mp3dec_subband_fp.c

这是在PCA下的基于IPP库示例代码例子,在网上下了IPP的库之后,设置相关参数就可以编译该代码.

/*//////////////////////////////////////////////////////////////////////////////
//
//                  INTEL CORPORATION PROPRIETARY INFORMATION
//     This software is supplied under the terms of a license agreement or
//     nondisclosure agreement with Intel Corporation and may not be copied
//     or disclosed except in accordance with the terms of that agreement.
//          Copyright(c) 2003-2005 Intel Corporation. All Rights Reserved.
//
*/

#include "mp3dec_own_fp.h"

/*
//  Functions in this file.
//
//  int mp3dec_SubBandSynth(MP3Dec* DC, int ch, int num)
*/

/******************************************************************************
//  Name:
//    mp3dec_SubBandSynth
//
//  Description:
//    Implementation of filterbank in the decoder that reconstructs a PCM audio
//    signal from subband samples.
//
//  Input Arguments:
//    DC - point to sDecoderContext structure
//    gr - number of granule
//    ch - number of channel
//
//  Output Arguments:
//    smpl_rw[ch] - reconstracted samples
//
//  Returns:
//    1 - all ok
//
******************************************************************************/
int mp3dec_SubBandSynth(MP3Dec *state, int ch, int num)
{
    int     i, odd, odd_idx, k, idx, even_idx, evn;

    float  *wnd_ptr_odd, *wnd_ptr_even;
    float  *flt_ptr_even, *flt_ptr_odd;

    float  *out = (*state->smpl_sb)[ch];
    float  *samples = (float *)(*state->smpl_rw)[ch];
    float  (*filter_bfr)[16][64] = state->filter_bfr;
    short   *m_even = state->m_even;
    short (*m_ptr)[2] = state->m_ptr;
    float *tmp_bfr = state->tmp_bfr;

    for (k = 0; k < num; k++) {
        m_even[ch] = (++m_even[ch] & 0x1);

        m_ptr[ch][m_even[ch]] = (m_ptr[ch][m_even[ch]] + 7) & 0x7;

        ippsDCTFwd_32f(samples, tmp_bfr, state->pDCTSpecFB, state->mdct_buffer);
        ippsMulC_32f_I(4, tmp_bfr, 32);
        tmp_bfr[0] *= 1.41421356f;

        idx = m_even[ch] * 8 + m_ptr[ch][m_even[ch]];

        for (i = 0; i < 16; i++) {
            filter_bfr[ch][idx][i] = tmp_bfr[i + 16];
        }
        filter_bfr[ch][idx][16] = 0;
        for (i = 17; i < 48; i++) {
            filter_bfr[ch][idx][i] = -tmp_bfr[48 - i];
        }
        for (i = 48; i < 64; i++) {
            filter_bfr[ch][idx][i] = -tmp_bfr[i - 48];
        }

        // calculate variables
        odd = ((m_even[ch] + 1) & 0x1);
        odd_idx = odd << 3;
        odd = (8 - m_ptr[ch][odd]) & 7;

        evn = (8 - m_ptr[ch][m_even[ch]]) & 7;
        even_idx = m_even[ch] << 3;

        wnd_ptr_even = mp3dec_Dcoef[0] + evn;
        wnd_ptr_odd = mp3dec_Dcoef[0] + odd + 15;

        flt_ptr_even = &filter_bfr[ch][even_idx][0];
        flt_ptr_odd = &filter_bfr[ch][odd_idx][32];

        // calculate samples
        for (i = 0; i < 32; i++) {
            out[i] =
                flt_ptr_even[0<<6] * wnd_ptr_even[0] +
                flt_ptr_even[1<<6] * wnd_ptr_even[1] +
                flt_ptr_even[2<<6] * wnd_ptr_even[2] +
                flt_ptr_even[3<<6] * wnd_ptr_even[3] +
                flt_ptr_even[4<<6] * wnd_ptr_even[4] +
                flt_ptr_even[5<<6] * wnd_ptr_even[5] +
                flt_ptr_even[6<<6] * wnd_ptr_even[6] +
                flt_ptr_even[7<<6] * wnd_ptr_even[7] +
                flt_ptr_odd[0<<6] * wnd_ptr_odd[0] +
                flt_ptr_odd[1<<6] * wnd_ptr_odd[1] +
                flt_ptr_odd[2<<6] * wnd_ptr_odd[2] +
                flt_ptr_odd[3<<6] * wnd_ptr_odd[3] +
                flt_ptr_odd[4<<6] * wnd_ptr_odd[4] +
                flt_ptr_odd[5<<6] * wnd_ptr_odd[5] +
                flt_ptr_odd[6<<6] * wnd_ptr_odd[6] +
                flt_ptr_odd[7<<6] * wnd_ptr_odd[7];

            flt_ptr_even ++;
            flt_ptr_odd ++;

            wnd_ptr_even += 30;
            wnd_ptr_odd += 30;
        }

        out += 32;
        samples += 32;
    }   // for

    return 1;
}