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  *
   6  * Authors: Samuel Hocevar <sam@zoy.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 /*****************************************************************************
  24  * Preamble
  25  *****************************************************************************/
  26
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <vlc_common.h>
  32 #include <vlc_filter.h>
  33 #include <vlc_picture.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     filter_sys_t *p_sys = p_filter->p_sys;
  46
  47     /* We got this one from the old arguments */
  48     uint8_t *p_pic = (uint8_t*)p_dest->p->p_pixels;
  49     uint8_t *p_y   = p_src->Y_PIXELS;
  50     uint8_t *p_u   = p_src->U_PIXELS;
  51     uint8_t *p_v   = p_src->V_PIXELS;
  52
  53     bool  b_hscale;                         /* horizontal scaling type */
  54     int i_vscale;                                 /* vertical scaling type */
  55     unsigned int i_x, i_y;                /* horizontal and vertical indexes */
  56     unsigned int i_real_y;                                          /* y % 4 */
  57     int          i_right_margin;
  58     int          i_scale_count;                      /* scale modulo counter */
  59     unsigned int i_chroma_width = (p_filter->fmt_in.video.i_x_offset + p_filter->fmt_in.video.i_visible_width) / 2;/* chroma width */
  60
  61     /* Lookup table */
  62     uint8_t *        p_lookup = p_sys->p_base;
  63
  64     /* Offset array pointer */
  65     int *       p_offset_start = p_sys->p_offset;
  66     int *       p_offset;
  67
  68     const int i_source_margin = p_src->p[0].i_pitch
  69                                  - p_src->p[0].i_visible_pitch
  70                                  - p_filter->fmt_in.video.i_x_offset;
  71     const int i_source_margin_c = p_src->p[1].i_pitch
  72                                  - p_src->p[1].i_visible_pitch
  73                                  - ( p_filter->fmt_in.video.i_x_offset / 2 );
  74
  75     /* The dithering matrices */
  76     static const int dither10[4] = {  0x0,  0x8,  0x2,  0xa };
  77     static const int dither11[4] = {  0xc,  0x4,  0xe,  0x6 };
  78     static const int dither12[4] = {  0x3,  0xb,  0x1,  0x9 };
  79     static const int dither13[4] = {  0xf,  0x7,  0xd,  0x5 };
  80
  81     static const int dither20[4] = {  0x0, 0x10,  0x4, 0x14 };
  82     static const int dither21[4] = { 0x18,  0x8, 0x1c,  0xc };
  83     static const int dither22[4] = {  0x6, 0x16,  0x2, 0x12 };
  84     static const int dither23[4] = { 0x1e,  0xe, 0x1a,  0xa };
  85
  86     SetOffset( (p_filter->fmt_in.video.i_x_offset + p_filter->fmt_in.video.i_visible_width),
  87                (p_filter->fmt_in.video.i_y_offset + p_filter->fmt_in.video.i_visible_height),
  88                (p_filter->fmt_out.video.i_x_offset + p_filter->fmt_out.video.i_visible_width),
  89                (p_filter->fmt_out.video.i_y_offset + p_filter->fmt_out.video.i_visible_height),
  90                &b_hscale, &i_vscale, p_offset_start );
  91
  92     i_right_margin = p_dest->p->i_pitch - p_dest->p->i_visible_pitch;
  93
  94     /*
  95      * Perform conversion
  96      */
  97     i_scale_count = ( i_vscale == 1 ) ?
  98                     (p_filter->fmt_out.video.i_y_offset + p_filter->fmt_out.video.i_visible_height) :
  99                     (p_filter->fmt_in.video.i_y_offset + p_filter->fmt_in.video.i_visible_height);
 100     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++ )
 101     {
 102         /* Do horizontal and vertical scaling */
 103         SCALE_WIDTH_DITHER( 420 );
 104         SCALE_HEIGHT_DITHER( 420 );
 105     }
 106
 107     p_y += i_source_margin;
 108     if( i_y % 2 )
 109     {
 110         p_u += i_source_margin_c;
 111         p_v += i_source_margin_c;
 112     }
 113 }
 114
 115 /* Following functions are local */
 116
 117 /*****************************************************************************
 118  * SetOffset: build offset array for conversion functions
 119  *****************************************************************************
 120  * This function will build an offset array used in later conversion functions.
 121  * It will also set horizontal and vertical scaling indicators. The p_offset
 122  * structure has interleaved Y and U/V offsets.
 123  *****************************************************************************/
 124 static void SetOffset( int i_width, int i_height, int i_pic_width,
 125                        int i_pic_height, bool *pb_hscale,
 126                        int *pi_vscale, int *p_offset )
 127 {
 128     int i_x;                                    /* x position in destination */
 129     int i_scale_count;                                     /* modulo counter */
 130
 131     /*
 132      * Prepare horizontal offset array
 133      */
 134     if( i_pic_width - i_width == 0 )
 135     {
 136         /* No horizontal scaling: YUV conversion is done directly to picture */
 137         *pb_hscale = 0;
 138     }
 139     else if( i_pic_width - i_width > 0 )
 140     {
 141         int i_dummy = 0;
 142
 143         /* Prepare scaling array for horizontal extension */
 144         *pb_hscale = 1;
 145         i_scale_count = i_pic_width;
 146         for( i_x = i_width; i_x--; )
 147         {
 148             while( (i_scale_count -= i_width) > 0 )
 149             {
 150                 *p_offset++ = 0;
 151                 *p_offset++ = 0;
 152             }
 153             *p_offset++ = 1;
 154             *p_offset++ = i_dummy;
 155             i_dummy = 1 - i_dummy;
 156             i_scale_count += i_pic_width;
 157         }
 158     }
 159     else /* if( i_pic_width - i_width < 0 ) */
 160     {
 161         int i_remainder = 0;
 162         int i_jump;
 163
 164         /* Prepare scaling array for horizontal reduction */
 165         *pb_hscale = 1;
 166         i_scale_count = i_width;
 167         for( i_x = i_pic_width; i_x--; )
 168         {
 169             i_jump = 1;
 170             while( (i_scale_count -= i_pic_width) > 0 )
 171             {
 172                 i_jump += 1;
 173             }
 174             *p_offset++ = i_jump;
 175             *p_offset++ = ( i_jump += i_remainder ) >> 1;
 176             i_remainder = i_jump & 1;
 177             i_scale_count += i_width;
 178         }
 179     }
 180
 181     /*
 182      * Set vertical scaling indicator
 183      */
 184     if( i_pic_height - i_height == 0 )
 185     {
 186         *pi_vscale = 0;
 187     }
 188     else if( i_pic_height - i_height > 0 )
 189     {
 190         *pi_vscale = 1;
 191     }
 192     else /* if( i_pic_height - i_height < 0 ) */
 193     {
 194         *pi_vscale = -1;
 195     }
 196 }
 197