AMR_NBITS_475,
				amr_475_bit_order);
		return(0);
	case MR515:
		unpack_bits(if1_bytes, codec_bits, AMR_NBITS_515,
				amr_515_bit_order);
		return(0);
	case MR59:
		unpack_bits(if1_bytes, codec_bits, AMR_NBITS_59,
				amr_59_bit_order);
		return(0);
	case MR67:
		unpack_bits(if1_bytes, codec_bits, AMR_NBITS_67,
				amr_67_bit_order);
		return(0);
	case MR74:
		unpack_bits(if1_bytes, codec_bits, AMR_NBITS_74,
				amr_74_bit_order);
		return(0);
	case MR795:
		unpack_bits(if1_bytes, codec_bits, AMR_NBITS_795,
				amr_795_bit_order);
		return(0);
	case MR102:
		unpack_bits(if1_bytes, codec_bits, AMR_NBITS_102,
				amr_102_bit_order);
		return(0);
	case MR122:            
		unpack_bits(if1_bytes, codec_bits, AMR_NBITS_122,
				amr_122_bit_order);
		return(0);
	case MRDTX:
		unpack_bits(if1_bytes, codec_bits, AMR_NBITS_SID,
				(const uint8_t *) 0);
		return(0);
	default:
		return(-1);
	}
}