i420_rgb8.c

video linux conference

/*****************************************************************************
 * i420_rgb8.c : YUV to bitmap RGB conversion module for vlc
 *****************************************************************************
 * Copyright (C) 2000 VideoLAN
 * $Id: i420_rgb8.c 10101 2005-03-02 16:47:31Z robux4 $
 *
 * Authors: Samuel Hocevar <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 *****************************************************************************/

/*****************************************************************************
 * Preamble
 *****************************************************************************/
#include <string.h>                                            /* strerror() */
#include <stdlib.h>                                      /* malloc(), free() */

#include <vlc/vlc.h>
#include <vlc/vout.h>

#include "i420_rgb.h"
#include "i420_rgb_c.h"

static void SetOffset( int, int, int, int, vlc_bool_t *, int *, int * );

/*****************************************************************************
 * I420_RGB8: color YUV 4:2:0 to RGB 8 bpp
 *****************************************************************************/
void E_(I420_RGB8)( vout_thread_t *p_vout, picture_t *p_src, picture_t *p_dest )
{
    /* We got this one from the old arguments */
    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;

    vlc_bool_t  b_hscale;                         /* horizontal scaling type */
    unsigned int i_vscale;                          /* vertical scaling type */
    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 */
    unsigned int i_chroma_width = p_vout->render.i_width / 2;/* chroma width */

    /* Lookup table */
    uint8_t *        p_lookup = p_vout->chroma.p_sys->p_base;

    /* Offset array pointer */
    int *       p_offset_start = p_vout->chroma.p_sys->p_offset;
    int *       p_offset;

    const int i_source_margin = p_src->p[0].i_pitch
                                 - p_src->p[0].i_visible_pitch;
    const int i_source_margin_c = p_src->p[1].i_pitch
                                 - p_src->p[1].i_visible_pitch;

    /* The dithering matrices */
    static int dither10[4] = {  0x0,  0x8,  0x2,  0xa };
    static int dither11[4] = {  0xc,  0x4,  0xe,  0x6 };
    static int dither12[4] = {  0x3,  0xb,  0x1,  0x9 };
    static int dither13[4] = {  0xf,  0x7,  0xd,  0x5 };

    static int dither20[4] = {  0x0, 0x10,  0x4, 0x14 };
    static int dither21[4] = { 0x18,  0x8, 0x1c,  0xc };
    static int dither22[4] = {  0x6, 0x16,  0x2, 0x12 };
    static int dither23[4] = { 0x1e,  0xe, 0x1a,  0xa };

    SetOffset( p_vout->render.i_width, p_vout->render.i_height,
               p_vout->output.i_width, p_vout->output.i_height,
               &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 ) ?
                    p_vout->output.i_height : p_vout->render.i_height;
    for( i_y = 0, i_real_y = 0; i_y < p_vout->render.i_height; i_y++ )
    {
        /* Do horizontal and vertical scaling */
        SCALE_WIDTH_DITHER( 420 );
        SCALE_HEIGHT_DITHER( 420 );
    }

    p_y += i_source_margin;
    if( i_y % 2 )
    {
        p_u += i_source_margin_c;
        p_v += i_source_margin_c;
    }
}

/* 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,
                       int i_pic_height, vlc_bool_t *pb_hscale,
                       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;
    }
}