Merge branch '1963_basop_portFltMR-1568-1471-1690' into hrtf_improvements_basop (c1a86f36) · Commits · SA4 / Audio / IVAS BASOP

lib_util/ambi_convert.c

0 → 100644

+504 −0

Original line number	Diff line number	Diff line
		/******************************************************************************************************

		(C) 2022-2025 IVAS codec Public Collaboration with portions copyright Dolby International AB, Ericsson AB,
		Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Huawei Technologies Co. LTD.,
		Koninklijke Philips N.V., Nippon Telegraph and Telephone Corporation, Nokia Technologies Oy, Orange,
		Panasonic Holdings Corporation, Qualcomm Technologies, Inc., VoiceAge Corporation, and other
		contributors to this repository. All Rights Reserved.

		This software is protected by copyright law and by international treaties.
		The IVAS codec Public Collaboration consisting of Dolby International AB, Ericsson AB,
		Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Huawei Technologies Co. LTD.,
		Koninklijke Philips N.V., Nippon Telegraph and Telephone Corporation, Nokia Technologies Oy, Orange,
		Panasonic Holdings Corporation, Qualcomm Technologies, Inc., VoiceAge Corporation, and other
		contributors to this repository retain full ownership rights in their respective contributions in
		the software. This notice grants no license of any kind, including but not limited to patent
		license, nor is any license granted by implication, estoppel or otherwise.

		Contributors are required to enter into the IVAS codec Public Collaboration agreement before making
		contributions.

		This software is provided "AS IS", without any express or implied warranties. The software is in the
		development stage. It is intended exclusively for experts who have experience with such software and
		solely for the purpose of inspection. All implied warranties of non-infringement, merchantability
		and fitness for a particular purpose are hereby disclaimed and excluded.

		Any dispute, controversy or claim arising under or in relation to providing this software shall be
		submitted to and settled by the final, binding jurisdiction of the courts of Munich, Germany in
		accordance with the laws of the Federal Republic of Germany excluding its conflict of law rules and
		the United Nations Convention on Contracts on the International Sales of Goods.

		*******************************************************************************************************/

		#include <assert.h>
		#include <stdio.h>
		#include "wmc_auto.h"
		#include "ambi_convert.h"

		#define ONE_1_Q29 536870912l /* 1.0f */
		#define ONE_OVER_2_Q29 268435456l /* 1.0f/2.0f */

		#define SQRT_2_Q29 759250112l /* sqrtf(2.0f) */
		#define SQRT_3_Q29 929887680l /* sqrtf(3.0f) */
		#define SQRT_5_Q29 1200479872l /* sqrtf(5.0f) */
		#define SQRT_7_Q29 1420426880l /* sqrtf(7.0f) */

		#define INV_SQRT_2_Q29 379625024l /* 1.0f/sqrtf(2.0f) */
		#define INV_SQRT_3_Q29 309962528l /* 1.0f/sqrtf(3.0f) */
		#define INV_SQRT_5_Q29 240095920l /* 1.0f/sqrtf(5.0f) */
		#define INV_SQRT_7_Q29 202918096l /* 1.0f/sqrtf(7.0f) */

		#define TWO_OVER_SQRT_3_Q29 619925120l /* 2.0f/sqrtf(3.0f) */
		#define THREE_OVER_SQRT_5_Q29 720287936l /* 3.0f/sqrtf(5.0f) */
		#define SQRT_8_OVER_5_Q29 679093952l /* sqrtf(8.0f/5.0f) */
		#define SQRT_45_OVER_32_Q29 636650560l /* sqrtf(45.0f/32.0f) */

		#define INV_TWO_OVER_SQRT_3_Q29 464943840l /* 1.0f/TWO_OVER_SQRT_3_Q29 */
		#define INV_THREE_OVER_SQRT_5_Q29 400159968l /* 1.0f/THREE_OVER_SQRT_5_Q29 */
		#define INV_SQRT_8_OVER_5_Q29 424433728l /* 1.0f/INV_SQRT_8_OVER_5_Q29 */
		#define INV_SQRT_45_OVER_32_Q29 452729280l /* 1.0f/SQRT_45_OVER_32_Q29 */


