FFmpeg: libavcodec/dcadsp.c Source File

00001 /*
00002  * Copyright (c) 2004 Gildas Bazin
00003  * Copyright (c) 2010 Mans Rullgard <mans@mansr.com>
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "config.h"
00023 #include "dcadsp.h"
00024 
00025 static void dca_lfe_fir_c(float *out, const float *in, const float *coefs,
00026                           int decifactor, float scale)
00027 {
00028     float *out2 = out + decifactor;
00029     const float *cf0 = coefs;
00030     const float *cf1 = coefs + 256;
00031     int j, k;
00032 
00033     /* One decimated sample generates 2*decifactor interpolated ones */
00034     for (k = 0; k < decifactor; k++) {
00035         float v0 = 0.0;
00036         float v1 = 0.0;
00037         for (j = 0; j < 256 / decifactor; j++) {
00038             float s = in[-j];
00039             v0 += s * *cf0++;
00040             v1 += s * *--cf1;
00041         }
00042         *out++  = v0 * scale;
00043         *out2++ = v1 * scale;
00044     }
00045 }
00046 
00047 void ff_dcadsp_init(DCADSPContext *s)
00048 {
00049     s->lfe_fir = dca_lfe_fir_c;
00050     if (ARCH_ARM) ff_dcadsp_init_arm(s);
00051 }