modules/video_chroma/i420_rgb8.c

   1 /*****************************************************************************
   2  * i420_rgb8.c : YUV to bitmap RGB conversion module for vlc
   3  *****************************************************************************
   4  * Copyright (C) 2000 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Samuel Hocevar <sam@zoy.org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with this program; if not, write to the Free Software Foundation,
  21  * 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 #include <vlc_picture.h>
  35
  36 #include "i420_rgb.h"
  37 #include "i420_rgb_c.h"
  38
  39 static void SetOffset( int, int, int, int, bool *, int *, int * );
  40
  41 /*****************************************************************************
  42  * I420_RGB8: color YUV 4:2:0 to RGB 8 bpp
  43  *****************************************************************************/
  44 void I420_RGB8( filter_t *p_filter, picture_t *p_src, picture_t *p_dest )
  45 {
  46     /* We got this one from the old arguments */
  47     uint8_t *p_pic = (uint8_t*)p_dest->p->p_pixels;
  48     uint8_t *p_y   = p_src->Y_PIXELS;
  49     uint8_t *p_u   = p_src->U_PIXELS;
  50     uint8_t *p_v   = p_src->V_PIXELS;
  51
  52     bool  b_hscale;                         /* horizontal scaling type */
  53     int i_vscale;                                 /* vertical scaling type */
  54     unsigned int i_x, i_y;                /* horizontal and vertical indexes */
  55     unsigned int i_real_y;                                          /* y % 4 */
  56     int          i_right_margin;
  57     int          i_scale_count;                      /* scale modulo counter */
  58     unsigned int i_chroma_width = (p_filter->fmt_in.video.i_x_offset + p_filter->fmt_in.video.i_visible_width) / 2;/* chroma width */
  59
  60     /* Lookup table */
  61     uint8_t *        p_lookup = p_filter->p_sys->p_base;
  62
  63     /* Offset array pointer */
  64     int *       p_offset_start = p_filter->p_sys->p_offset;
  65     int *       p_offset;
  66
  67     const int i_source_margin = p_src->p[0].i_pitch
  68                                  - p_src->p[0].i_visible_pitch
  69                                  - p_filter->fmt_in.video.i_x_offset;
  70     const int i_source_margin_c = p_src->p[1].i_pitch
  71                                  - p_src->p[1].i_visible_pitch
  72                                  - ( p_filter->fmt_in.video.i_x_offset / 2 );
  73
  74     /* The dithering matrices */
  75     static const int dither10[4] = {  0x0,  0x8,  0x2,  0xa };
  76     static const int dither11[4] = {  0xc,  0x4,  0xe,  0x6 };
  77     static const int dither12[4] = {  0x3,  0xb,  0x1,  0x9 };
  78     static const int dither13[4] = {  0xf,  0x7,  0xd,  0x5 };
  79
  80     static const int dither20[4] = {  0x0, 0x10,  0x4, 0x14 };
  81     static const int dither21[4] = { 0x18,  0x8, 0x1c,  0xc };
  82     static const int dither22[4] = {  0x6, 0x16,  0x2, 0x12 };
  83     static const int dither23[4] = { 0x1e,  0xe, 0x1a,  0xa };
  84
  85     SetOffset( (p_filter->fmt_in.video.i_x_offset + p_filter->fmt_in.video.i_visible_width),
  86                (p_filter->fmt_in.video.i_y_offset + p_filter->fmt_in.video.i_visible_height),
  87                (p_filter->fmt_out.video.i_x_offset + p_filter->fmt_out.video.i_visible_width),
  88                (p_filter->fmt_out.video.i_y_offset + p_filter->fmt_out.video.i_visible_height),
  89                &b_hscale, &i_vscale, p_offset_start );
  90
  91     i_right_margin = p_dest->p->i_pitch - p_dest->p->i_visible_pitch;
  92
  93     /*
  94      * Perform conversion
  95      */
  96     i_scale_count = ( i_vscale == 1 ) ?
  97                     (p_filter->fmt_out.video.i_y_offset + p_filter->fmt_out.video.i_visible_height) :
  98                     (p_filter->fmt_in.video.i_y_offset + p_filter->fmt_in.video.i_visible_height);
  99     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++ )
 100     {
 101         /* Do horizontal and vertical scaling */
 102         SCALE_WIDTH_DITHER( 420 );
 103         SCALE_HEIGHT_DITHER( 420 );
 104     }
 105
 106     p_y += i_source_margin;
 107     if( i_y % 2 )
 108     {
 109         p_u += i_source_margin_c;
 110         p_v += i_source_margin_c;
 111     }
 112 }
 113
 114 /* Following functions are local */
 115
 116 /*****************************************************************************
 117  * SetOffset: build offset array for conversion functions
 118  *****************************************************************************
 119  * This function will build an offset array used in later conversion functions.
 120  * It will also set horizontal and vertical scaling indicators. The p_offset
 121  * structure has interleaved Y and U/V offsets.
 122  *****************************************************************************/
 123 static void SetOffset( int i_width, int i_height, int i_pic_width,
 124                        int i_pic_height, bool *pb_hscale,
 125                        int *pi_vscale, int *p_offset )
 126 {
 127     int i_x;                                    /* x position in destination */
 128     int i_scale_count;                                     /* modulo counter */
 129
 130     /*
 131      * Prepare horizontal offset array
 132      */
 133     if( i_pic_width - i_width == 0 )
 134     {
 135         /* No horizontal scaling: YUV conversion is done directly to picture */
 136         *pb_hscale = 0;
 137     }
 138     else if( i_pic_width - i_width > 0 )
 139     {
 140         int i_dummy = 0;
 141
 142         /* Prepare scaling array for horizontal extension */
 143         *pb_hscale = 1;
 144         i_scale_count = i_pic_width;
 145         for( i_x = i_width; i_x--; )
 146         {
 147             while( (i_scale_count -= i_width) > 0 )
 148             {
 149                 *p_offset++ = 0;
 150                 *p_offset++ = 0;
 151             }
 152             *p_offset++ = 1;
 153             *p_offset++ = i_dummy;
 154             i_dummy = 1 - i_dummy;
 155             i_scale_count += i_pic_width;
 156         }
 157     }
 158     else /* if( i_pic_width - i_width < 0 ) */
 159     {
 160         int i_remainder = 0;
 161         int i_jump;
 162
 163         /* Prepare scaling array for horizontal reduction */
 164         *pb_hscale = 1;
 165         i_scale_count = i_width;
 166         for( i_x = i_pic_width; i_x--; )
 167         {
 168             i_jump = 1;
 169             while( (i_scale_count -= i_pic_width) > 0 )
 170             {
 171                 i_jump += 1;
 172             }
 173             *p_offset++ = i_jump;
 174             *p_offset++ = ( i_jump += i_remainder ) >> 1;
 175             i_remainder = i_jump & 1;
 176             i_scale_count += i_width;
 177         }
 178     }
 179
 180     /*
 181      * Set vertical scaling indicator
 182      */
 183     if( i_pic_height - i_height == 0 )
 184     {
 185         *pi_vscale = 0;
 186     }
 187     else if( i_pic_height - i_height > 0 )
 188     {
 189         *pi_vscale = 1;
 190     }
 191     else /* if( i_pic_height - i_height < 0 ) */
 192     {
 193         *pi_vscale = -1;
 194     }
 195 }
 196