		/* --------------------------------
		normalization conversion tables
		-------------------------------- */

		static const Word32 SN3D_N3D[AMBI_MAX_CHANNELS] = { ONE_1_Q29,
		SQRT_3_Q29, SQRT_3_Q29, SQRT_3_Q29,
		SQRT_5_Q29, SQRT_5_Q29, SQRT_5_Q29, SQRT_5_Q29, SQRT_5_Q29,
		SQRT_7_Q29, SQRT_7_Q29, SQRT_7_Q29, SQRT_7_Q29, SQRT_7_Q29, SQRT_7_Q29, SQRT_7_Q29 };

		static const Word32 N3D_SN3D[AMBI_MAX_CHANNELS] = { ONE_1_Q29,
		INV_SQRT_3_Q29, INV_SQRT_3_Q29, INV_SQRT_3_Q29,
		INV_SQRT_5_Q29, INV_SQRT_5_Q29, INV_SQRT_5_Q29, INV_SQRT_5_Q29, INV_SQRT_5_Q29,
		INV_SQRT_7_Q29, INV_SQRT_7_Q29, INV_SQRT_7_Q29, INV_SQRT_7_Q29, INV_SQRT_7_Q29, INV_SQRT_7_Q29, INV_SQRT_7_Q29 };


		static const Word32 SN3D_MAXN[AMBI_MAX_CHANNELS] = { ONE_1_Q29,
		ONE_1_Q29, ONE_1_Q29, ONE_1_Q29,
		TWO_OVER_SQRT_3_Q29, TWO_OVER_SQRT_3_Q29, ONE_1_Q29, TWO_OVER_SQRT_3_Q29, TWO_OVER_SQRT_3_Q29,
		SQRT_8_OVER_5_Q29, THREE_OVER_SQRT_5_Q29, SQRT_45_OVER_32_Q29, ONE_1_Q29, SQRT_45_OVER_32_Q29, THREE_OVER_SQRT_5_Q29, SQRT_8_OVER_5_Q29 };

		static const Word32 MAXN_SN3D[AMBI_MAX_CHANNELS] = { ONE_1_Q29,
		ONE_1_Q29, ONE_1_Q29, ONE_1_Q29,
		INV_TWO_OVER_SQRT_3_Q29, INV_TWO_OVER_SQRT_3_Q29, ONE_1_Q29, INV_TWO_OVER_SQRT_3_Q29, INV_TWO_OVER_SQRT_3_Q29,
		INV_SQRT_8_OVER_5_Q29, INV_THREE_OVER_SQRT_5_Q29, INV_SQRT_45_OVER_32_Q29, ONE_1_Q29, INV_SQRT_45_OVER_32_Q29, INV_THREE_OVER_SQRT_5_Q29, INV_SQRT_8_OVER_5_Q29 };

		static const Word32 SN3D_FM[AMBI_MAX_CHANNELS] = { INV_SQRT_2_Q29,
		ONE_1_Q29, ONE_1_Q29, ONE_1_Q29,
		TWO_OVER_SQRT_3_Q29, TWO_OVER_SQRT_3_Q29, ONE_1_Q29, TWO_OVER_SQRT_3_Q29, TWO_OVER_SQRT_3_Q29,
		SQRT_8_OVER_5_Q29, THREE_OVER_SQRT_5_Q29, SQRT_45_OVER_32_Q29, ONE_1_Q29, SQRT_45_OVER_32_Q29, THREE_OVER_SQRT_5_Q29, SQRT_8_OVER_5_Q29 };

