mp3dec_layer2_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"

static float C_quant[] = {
    1.33333333333f,
    1.60000000000f,
    1.14285714286f,
    1.77777777777f,
    1.06666666666f,
    1.03225806452f,
    1.01587301587f,
    1.00787401575f,
    1.00392156863f,
    1.00195694716f,
    1.00097751711f,
    1.00048851979f,
    1.00024420024f,
    1.00012208522f,
    1.00006103888f,
    1.00003051851f,
    1.00001525902f
};

static float D_quant[] = {
    16384, 16384, 8192, 16384, 4096, 2048, 1024, 512,
    256, 128, 64, 32, 16, 8, 4, 2, 1,
};

float mp3dec_scale_values[64] = {
    2.00000000000000f, 1.58740105196820f, 1.25992104989487f,
    1.00000000000000f, 0.79370052598410f, 0.62996052494744f, 0.50000000000000f,
    0.39685026299205f, 0.31498026247372f, 0.25000000000000f, 0.19842513149602f,
    0.15749013123686f, 0.12500000000000f, 0.09921256574801f, 0.07874506561843f,
    0.06250000000000f, 0.04960628287401f, 0.03937253280921f, 0.03125000000000f,
    0.02480314143700f, 0.01968626640461f, 0.01562500000000f, 0.01240157071850f,
    0.00984313320230f, 0.00781250000000f, 0.00620078535925f, 0.00492156660115f,
    0.00390625000000f, 0.00310039267963f, 0.00246078330058f, 0.00195312500000f,
    0.00155019633981f, 0.00123039165029f, 0.00097656250000f, 0.00077509816991f,
    0.00061519582514f, 0.00048828125000f, 0.00038754908495f, 0.00030759791257f,
    0.00024414062500f, 0.00019377454248f, 0.00015379895629f, 0.00012207031250f,
    0.00009688727124f, 0.00007689947814f, 0.00006103515625f, 0.00004844363562f,
    0.00003844973907f, 0.00003051757813f, 0.00002422181781f, 0.00001922486954f,
    0.00001525878906f, 0.00001211090890f, 0.00000961243477f, 0.00000762939453f,
    0.00000605545445f, 0.00000480621738f, 0.00000381469727f, 0.00000302772723f,
    0.00000240310869f, 0.00000190734863f, 0.00000151386361f, 0.00000120155435f,
    1E-20f
};

int mp3dec_decode_data_LayerII(MP3Dec *state)
{
    int i, ch, sb;
    float *pSampl[2];
    float scale;
    int           (*sample)[32][36] = state->com.sample;
    int           sblimit = state->com.sblimit;
    short         (*scalefactor)[3][32] = state->com.scalefactor;
    short (*allocation)[32] = state->com.allocation;
    samplefloatrw *smpl_rw = state->smpl_rw;     // out of imdct
    samplefloat *smpl_sb = state->smpl_sb;       // out of subband synth
    int stereo = state->com.stereo;
    short  *m_pOutSamples = state->com.m_pOutSamples;
    unsigned char *alloc_table = state->com.alloc_table;

    pSampl[0] = (*smpl_sb)[0]; pSampl[1] = (*smpl_sb)[1];

    for (ch = 0; ch < stereo; ch++) {
        for (sb = 0; sb < sblimit; sb++) {
            if (allocation[ch][sb] != 0) {
                int idx = alloc_table[sb * 16 + allocation[ch][sb]];
                int x = mp3dec_numbits[idx];
                int xor_coef;
                int *sample_ptr = &sample[ch][sb][0];

                xor_coef = (1 << (x - 1));

                scale = C_quant[idx] * mp3dec_scale_values[scalefactor[ch][0][sb]];
                for (i = 0; i < 12; i++) {
                    (*smpl_rw)[ch][i][sb] =
                        ((float)((sample_ptr[i] ^ xor_coef) << (32 - x) >> 16));

                    // Dequantize the sample
                    (*smpl_rw)[ch][i][sb] += D_quant[idx];
                    (*smpl_rw)[ch][i][sb] *= scale;
                }

                scale = C_quant[idx] * mp3dec_scale_values[scalefactor[ch][1][sb]];
                for (i = 12; i < 18; i++) {
                    (*smpl_rw)[ch][i][sb] =
                        ((float)((sample_ptr[i] ^ xor_coef) << (32 - x) >> 16));

                    // Dequantize the sample
                    (*smpl_rw)[ch][i][sb] += D_quant[idx];
                    (*smpl_rw)[ch][i][sb] *= scale;
                }
            } else {
                for (i = 0; i < 18; i++) {
                    (*smpl_rw)[ch][i][sb] = 0;
                }
            }
        }  // for sb

        for (sb = sblimit; sb < 32; sb++) {
            for (i = 0; i < 18; i++) {
                (*smpl_rw)[ch][i][sb] = 0;
            }
        }

        mp3dec_SubBandSynth(state, ch, 18);
    }    // for ch

    ippsJoin_32f16s_D2L((const float **)pSampl, stereo, 576, m_pOutSamples);

    for (ch = 0; ch < stereo; ch++) {
        for (sb = 0; sb < sblimit; sb++) {
            if (allocation[ch][sb] != 0) {
                int idx = alloc_table[sb * 16 + allocation[ch][sb]];
                int x = mp3dec_numbits[idx];
                int xor_coef;
                int *sample_ptr = &sample[ch][sb][18];

                xor_coef = (1 << (x - 1));

                scale = C_quant[idx] * mp3dec_scale_values[scalefactor[ch][1][sb]];
                for (i = 0; i < 6; i++) {
                    (*smpl_rw)[ch][i][sb] =
                        ((float)((sample_ptr[i] ^ xor_coef) << (32 - x) >> 16));

                    // Dequantize the sample
                    (*smpl_rw)[ch][i][sb] += D_quant[idx];
                    (*smpl_rw)[ch][i][sb] *= scale;
                }

                scale = C_quant[idx] * mp3dec_scale_values[scalefactor[ch][2][sb]];
                for (i = 6; i < 18; i++) {
                    (*smpl_rw)[ch][i][sb] =
                        ((float)((sample_ptr[i] ^ xor_coef) << (32 - x) >> 16));

                    // Dequantize the sample
                    (*smpl_rw)[ch][i][sb] += D_quant[idx];
                    (*smpl_rw)[ch][i][sb] *= scale;
                }
            } else {
                for (i = 0; i < 18; i++) {
                    (*smpl_rw)[ch][i][sb] = 0;
                }
            }
        }  // for sb

        for (sb = sblimit; sb < 32; sb++) {
            for (i = 0; i < 18; i++) {
                (*smpl_rw)[ch][i][sb] = 0;
            }
        }

        mp3dec_SubBandSynth(state, ch, 18);
    }    // for ch

    ippsJoin_32f16s_D2L((const float **)pSampl, stereo, 576, m_pOutSamples + 576 * stereo);

    return 1;
}