modules/video_chroma/i420_rgb8.c

   1 /*****************************************************************************
   2  * i420_rgb8.c : YUV to bitmap RGB conversion module for vlc
   3  *****************************************************************************
   4  * Copyright (C) 2000 the VideoLAN team
   5  * $Id$
   6  *
   7  * Authors: Samuel Hocevar <sam@zoy.org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 /*****************************************************************************
  25  * Preamble
  26  *****************************************************************************/
  27
  28 #ifdef HAVE_CONFIG_H
  29 # include "config.h"
  30 #endif
  31
  32 #include <vlc_common.h>
  33 #include <vlc_filter.h>
  34
  35 #include "i420_rgb.h"
  36 #include "i420_rgb_c.h"
  37
  38 static void SetOffset( int, int, int, int, bool *, int *, int * );
  39
  40 /*****************************************************************************
  41  * I420_RGB8: color YUV 4:2:0 to RGB 8 bpp
  42  *****************************************************************************/
  43 void I420_RGB8( filter_t *p_filter, picture_t *p_src, picture_t *p_dest )
  44 {
  45     /* We got this one from the old arguments */
  46     uint8_t *p_pic = (uint8_t*)p_dest->p->p_pixels;
  47     uint8_t *p_y   = p_src->Y_PIXELS;
  48     uint8_t *p_u   = p_src->U_PIXELS;
  49     uint8_t *p_v   = p_src->V_PIXELS;
  50
  51     bool  b_hscale;                         /* horizontal scaling type */
  52     int i_vscale;                                 /* vertical scaling type */
  53     unsigned int i_x, i_y;                /* horizontal and vertical indexes */
  54     unsigned int i_real_y;                                          /* y % 4 */
  55     int          i_right_margin;
  56     int          i_scale_count;                      /* scale modulo counter */
  57     unsigned int i_chroma_width = p_filter->fmt_in.video.i_width / 2;/* chroma width */
  58
  59     /* Lookup table */
  60     uint8_t *        p_lookup = p_filter->p_sys->p_base;
  61
  62     /* Offset array pointer */
  63     int *       p_offset_start = p_filter->p_sys->p_offset;
  64     int *       p_offset;
  65
  66     const int i_source_margin = p_src->p[0].i_pitch
  67                                  - p_src->p[0].i_visible_pitch;
  68     const int i_source_margin_c = p_src->p[1].i_pitch
  69                                  - p_src->p[1].i_visible_pitch;
  70
  71     /* The dithering matrices */
  72     static const int dither10[4] = {  0x0,  0x8,  0x2,  0xa };
  73     static const int dither11[4] = {  0xc,  0x4,  0xe,  0x6 };
  74     static const int dither12[4] = {  0x3,  0xb,  0x1,  0x9 };
  75     static const int dither13[4] = {  0xf,  0x7,  0xd,  0x5 };
  76
  77     static const int dither20[4] = {  0x0, 0x10,  0x4, 0x14 };
  78     static const int dither21[4] = { 0x18,  0x8, 0x1c,  0xc };
  79     static const int dither22[4] = {  0x6, 0x16,  0x2, 0x12 };
  80     static const int dither23[4] = { 0x1e,  0xe, 0x1a,  0xa };
  81
  82     SetOffset( p_filter->fmt_in.video.i_width,
  83                p_filter->fmt_in.video.i_height,
  84                p_filter->fmt_out.video.i_width,
  85                p_filter->fmt_out.video.i_height,
  86                &b_hscale, &i_vscale, p_offset_start );
  87
  88     i_right_margin = p_dest->p->i_pitch - p_dest->p->i_visible_pitch;
  89
  90     /*
  91      * Perform conversion
  92      */
  93     i_scale_count = ( i_vscale == 1 ) ?
  94                     p_filter->fmt_out.video.i_height :
  95                     p_filter->fmt_in.video.i_height;
  96     for( i_y = 0, i_real_y = 0; i_y < p_filter->fmt_in.video.i_height; i_y++ )
  97     {
  98         /* Do horizontal and vertical scaling */
  99         SCALE_WIDTH_DITHER( 420 );
 100         SCALE_HEIGHT_DITHER( 420 );
 101     }
 102
 103     p_y += i_source_margin;
 104     if( i_y % 2 )
 105     {
 106         p_u += i_source_margin_c;
 107         p_v += i_source_margin_c;
 108     }
 109 }
 110
 111 /* Following functions are local */
 112
 113 /*****************************************************************************
 114  * SetOffset: build offset array for conversion functions
 115  *****************************************************************************
 116  * This function will build an offset array used in later conversion functions.
 117  * It will also set horizontal and vertical scaling indicators. The p_offset
 118  * structure has interleaved Y and U/V offsets.
 119  *****************************************************************************/
 120 static void SetOffset( int i_width, int i_height, int i_pic_width,
 121                        int i_pic_height, bool *pb_hscale,
 122                        int *pi_vscale, int *p_offset )
 123 {
 124     int i_x;                                    /* x position in destination */
 125     int i_scale_count;                                     /* modulo counter */
 126
 127     /*
 128      * Prepare horizontal offset array
 129      */
 130     if( i_pic_width - i_width == 0 )
 131     {
 132         /* No horizontal scaling: YUV conversion is done directly to picture */
 133         *pb_hscale = 0;
 134     }
 135     else if( i_pic_width - i_width > 0 )
 136     {
 137         int i_dummy = 0;
 138
 139         /* Prepare scaling array for horizontal extension */
 140         *pb_hscale = 1;
 141         i_scale_count = i_pic_width;
 142         for( i_x = i_width; i_x--; )
 143         {
 144             while( (i_scale_count -= i_width) > 0 )
 145             {
 146                 *p_offset++ = 0;
 147                 *p_offset++ = 0;
 148             }
 149             *p_offset++ = 1;
 150             *p_offset++ = i_dummy;
 151             i_dummy = 1 - i_dummy;
 152             i_scale_count += i_pic_width;
 153         }
 154     }
 155     else /* if( i_pic_width - i_width < 0 ) */
 156     {
 157         int i_remainder = 0;
 158         int i_jump;
 159
 160         /* Prepare scaling array for horizontal reduction */
 161         *pb_hscale = 1;
 162         i_scale_count = i_width;
 163         for( i_x = i_pic_width; i_x--; )
 164         {
 165             i_jump = 1;
 166             while( (i_scale_count -= i_pic_width) > 0 )
 167             {
 168                 i_jump += 1;
 169             }
 170             *p_offset++ = i_jump;
 171             *p_offset++ = ( i_jump += i_remainder ) >> 1;
 172             i_remainder = i_jump & 1;
 173             i_scale_count += i_width;
 174         }
 175     }
 176
 177     /*
 178      * Set vertical scaling indicator
 179      */
 180     if( i_pic_height - i_height == 0 )
 181     {
 182         *pi_vscale = 0;
 183     }
 184     else if( i_pic_height - i_height > 0 )
 185     {
 186         *pi_vscale = 1;
 187     }
 188     else /* if( i_pic_height - i_height < 0 ) */
 189     {
 190         *pi_vscale = -1;
 191     }
 192 }
 193