		static const Word32 FM_SN3D[AMBI_MAX_CHANNELS] = { SQRT_2_Q29,
		ONE_1_Q29, ONE_1_Q29, ONE_1_Q29,
		INV_TWO_OVER_SQRT_3_Q29, INV_TWO_OVER_SQRT_3_Q29, ONE_1_Q29, INV_TWO_OVER_SQRT_3_Q29, INV_TWO_OVER_SQRT_3_Q29,
		INV_SQRT_8_OVER_5_Q29, INV_THREE_OVER_SQRT_5_Q29, INV_SQRT_45_OVER_32_Q29, ONE_1_Q29, INV_SQRT_45_OVER_32_Q29, INV_THREE_OVER_SQRT_5_Q29, INV_SQRT_8_OVER_5_Q29 };

		/* ----------------------------
		channel re-ordering tables
		---------------------------- */

		static const int16_t REORDER_FM_ACN[AMBI_MAX_CHANNELS] = { 0,
		2, 3, 1,
		8, 6, 4, 5, 7,
		15, 13, 11, 9, 10, 12, 14 };

		static const int16_t REORDER_SID_ACN[AMBI_MAX_CHANNELS] = { 0,
		2, 3, 1,
		5, 7, 8, 6, 4,
		10, 12, 14, 15, 13, 11, 9 };

		static const int16_t REORDER_ACN_FM[AMBI_MAX_CHANNELS] = { 0,
		3, 1, 2,
		6, 7, 5, 8, 4,
		12, 13, 11, 14, 10, 15, 9 };

		static const int16_t REORDER_ACN_SID[AMBI_MAX_CHANNELS] = { 0,
		3, 1, 2,
		8, 4, 7, 5, 6,
		15, 9, 14, 10, 13, 11, 12 };

		/* ----------------------------------
		API functions for the conversion
		---------------------------------- */

		/-------------------------------------------------------------------------
		* convert_ambi_format()
		*
		* Convert signal between ACN-SN3D and other common ambisonics conventions
		--------------------------------------------------------------------------*/

		AMBI_CONVERT_ERROR convert_ambi_format(
		Word16 in[], / i: input ambisonics channels, Q0 */
		Word16 out[], / o: output ambisonics channels, Q0 */
		int16_t order, /* i: ambisonics order */
		AMBI_FMT in_format, /* i: input ambisonics format */
		AMBI_FMT out_format /* i: output ambisonics format */
		)
		{

		Word16 tmp[AMBI_MAX_CHANNELS * L_FRAME48k];
		Word16 *p_tmp[AMBI_MAX_CHANNELS];
		AMBI_CONVERT_ERROR err = AMBI_CONVERT_OK;

		AMBI_CHANNEL_ORDER ch_ord_in = AMBI_CHANNEL_ORDER_ACN;
		AMBI_CHANNEL_ORDER ch_ord_out = AMBI_CHANNEL_ORDER_ACN;

		AMBI_CHANNEL_NORM ch_norm_in = AMBI_NORM_SN3D;
		AMBI_CHANNEL_NORM ch_norm_out = AMBI_NORM_SN3D;

		Word16 i, j;

		assert( order <= 3 );

		if ( in_format != AMBI_FMT_ACN_SN3D && out_format != AMBI_FMT_ACN_SN3D )
		{
		assert( 0 && "Conversion only supported to and from ACN-SN3D" );
		}
		i = 0;
		move16();
		FOR( j = 0; j < AMBI_MAX_CHANNELS; j++ )
		{
		p_tmp[j] = &tmp[i];
		move32();
		i = add( i, L_FRAME48k );
		}

