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ffmpeg / libavcodec / synth_filter.c @ 80ba1ddb

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/*
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 * copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "fft.h"
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#include "synth_filter.h"
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static void synth_filter_float(FFTContext *imdct,
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                           float *synth_buf_ptr, int *synth_buf_offset,
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                           float synth_buf2[32], const float window[512],
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                           float out[32], const float in[32], float scale)
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{
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    float *synth_buf= synth_buf_ptr + *synth_buf_offset;
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    int i, j;
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    ff_imdct_half(imdct, synth_buf, in);
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    for (i = 0; i < 16; i++){
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        float a= synth_buf2[i     ];
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        float b= synth_buf2[i + 16];
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        float c= 0;
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        float d= 0;
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        for (j = 0; j < 512 - *synth_buf_offset; j += 64){
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            a += window[i + j     ]*(-synth_buf[15 - i + j      ]);
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            b += window[i + j + 16]*( synth_buf[     i + j      ]);
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            c += window[i + j + 32]*( synth_buf[16 + i + j      ]);
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            d += window[i + j + 48]*( synth_buf[31 - i + j      ]);
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        }
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        for (     ; j < 512; j += 64){
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            a += window[i + j     ]*(-synth_buf[15 - i + j - 512]);
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            b += window[i + j + 16]*( synth_buf[     i + j - 512]);
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            c += window[i + j + 32]*( synth_buf[16 + i + j - 512]);
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            d += window[i + j + 48]*( synth_buf[31 - i + j - 512]);
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        }
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        out[i     ] = a*scale;
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        out[i + 16] = b*scale;
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        synth_buf2[i     ] = c;
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        synth_buf2[i + 16] = d;
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    }
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    *synth_buf_offset= (*synth_buf_offset - 32)&511;
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}
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av_cold void ff_synth_filter_init(SynthFilterContext *c)
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{
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    c->synth_filter_float = synth_filter_float;
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    if (ARCH_ARM) ff_synth_filter_init_arm(c);
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}