blend.c

video linux conference

/*****************************************************************************
 * blend.c: alpha blend 2 pictures together
 *****************************************************************************
 * Copyright (C) 2003 VideoLAN
 * $Id: blend.c 10101 2005-03-02 16:47:31Z robux4 $
 *
 * Author: Gildas Bazin <[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 <vlc/vlc.h>
#include <vlc/decoder.h>
#include "vlc_filter.h"

/*****************************************************************************
 * filter_sys_t : filter descriptor
 *****************************************************************************/
struct filter_sys_t
{
    int i_dummy;
};

/****************************************************************************
 * Local prototypes
 ****************************************************************************/
static int  OpenFilter ( vlc_object_t * );
static void CloseFilter( vlc_object_t * );

/* TODO i_alpha support for BlendR16 */
static void Blend( filter_t *, picture_t *, picture_t *, picture_t *,
                   int, int, int );
static void BlendI420( filter_t *, picture_t *, picture_t *, picture_t *,
                       int, int, int, int, int );
static void BlendR16( filter_t *, picture_t *, picture_t *, picture_t *,
                      int, int, int, int, int );
static void BlendR24( filter_t *, picture_t *, picture_t *, picture_t *,
                      int, int, int, int, int );
static void BlendYUY2( filter_t *, picture_t *, picture_t *, picture_t *,
                       int, int, int, int, int );
static void BlendPalI420( filter_t *, picture_t *, picture_t *, picture_t *,
                          int, int, int, int, int );
static void BlendPalYUY2( filter_t *, picture_t *, picture_t *, picture_t *,
                          int, int, int, int, int );
static void BlendPalRV( filter_t *, picture_t *, picture_t *, picture_t *,
                        int, int, int, int, int );

/*****************************************************************************
 * Module descriptor
 *****************************************************************************/
vlc_module_begin();
    set_description( _("Video pictures blending") );
    set_category( CAT_VIDEO );
    set_subcategory( SUBCAT_VIDEO_VFILTER );
    set_capability( "video blending", 100 );
    set_callbacks( OpenFilter, CloseFilter );
vlc_module_end();

/*****************************************************************************
 * OpenFilter: probe the filter and return score
 *****************************************************************************/
static int OpenFilter( vlc_object_t *p_this )
{
    filter_t *p_filter = (filter_t*)p_this;
    filter_sys_t *p_sys;

    /* Check if we can handle that format.
     * We could try to use a chroma filter if we can't. */
    if( ( p_filter->fmt_in.video.i_chroma != VLC_FOURCC('Y','U','V','A') &&
          p_filter->fmt_in.video.i_chroma != VLC_FOURCC('Y','U','V','P') ) ||
        ( p_filter->fmt_out.video.i_chroma != VLC_FOURCC('I','4','2','0') &&
          p_filter->fmt_out.video.i_chroma != VLC_FOURCC('Y','U','Y','2') &&
          p_filter->fmt_out.video.i_chroma != VLC_FOURCC('Y','V','1','2') &&
          p_filter->fmt_out.video.i_chroma != VLC_FOURCC('R','V','1','6') &&
          p_filter->fmt_out.video.i_chroma != VLC_FOURCC('R','V','2','4') &&
          p_filter->fmt_out.video.i_chroma != VLC_FOURCC('R','V','3','2') ) )
    {
        return VLC_EGENERIC;
    }

    /* Allocate the memory needed to store the decoder's structure */
    if( ( p_filter->p_sys = p_sys =
          (filter_sys_t *)malloc(sizeof(filter_sys_t)) ) == NULL )
    {
        msg_Err( p_filter, "out of memory" );
        return VLC_EGENERIC;
    }

    /* Misc init */
    p_filter->pf_video_blend = Blend;

    msg_Dbg( p_filter, "chroma: %4.4s -> %4.4s",
             (char *)&p_filter->fmt_in.video.i_chroma,
             (char *)&p_filter->fmt_out.video.i_chroma );


    return VLC_SUCCESS;
}

/****************************************************************************
 * Blend: the whole thing
 ****************************************************************************
 * This function is called just after the thread is launched.
 ****************************************************************************/
static void Blend( filter_t *p_filter, picture_t *p_dst,
                   picture_t *p_dst_orig, picture_t *p_src,
                   int i_x_offset, int i_y_offset, int i_alpha )
{
    int i_width, i_height;

    i_width = __MIN((int)p_filter->fmt_out.video.i_visible_width - i_x_offset,
                    (int)p_filter->fmt_in.video.i_visible_width);

    i_height = __MIN((int)p_filter->fmt_out.video.i_visible_height -i_y_offset,
                     (int)p_filter->fmt_in.video.i_visible_height);

    if( i_width <= 0 || i_height <= 0 ) return;