		SWITCH( in_format )
		{
		case AMBI_FMT_ACN_SN3D:
		ch_ord_in = AMBI_CHANNEL_ORDER_ACN;
		ch_norm_in = AMBI_NORM_SN3D;
		move16();
		move16();
		break;
		case AMBI_FMT_ACN_N3D:
		ch_ord_in = AMBI_CHANNEL_ORDER_ACN;
		ch_norm_in = AMBI_NORM_N3D;
		move16();
		move16();
		break;
		case AMBI_FMT_FM_MAXN:
		ch_ord_in = AMBI_CHANNEL_ORDER_FM;
		ch_norm_in = AMBI_NORM_MAXN;
		move16();
		move16();
		break;
		case AMBI_FMT_FM_FM:
		ch_ord_in = AMBI_CHANNEL_ORDER_FM;
		ch_norm_in = AMBI_NORM_FM;
		move16();
		move16();
		break;
		case AMBI_FMT_SID_SN3D:
		ch_ord_in = AMBI_CHANNEL_ORDER_SID;
		ch_norm_in = AMBI_NORM_SN3D;
		move16();
		move16();
		break;
		case AMBI_FMT_SID_N3D:
		ch_ord_in = AMBI_CHANNEL_ORDER_SID;
		ch_norm_in = AMBI_NORM_N3D;
		move16();
		move16();
		break;
		default:
		return AMBI_CONVERT_UNSUPPORTED_CONVERSION;
		}

		SWITCH( out_format )
		{
		case AMBI_FMT_ACN_SN3D:
		ch_ord_out = AMBI_CHANNEL_ORDER_ACN;
		ch_norm_out = AMBI_NORM_SN3D;
		move16();
		move16();
		break;
		case AMBI_FMT_ACN_N3D:
		ch_ord_out = AMBI_CHANNEL_ORDER_ACN;
		ch_norm_out = AMBI_NORM_N3D;
		move16();
		move16();
		break;
		case AMBI_FMT_FM_MAXN:
		ch_ord_out = AMBI_CHANNEL_ORDER_FM;
		ch_norm_out = AMBI_NORM_MAXN;
		move16();
		move16();
		break;
		case AMBI_FMT_FM_FM:
		ch_ord_out = AMBI_CHANNEL_ORDER_FM;
		ch_norm_out = AMBI_NORM_FM;
		move16();
		move16();
		break;
		case AMBI_FMT_SID_SN3D:
		ch_ord_out = AMBI_CHANNEL_ORDER_SID;
		ch_norm_out = AMBI_NORM_SN3D;
		move16();
		move16();
		break;
		case AMBI_FMT_SID_N3D:
		ch_ord_out = AMBI_CHANNEL_ORDER_SID;
		ch_norm_out = AMBI_NORM_N3D;
		move16();
		move16();
		break;
		default:
		return AMBI_CONVERT_UNSUPPORTED_CONVERSION;
		}

		IF( in_format == AMBI_FMT_ACN_SN3D && ch_norm_in != ch_norm_out )
		{
		IF( ch_ord_in != ch_ord_out )
		{
		IF( ( err = renormalize_channels( in, p_tmp, order, ch_norm_in, ch_norm_out ) ) != AMBI_CONVERT_OK )
		{
		return err;
		}
		IF( ( err = reorder_channels( p_tmp, out, order, ch_ord_in, ch_ord_out ) ) != AMBI_CONVERT_OK )
		{
		return err;
		}
		}
		ELSE
		{
		IF( ( err = renormalize_channels( in, out, order, ch_norm_in, ch_norm_out ) ) != AMBI_CONVERT_OK )
		{
		return err;
		}
		}
		}
		ELSE IF( in_format == AMBI_FMT_ACN_SN3D && ch_ord_in != ch_ord_out )
		{
		IF( ( err = reorder_channels( in, out, order, ch_ord_in, ch_ord_out ) ) != AMBI_CONVERT_OK )
		{
		return err;
		}
		}
		ELSE IF( out_format == AMBI_FMT_ACN_SN3D && ch_norm_in != ch_norm_out )
		{
		IF( ch_ord_in != ch_ord_out )
		{
		IF( ( err = reorder_channels( in, p_tmp, order, ch_ord_in, ch_ord_out ) ) != AMBI_CONVERT_OK )
		{
		return err;
		}
		IF( ( err = renormalize_channels( p_tmp, out, order, ch_norm_in, ch_norm_out ) ) != AMBI_CONVERT_OK )
		{
		return err;
		}
		}
		ELSE
		{
		IF( ( err = renormalize_channels( in, out, order, ch_norm_in, ch_norm_out ) ) != AMBI_CONVERT_OK )
		{
		return err;
		}
		}
		}
		ELSE IF( out_format == AMBI_FMT_ACN_SN3D && ch_ord_in != ch_ord_out )
		{
		IF( ( err = reorder_channels( in, out, order, ch_ord_in, ch_ord_out ) ) != AMBI_CONVERT_OK )
		{
		return err;
		}
		}
		ELSE IF( out_format == AMBI_FMT_ACN_SN3D && in_format == AMBI_FMT_ACN_SN3D )
		{
		int16_t i_chan = 0;
		int16_t n_chan = i_mult2( add( order, 1 ), add( order, 1 ) );

