annotate ffmpeg/libavcodec/wmv2dsp.c @ 13:844d341cf643 tip

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/*
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "libavutil/attributes.h"
#include "libavutil/common.h"
#include "avcodec.h"
#include "dsputil.h"
#include "wmv2dsp.h"

#define W0 2048
#define W1 2841 /* 2048*sqrt (2)*cos (1*pi/16) */
#define W2 2676 /* 2048*sqrt (2)*cos (2*pi/16) */
#define W3 2408 /* 2048*sqrt (2)*cos (3*pi/16) */
#define W4 2048 /* 2048*sqrt (2)*cos (4*pi/16) */
#define W5 1609 /* 2048*sqrt (2)*cos (5*pi/16) */
#define W6 1108 /* 2048*sqrt (2)*cos (6*pi/16) */
#define W7 565  /* 2048*sqrt (2)*cos (7*pi/16) */

static void wmv2_idct_row(short * b)
{
    int s1, s2;
    int a0, a1, a2, a3, a4, a5, a6, a7;

    /* step 1 */
    a1 = W1 * b[1] + W7 * b[7];
    a7 = W7 * b[1] - W1 * b[7];
    a5 = W5 * b[5] + W3 * b[3];
    a3 = W3 * b[5] - W5 * b[3];
    a2 = W2 * b[2] + W6 * b[6];
    a6 = W6 * b[2] - W2 * b[6];
    a0 = W0 * b[0] + W0 * b[4];
    a4 = W0 * b[0] - W0 * b[4];

    /* step 2 */
    s1 = (181 * (a1 - a5 + a7 - a3) + 128) >> 8; // 1, 3, 5, 7
    s2 = (181 * (a1 - a5 - a7 + a3) + 128) >> 8;

    /* step 3 */
    b[0] = (a0 + a2 + a1 + a5 + (1 << 7)) >> 8;
    b[1] = (a4 + a6 + s1      + (1 << 7)) >> 8;
    b[2] = (a4 - a6 + s2      + (1 << 7)) >> 8;
    b[3] = (a0 - a2 + a7 + a3 + (1 << 7)) >> 8;
    b[4] = (a0 - a2 - a7 - a3 + (1 << 7)) >> 8;
    b[5] = (a4 - a6 - s2      + (1 << 7)) >> 8;
    b[6] = (a4 + a6 - s1      + (1 << 7)) >> 8;
    b[7] = (a0 + a2 - a1 - a5 + (1 << 7)) >> 8;
}

static void wmv2_idct_col(short * b)
{
    int s1, s2;
    int a0, a1, a2, a3, a4, a5, a6, a7;

    /* step 1, with extended precision */
    a1 = (W1 * b[8 * 1] + W7 * b[8 * 7] + 4) >> 3;
    a7 = (W7 * b[8 * 1] - W1 * b[8 * 7] + 4) >> 3;
    a5 = (W5 * b[8 * 5] + W3 * b[8 * 3] + 4) >> 3;
    a3 = (W3 * b[8 * 5] - W5 * b[8 * 3] + 4) >> 3;
    a2 = (W2 * b[8 * 2] + W6 * b[8 * 6] + 4) >> 3;
    a6 = (W6 * b[8 * 2] - W2 * b[8 * 6] + 4) >> 3;
    a0 = (W0 * b[8 * 0] + W0 * b[8 * 4]    ) >> 3;
    a4 = (W0 * b[8 * 0] - W0 * b[8 * 4]    ) >> 3;

    /* step 2 */
    s1 = (181 * (a1 - a5 + a7 - a3) + 128) >> 8;
    s2 = (181 * (a1 - a5 - a7 + a3) + 128) >> 8;

    /* step 3 */
    b[8 * 0] = (a0 + a2 + a1 + a5 + (1 << 13)) >> 14;
    b[8 * 1] = (a4 + a6 + s1      + (1 << 13)) >> 14;
    b[8 * 2] = (a4 - a6 + s2      + (1 << 13)) >> 14;
    b[8 * 3] = (a0 - a2 + a7 + a3 + (1 << 13)) >> 14;

    b[8 * 4] = (a0 - a2 - a7 - a3 + (1 << 13)) >> 14;
    b[8 * 5] = (a4 - a6 - s2      + (1 << 13)) >> 14;
    b[8 * 6] = (a4 + a6 - s1      + (1 << 13)) >> 14;
    b[8 * 7] = (a0 + a2 - a1 - a5 + (1 << 13)) >> 14;
}

static void wmv2_idct_add_c(uint8_t *dest, int line_size, int16_t *block)
{
    int i;

    for (i = 0; i < 64; i += 8)
        wmv2_idct_row(block + i);
    for (i = 0; i < 8; i++)
        wmv2_idct_col(block + i);

    for (i = 0; i < 8; i++) {
        dest[0] = av_clip_uint8(dest[0] + block[0]);
        dest[1] = av_clip_uint8(dest[1] + block[1]);
        dest[2] = av_clip_uint8(dest[2] + block[2]);
        dest[3] = av_clip_uint8(dest[3] + block[3]);
        dest[4] = av_clip_uint8(dest[4] + block[4]);
        dest[5] = av_clip_uint8(dest[5] + block[5]);
        dest[6] = av_clip_uint8(dest[6] + block[6]);
        dest[7] = av_clip_uint8(dest[7] + block[7]);
        dest += line_size;
        block += 8;
    }
}

static void wmv2_idct_put_c(uint8_t *dest, int line_size, int16_t *block)
{
    int i;

    for (i = 0; i < 64; i += 8)
        wmv2_idct_row(block + i);
    for (i = 0; i < 8; i++)
        wmv2_idct_col(block + i);

    for (i = 0; i < 8; i++) {
        dest[0] = av_clip_uint8(block[0]);
        dest[1] = av_clip_uint8(block[1]);
        dest[2] = av_clip_uint8(block[2]);
        dest[3] = av_clip_uint8(block[3]);
        dest[4] = av_clip_uint8(block[4]);
        dest[5] = av_clip_uint8(block[5]);
        dest[6] = av_clip_uint8(block[6]);
        dest[7] = av_clip_uint8(block[7]);
        dest += line_size;
        block += 8;
    }
}

av_cold void ff_wmv2dsp_init(WMV2DSPContext *c)
{
    c->idct_add  = wmv2_idct_add_c;
    c->idct_put  = wmv2_idct_put_c;
    c->idct_perm = FF_NO_IDCT_PERM;
}