    if( p_filter->fmt_in.video.i_chroma == VLC_FOURCC('Y','U','V','A') &&
        ( p_filter->fmt_out.video.i_chroma == VLC_FOURCC('I','4','2','0') ||
          p_filter->fmt_out.video.i_chroma == VLC_FOURCC('Y','V','1','2') ) )
    {
        BlendI420( p_filter, p_dst, p_dst_orig, p_src,
                   i_x_offset, i_y_offset, i_width, i_height, i_alpha );
        return;
    }
    if( p_filter->fmt_in.video.i_chroma == VLC_FOURCC('Y','U','V','A') &&
        p_filter->fmt_out.video.i_chroma == VLC_FOURCC('Y','U','Y','2') )
    {
        BlendYUY2( p_filter, p_dst, p_dst_orig, p_src,
                   i_x_offset, i_y_offset, i_width, i_height, i_alpha );
        return;
    }
    if( p_filter->fmt_in.video.i_chroma == VLC_FOURCC('Y','U','V','A') &&
        p_filter->fmt_out.video.i_chroma == VLC_FOURCC('R','V','1','6') )
    {
        BlendR16( p_filter, p_dst, p_dst_orig, p_src,
                  i_x_offset, i_y_offset, i_width, i_height, i_alpha );
        return;
    }
    if( p_filter->fmt_in.video.i_chroma == VLC_FOURCC('Y','U','V','A') &&
        ( p_filter->fmt_out.video.i_chroma == VLC_FOURCC('R','V','2','4') ||
          p_filter->fmt_out.video.i_chroma == VLC_FOURCC('R','V','3','2') ) )
    {
        BlendR24( p_filter, p_dst, p_dst_orig, p_src,
                  i_x_offset, i_y_offset, i_width, i_height, i_alpha );
        return;
    }
    if( p_filter->fmt_in.video.i_chroma == VLC_FOURCC('Y','U','V','P') &&
        ( p_filter->fmt_out.video.i_chroma == VLC_FOURCC('I','4','2','0') ||
          p_filter->fmt_out.video.i_chroma == VLC_FOURCC('Y','V','1','2') ) )
    {
        BlendPalI420( p_filter, p_dst, p_dst_orig, p_src,
                      i_x_offset, i_y_offset, i_width, i_height, i_alpha );
        return;
    }
    if( p_filter->fmt_in.video.i_chroma == VLC_FOURCC('Y','U','V','P') &&
        p_filter->fmt_out.video.i_chroma == VLC_FOURCC('Y','U','Y','2') )
    {
        BlendPalYUY2( p_filter, p_dst, p_dst_orig, p_src,
                      i_x_offset, i_y_offset, i_width, i_height, i_alpha );
        return;
    }
    if( p_filter->fmt_in.video.i_chroma == VLC_FOURCC('Y','U','V','P') &&
        ( p_filter->fmt_out.video.i_chroma == VLC_FOURCC('R','V','1','6') ||
          p_filter->fmt_out.video.i_chroma == VLC_FOURCC('R','V','2','4') ||
          p_filter->fmt_out.video.i_chroma == VLC_FOURCC('R','V','3','2') ) )
    {
        BlendPalRV( p_filter, p_dst, p_dst_orig, p_src,
                    i_x_offset, i_y_offset, i_width, i_height, i_alpha );
        return;
    }

    msg_Dbg( p_filter, "no matching alpha blending routine" );
}

static void BlendI420( filter_t *p_filter, picture_t *p_dst,
                       picture_t *p_dst_orig, picture_t *p_src,
                       int i_x_offset, int i_y_offset,
                       int i_width, int i_height, int i_alpha )
{
    int i_src1_pitch, i_src2_pitch, i_dst_pitch;
    uint8_t *p_src1_y, *p_src2_y, *p_dst_y;
    uint8_t *p_src1_u, *p_src2_u, *p_dst_u;
    uint8_t *p_src1_v, *p_src2_v, *p_dst_v;
    uint8_t *p_trans;
    int i_x, i_y, i_trans;
    vlc_bool_t b_even_scanline = i_y_offset % 2;

    i_dst_pitch = p_dst->p[Y_PLANE].i_pitch;
    p_dst_y = p_dst->p[Y_PLANE].p_pixels + i_x_offset +
              p_filter->fmt_out.video.i_x_offset +
              p_dst->p[Y_PLANE].i_pitch *
              ( i_y_offset + p_filter->fmt_out.video.i_y_offset );
    p_dst_u = p_dst->p[U_PLANE].p_pixels + i_x_offset/2 +
              p_filter->fmt_out.video.i_x_offset/2 +
              ( i_y_offset + p_filter->fmt_out.video.i_y_offset ) / 2 *
              p_dst->p[U_PLANE].i_pitch;
    p_dst_v = p_dst->p[V_PLANE].p_pixels + i_x_offset/2 +
              p_filter->fmt_out.video.i_x_offset/2 +
              ( i_y_offset + p_filter->fmt_out.video.i_y_offset ) / 2 *
              p_dst->p[V_PLANE].i_pitch;