		FOR( i_chan = 0; i_chan < n_chan; i_chan++ )
		{
		int16_t i = 0;
		move16();
		FOR( i = 0; i < L_FRAME48k; i++ )
		{
		out[i_chan][i] = in[i_chan][i];
		move16();
		}
		}
		}
		ELSE
		{
		assert( 0 && "This should never happen!" );
		}

		return AMBI_CONVERT_OK;
		}

		/-------------------------------------------------------------------------
		* renormalize_channels()
		*
		* Rescale audio channels according to the selected ambisonics convention
		--------------------------------------------------------------------------*/

		AMBI_CONVERT_ERROR renormalize_channels(
		Word16 in[], / i: input ambisonics channels, Q0 */
		Word16 out[], / o: output ambisonics channels, Q0 */
		int16_t order, /* i: ambisonics order */
		AMBI_CHANNEL_NORM in_format, /* i: input ambisonics format */
		AMBI_CHANNEL_NORM out_format /* i: output ambisonics format */
		)
		{
		int16_t n_chan = i_mult2( add( order, 1 ), add( order, 1 ) );
		int16_t i_chan, i;
		const Word32 *conversion_table = 0;
		Word32 minval = 0;
		Word32 maxval = 0;
		move32();
		move32();
		move32();


		/* conversion factors are applied on the channels assuming that they are still/already in ACN order */
		IF( in_format == AMBI_NORM_SN3D )
		{
		IF( out_format == AMBI_NORM_N3D )
		{
		conversion_table = SN3D_N3D;
		move32();
		}
		ELSE IF( out_format == AMBI_NORM_MAXN )
		{
		conversion_table = SN3D_MAXN;
		move32();
		}
		ELSE IF( out_format == AMBI_NORM_FM )
		{
		conversion_table = SN3D_FM;
		move32();
		}
		ELSE
		{
		return AMBI_CONVERT_UNSUPPORTED_CONVERSION;
		}
		}
		ELSE IF( out_format == AMBI_NORM_SN3D )
		{
		IF( in_format == AMBI_NORM_N3D )
		{
		conversion_table = N3D_SN3D;
		move32();
		}
		ELSE IF( in_format == AMBI_NORM_MAXN )
		{
		conversion_table = MAXN_SN3D;
		move32();
		}
		ELSE IF( in_format == AMBI_NORM_FM )
		{
		conversion_table = FM_SN3D;
		move32();
		}
		ELSE
		{
		return AMBI_CONVERT_UNSUPPORTED_CONVERSION;
		}
		}
		ELSE
		{
		return AMBI_CONVERT_UNSUPPORTED_CONVERSION;
		}


