i420_rgb8.c 7.25 KB
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/*****************************************************************************
 * i420_rgb8.c : YUV to bitmap RGB conversion module for vlc
 *****************************************************************************
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 * Copyright (C) 2000 VLC authors and VideoLAN
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 * $Id$
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 *
 * Authors: Samuel Hocevar <sam@zoy.org>
 *
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 * This program 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
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU 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 License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
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 *****************************************************************************/

/*****************************************************************************
 * Preamble
 *****************************************************************************/

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#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

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#include <vlc_common.h>
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#include <vlc_filter.h>
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#include <vlc_picture.h>
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#include "i420_rgb.h"
#include "i420_rgb_c.h"

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static void SetOffset( int, int, int, int, bool *, int *, int * );
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/*****************************************************************************
 * I420_RGB8: color YUV 4:2:0 to RGB 8 bpp
 *****************************************************************************/
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void I420_RGB8( filter_t *p_filter, picture_t *p_src, picture_t *p_dest )
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{
    /* We got this one from the old arguments */
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    uint8_t *p_pic = (uint8_t*)p_dest->p->p_pixels;
    uint8_t *p_y   = p_src->Y_PIXELS;
    uint8_t *p_u   = p_src->U_PIXELS;
    uint8_t *p_v   = p_src->V_PIXELS;
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    bool  b_hscale;                         /* horizontal scaling type */
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    int i_vscale;                                 /* vertical scaling type */
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    unsigned int i_x, i_y;                /* horizontal and vertical indexes */
    unsigned int i_real_y;                                          /* y % 4 */
    int          i_right_margin;
    int          i_scale_count;                      /* scale modulo counter */
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    unsigned int i_chroma_width = (p_filter->fmt_in.video.i_x_offset + p_filter->fmt_in.video.i_visible_width) / 2;/* chroma width */
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    /* Lookup table */
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    uint8_t *        p_lookup = p_filter->p_sys->p_base;
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    /* Offset array pointer */
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    int *       p_offset_start = p_filter->p_sys->p_offset;
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    int *       p_offset;

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    const int i_source_margin = p_src->p[0].i_pitch
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                                 - p_src->p[0].i_visible_pitch
                                 - p_filter->fmt_in.video.i_x_offset;
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    const int i_source_margin_c = p_src->p[1].i_pitch
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                                 - p_src->p[1].i_visible_pitch
                                 - ( p_filter->fmt_in.video.i_x_offset / 2 );
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    /* The dithering matrices */
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    static const int dither10[4] = {  0x0,  0x8,  0x2,  0xa };
    static const int dither11[4] = {  0xc,  0x4,  0xe,  0x6 };
    static const int dither12[4] = {  0x3,  0xb,  0x1,  0x9 };
    static const int dither13[4] = {  0xf,  0x7,  0xd,  0x5 };
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    static const int dither20[4] = {  0x0, 0x10,  0x4, 0x14 };
    static const int dither21[4] = { 0x18,  0x8, 0x1c,  0xc };
    static const int dither22[4] = {  0x6, 0x16,  0x2, 0x12 };
    static const int dither23[4] = { 0x1e,  0xe, 0x1a,  0xa };
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    SetOffset( (p_filter->fmt_in.video.i_x_offset + p_filter->fmt_in.video.i_visible_width),
               (p_filter->fmt_in.video.i_y_offset + p_filter->fmt_in.video.i_visible_height),
               (p_filter->fmt_out.video.i_x_offset + p_filter->fmt_out.video.i_visible_width),
               (p_filter->fmt_out.video.i_y_offset + p_filter->fmt_out.video.i_visible_height),
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               &b_hscale, &i_vscale, p_offset_start );

    i_right_margin = p_dest->p->i_pitch - p_dest->p->i_visible_pitch;

    /*
     * Perform conversion
     */
    i_scale_count = ( i_vscale == 1 ) ?
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                    (p_filter->fmt_out.video.i_y_offset + p_filter->fmt_out.video.i_visible_height) :
                    (p_filter->fmt_in.video.i_y_offset + p_filter->fmt_in.video.i_visible_height);
    for( i_y = 0, i_real_y = 0; i_y < (p_filter->fmt_in.video.i_y_offset + p_filter->fmt_in.video.i_visible_height); i_y++ )
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    {
        /* Do horizontal and vertical scaling */
        SCALE_WIDTH_DITHER( 420 );
        SCALE_HEIGHT_DITHER( 420 );
    }
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    p_y += i_source_margin;
    if( i_y % 2 )
    {
        p_u += i_source_margin_c;
        p_v += i_source_margin_c;
    }
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}

/* Following functions are local */

/*****************************************************************************
 * SetOffset: build offset array for conversion functions
 *****************************************************************************
 * This function will build an offset array used in later conversion functions.
 * It will also set horizontal and vertical scaling indicators. The p_offset
 * structure has interleaved Y and U/V offsets.
 *****************************************************************************/
static void SetOffset( int i_width, int i_height, int i_pic_width,
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                       int i_pic_height, bool *pb_hscale,
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                       int *pi_vscale, int *p_offset )
{
    int i_x;                                    /* x position in destination */
    int i_scale_count;                                     /* modulo counter */

    /*
     * Prepare horizontal offset array
     */
    if( i_pic_width - i_width == 0 )
    {
        /* No horizontal scaling: YUV conversion is done directly to picture */
        *pb_hscale = 0;
    }
    else if( i_pic_width - i_width > 0 )
    {
        int i_dummy = 0;

        /* Prepare scaling array for horizontal extension */
        *pb_hscale = 1;
        i_scale_count = i_pic_width;
        for( i_x = i_width; i_x--; )
        {
            while( (i_scale_count -= i_width) > 0 )
            {
                *p_offset++ = 0;
                *p_offset++ = 0;
            }
            *p_offset++ = 1;
            *p_offset++ = i_dummy;
            i_dummy = 1 - i_dummy;
            i_scale_count += i_pic_width;
        }
    }
    else /* if( i_pic_width - i_width < 0 ) */
    {
        int i_remainder = 0;
        int i_jump;

        /* Prepare scaling array for horizontal reduction */
        *pb_hscale = 1;
        i_scale_count = i_width;
        for( i_x = i_pic_width; i_x--; )
        {
            i_jump = 1;
            while( (i_scale_count -= i_pic_width) > 0 )
            {
                i_jump += 1;
            }
            *p_offset++ = i_jump;
            *p_offset++ = ( i_jump += i_remainder ) >> 1;
            i_remainder = i_jump & 1;
            i_scale_count += i_width;
        }
    }

    /*
     * Set vertical scaling indicator
     */
    if( i_pic_height - i_height == 0 )
    {
        *pi_vscale = 0;
    }
    else if( i_pic_height - i_height > 0 )
    {
        *pi_vscale = 1;
    }
    else /* if( i_pic_height - i_height < 0 ) */
    {
        *pi_vscale = -1;
    }
}