    i_src1_pitch = p_dst_orig->p[Y_PLANE].i_pitch;
    p_src1_y = p_dst_orig->p[Y_PLANE].p_pixels + i_x_offset +
               p_filter->fmt_out.video.i_x_offset +
               p_dst_orig->p[Y_PLANE].i_pitch *
               ( i_y_offset + p_filter->fmt_out.video.i_y_offset );
    p_src1_u = p_dst_orig->p[U_PLANE].p_pixels + i_x_offset/2 +
               p_filter->fmt_out.video.i_x_offset/2 +
               ( i_y_offset + p_filter->fmt_out.video.i_y_offset ) / 2 *
               p_dst_orig->p[U_PLANE].i_pitch;
    p_src1_v = p_dst_orig->p[V_PLANE].p_pixels + i_x_offset/2 +
               p_filter->fmt_out.video.i_x_offset/2 +
               ( i_y_offset + p_filter->fmt_out.video.i_y_offset ) / 2 *
               p_dst_orig->p[V_PLANE].i_pitch;

    i_src2_pitch = p_src->p[Y_PLANE].i_pitch;
    p_src2_y = p_src->p[Y_PLANE].p_pixels +
               p_filter->fmt_in.video.i_x_offset +
               p_src->p[Y_PLANE].i_pitch * p_filter->fmt_in.video.i_y_offset;
    p_src2_u = p_src->p[U_PLANE].p_pixels +
               p_filter->fmt_in.video.i_x_offset/2 +
               p_src->p[U_PLANE].i_pitch * p_filter->fmt_in.video.i_y_offset/2;
    p_src2_v = p_src->p[V_PLANE].p_pixels +
               p_filter->fmt_in.video.i_x_offset/2 +
               p_src->p[V_PLANE].i_pitch * p_filter->fmt_in.video.i_y_offset/2;

    p_trans = p_src->p[A_PLANE].p_pixels +
              p_filter->fmt_in.video.i_x_offset +
              p_src->p[A_PLANE].i_pitch * p_filter->fmt_in.video.i_y_offset;

#define MAX_TRANS 255
#define TRANS_BITS  8

    /* Draw until we reach the bottom of the subtitle */
    for( i_y = 0; i_y < i_height; i_y++, p_trans += i_src2_pitch,
         p_dst_y += i_dst_pitch, p_src1_y += i_src1_pitch,
         p_src2_y += i_src2_pitch,
         p_dst_u += b_even_scanline ? i_dst_pitch/2 : 0,
         p_src1_u += b_even_scanline ? i_src1_pitch/2 : 0,
         p_src2_u += i_src2_pitch,
         p_dst_v += b_even_scanline ? i_dst_pitch/2 : 0,
         p_src1_v += b_even_scanline ? i_src1_pitch/2 : 0,
         p_src2_v += i_src2_pitch )
    {
        b_even_scanline = !b_even_scanline;

        /* Draw until we reach the end of the line */
        for( i_x = 0; i_x < i_width; i_x++ )
        {
            i_trans = ( p_trans[i_x] * i_alpha ) / 255;
            if( !i_trans )
            {
                /* Completely transparent. Don't change pixel */
                continue;
            }
            else if( i_trans == MAX_TRANS )
            {
                /* Completely opaque. Completely overwrite underlying pixel */
                p_dst_y[i_x] = p_src2_y[i_x];

                if( b_even_scanline && i_x % 2 == 0 )
                {
                    p_dst_u[i_x/2] = p_src2_u[i_x];
                    p_dst_v[i_x/2] = p_src2_v[i_x];
                }
                continue;
            }

            /* Blending */
            p_dst_y[i_x] = ( (uint16_t)p_src2_y[i_x] * i_trans +
                (uint16_t)p_src1_y[i_x] * (MAX_TRANS - i_trans) )
                >> TRANS_BITS;

            if( b_even_scanline && i_x % 2 == 0 )
            {
                p_dst_u[i_x/2] = ( (uint16_t)p_src2_u[i_x] * i_trans +
                (uint16_t)p_src1_u[i_x/2] * (MAX_TRANS - i_trans) )
                >> TRANS_BITS;
                p_dst_v[i_x/2] = ( (uint16_t)p_src2_v[i_x] * i_trans +
                (uint16_t)p_src1_v[i_x/2] * (MAX_TRANS - i_trans) )
                >> TRANS_BITS;
            }
        }