		FOR( i_chan = 0; i_chan < n_chan; i_chan++ )
		{
		Word32 conversion_factor = conversion_table[i_chan];
		Word32 outval;
		move32();
		FOR( i = 0; i < L_FRAME48k; i++ )
		{
		Word64 tmp;
		tmp = W_mult0_32_32( (Word32) in[i_chan][i], conversion_factor );
		/* tmp = W_add( tmp, ONE_OVER_2_Q29); / / rounding up */
		outval = W_extract_l( W_shr( tmp, Q29 ) );
		minval = L_min( minval, outval );
		maxval = L_min( maxval, outval );
		out[i_chan][i] = extract_l( outval );
		}
		}
		IF( ( minval < MIN16B ) \|\| ( maxval > MAX16B ) )
		{
		return AMBI_CONVERT_CLIPPING_DETECTED;
		}
		return AMBI_CONVERT_OK;
		}

		/-------------------------------------------------------------------------
		* reorder_channels()
		*
		* Reorder channels according to the selected ambisonics convention
		--------------------------------------------------------------------------*/

		AMBI_CONVERT_ERROR reorder_channels(
		Word16 in[], / i: input ambisonics channels, Q0 */
		Word16 out[], / o: output ambisonics channels, Q0 */
		int16_t order, /* i: ambisonics order */
		AMBI_CHANNEL_ORDER in_format, /* i: input ambisonics format */
		AMBI_CHANNEL_ORDER out_format /* i: output ambisonics format */
		)
		{
		int16_t n_chan = i_mult2( add( order, 1 ), add( order, 1 ) );
		int16_t i_chan, i;
		Word16 tmp[AMBI_MAX_CHANNELS];
		const int16_t *idx_table = 0;

		IF( in_format == AMBI_CHANNEL_ORDER_ACN )
		{
		IF( out_format == AMBI_CHANNEL_ORDER_FM )
		{
		idx_table = REORDER_ACN_FM;
		move16();
		}
		ELSE IF( out_format == AMBI_CHANNEL_ORDER_SID )
		{
		idx_table = REORDER_ACN_SID;
		move16();
		}
		ELSE
		{
		return AMBI_CONVERT_UNSUPPORTED_CONVERSION;
		}
		}
		ELSE IF( out_format == AMBI_CHANNEL_ORDER_ACN )
		{
		IF( in_format == AMBI_CHANNEL_ORDER_FM )
		{
		idx_table = REORDER_FM_ACN;
		move16();
		}
		ELSE IF( in_format == AMBI_CHANNEL_ORDER_SID )
		{
		idx_table = REORDER_SID_ACN;
		move16();
		}
		ELSE
		{
		return AMBI_CONVERT_UNSUPPORTED_CONVERSION;
		}
		}
		ELSE
		{
		return AMBI_CONVERT_UNSUPPORTED_CONVERSION;
		}

		FOR( i = 0; i < L_FRAME48k; i++ )
		{
		FOR( i_chan = 0; i_chan < n_chan; i_chan++ )
		{
		int16_t idx = idx_table[i_chan];
		move16();
		tmp[i_chan] = in[idx][i];
		move16();
		}
		FOR( i_chan = 0; i_chan < n_chan; i_chan++ )
		{
		out[i_chan][i] = tmp[i_chan];
		move16();
		}
		}

		return AMBI_CONVERT_OK;
		}

lib_util/ambi_convert.h

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+103 −0

Original line number	Diff line number	Diff line
		/******************************************************************************************************

		(C) 2022-2025 IVAS codec Public Collaboration with portions copyright Dolby International AB, Ericsson AB,
		Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Huawei Technologies Co. LTD.,
		Koninklijke Philips N.V., Nippon Telegraph and Telephone Corporation, Nokia Technologies Oy, Orange,
		Panasonic Holdings Corporation, Qualcomm Technologies, Inc., VoiceAge Corporation, and other
		contributors to this repository. All Rights Reserved.

