media/libstagefright/codecs/aacdec/sbr_downsample_lo_res.cpp

/* ------------------------------------------------------------------
 * Copyright (C) 1998-2009 PacketVideo
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied.
 * See the License for the specific language governing permissions
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/*

 Filename: sbr_downsample_lo_res.c

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 REVISION HISTORY


 Who:                                   Date: MM/DD/YYYY
 Description:

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 INPUT AND OUTPUT DEFINITIONS



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 FUNCTION DESCRIPTION


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 REQUIREMENTS


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 REFERENCES

SC 29 Software Copyright Licencing Disclaimer:

This software module was originally developed by
  Coding Technologies

and edited by
  -

in the course of development of the ISO/IEC 13818-7 and ISO/IEC 14496-3
standards for reference purposes and its performance may not have been
optimized. This software module is an implementation of one or more tools as
specified by the ISO/IEC 13818-7 and ISO/IEC 14496-3 standards.
ISO/IEC gives users free license to this software module or modifications
thereof for use in products claiming conformance to audiovisual and
image-coding related ITU Recommendations and/or ISO/IEC International
Standards. ISO/IEC gives users the same free license to this software module or
modifications thereof for research purposes and further ISO/IEC standardisation.
Those intending to use this software module in products are advised that its
use may infringe existing patents. ISO/IEC have no liability for use of this
software module or modifications thereof. Copyright is not released for
products that do not conform to audiovisual and image-coding related ITU
Recommendations and/or ISO/IEC International Standards.
The original developer retains full right to modify and use the code for its
own purpose, assign or donate the code to a third party and to inhibit third
parties from using the code for products that do not conform to audiovisual and
image-coding related ITU Recommendations and/or ISO/IEC International Standards.
This copyright notice must be included in all copies or derivative works.
Copyright (c) ISO/IEC 2002.

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 PSEUDO-CODE

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*/


/*----------------------------------------------------------------------------
; INCLUDES
----------------------------------------------------------------------------*/

#ifdef AAC_PLUS


#include    "sbr_downsample_lo_res.h"
#include    "sbr_constants.h"

/*----------------------------------------------------------------------------
; MACROS
; Define module specific macros here
----------------------------------------------------------------------------*/


/*----------------------------------------------------------------------------
; DEFINES
; Include all pre-processor statements here. Include conditional
; compile variables also.
----------------------------------------------------------------------------*/

/*----------------------------------------------------------------------------
; LOCAL FUNCTION DEFINITIONS
; Function Prototype declaration
----------------------------------------------------------------------------*/

/*----------------------------------------------------------------------------
; LOCAL STORE/BUFFER/POINTER DEFINITIONS
; Variable declaration - defined here and used outside this module
----------------------------------------------------------------------------*/

/*----------------------------------------------------------------------------
; EXTERNAL FUNCTION REFERENCES
; Declare functions defined elsewhere and referenced in this module
----------------------------------------------------------------------------*/

/*----------------------------------------------------------------------------
; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES
; Declare variables used in this module but defined elsewhere
----------------------------------------------------------------------------*/

/*----------------------------------------------------------------------------
; FUNCTION CODE
----------------------------------------------------------------------------*/

void  sbr_downsample_lo_res(Int32 v_result[],
                            Int32 num_result,
                            Int   freqBandTableRef[],
                            Int32 num_Ref)
{
    Int32 step;
    Int32 i, j;
    Int32 org_length;
    Int32 result_length;
    Int32 v_index[MAX_FREQ_COEFFS/2];

    /* init */
    org_length = num_Ref;
    result_length = num_result;

    v_index[0] = 0; /* Always use left border */
    i = 0;
    while (org_length > 0)  /* Create downsample vector */
    {
        i++;
        step = org_length / result_length; /* floor; */
        org_length = org_length - step;
        result_length--;
        v_index[i] = v_index[i-1] + step;
    }

    for (j = 0; j <= i; j++)   /* Use downsample vector to index LoResolution vector. */
    {
        v_result[j] = freqBandTableRef[ v_index[j]];
    }

}  /* End downSampleLoRes */

#endif