		This software is protected by copyright law and by international treaties.
		The IVAS codec Public Collaboration consisting of Dolby International AB, Ericsson AB,
		Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Huawei Technologies Co. LTD.,
		Koninklijke Philips N.V., Nippon Telegraph and Telephone Corporation, Nokia Technologies Oy, Orange,
		Panasonic Holdings Corporation, Qualcomm Technologies, Inc., VoiceAge Corporation, and other
		contributors to this repository retain full ownership rights in their respective contributions in
		the software. This notice grants no license of any kind, including but not limited to patent
		license, nor is any license granted by implication, estoppel or otherwise.

		Contributors are required to enter into the IVAS codec Public Collaboration agreement before making
		contributions.

		This software is provided "AS IS", without any express or implied warranties. The software is in the
		development stage. It is intended exclusively for experts who have experience with such software and
		solely for the purpose of inspection. All implied warranties of non-infringement, merchantability
		and fitness for a particular purpose are hereby disclaimed and excluded.

		Any dispute, controversy or claim arising under or in relation to providing this software shall be
		submitted to and settled by the final, binding jurisdiction of the courts of Munich, Germany in
		accordance with the laws of the Federal Republic of Germany excluding its conflict of law rules and
		the United Nations Convention on Contracts on the International Sales of Goods.

		*******************************************************************************************************/

		#ifndef AMBI_CONVERT_H
		#define AMBI_CONVERT_H

		#include <stdint.h>
		#include "options.h"
		#include "prot_fx.h"
		#include "ivas_cnst.h"
		#include <math.h>
		#include "wmc_auto.h"
		#include "ivas_prot_fx.h"


		#define L_FRAME48k 960
		#define AMBI_MAX_CHANNELS 16

		typedef enum
		{
		AMBI_FMT_ACN_SN3D = 0,
		AMBI_FMT_ACN_N3D,
		AMBI_FMT_FM_MAXN,
		AMBI_FMT_FM_FM,
		AMBI_FMT_SID_SN3D,
		AMBI_FMT_SID_N3D
		} AMBI_FMT;

		typedef enum
		{
		AMBI_NORM_SN3D = 0,
		AMBI_NORM_N3D,
		AMBI_NORM_MAXN,
		AMBI_NORM_FM
		} AMBI_CHANNEL_NORM;

		typedef enum
		{
		AMBI_CHANNEL_ORDER_ACN = 0,
		AMBI_CHANNEL_ORDER_FM,
		AMBI_CHANNEL_ORDER_SID
		} AMBI_CHANNEL_ORDER;

		typedef enum
		{
		AMBI_CONVERT_OK = 0,
		AMBI_CONVERT_UNSUPPORTED_CONVERSION,
		AMBI_CONVERT_CLIPPING_DETECTED
		} AMBI_CONVERT_ERROR;

		AMBI_CONVERT_ERROR convert_ambi_format(
		Word16 in[], / i: input ambisonics channels, Q0 */
		Word16 out[], / o: output ambisonics channels, Q0 */
		int16_t order, /* i: ambisonics order */
		AMBI_FMT in_format, /* i: input ambisonics format */
		AMBI_FMT out_format /* i: output ambisonics format */
		);

		AMBI_CONVERT_ERROR renormalize_channels(
		Word16 in[], / i: input ambisonics channels, Q0 */
		Word16 out[], / o: output ambisonics channels, Q0 */
		int16_t order, /* i: ambisonics order */
		AMBI_CHANNEL_NORM in_format, /* i: input ambisonics format */
		AMBI_CHANNEL_NORM out_format /* i: output ambisonics format */
		);

		AMBI_CONVERT_ERROR reorder_channels(
		Word16 in[], / i: input ambisonics channels, Q0 */
		Word16 out[], / o: output ambisonics channels, Q0 */
		int16_t order, /* i: ambisonics order */
		AMBI_CHANNEL_ORDER in_format, /* i: input ambisonics format */
		AMBI_CHANNEL_ORDER out_format /* i: output ambisonics format */
		);
		#endif