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/*
Copyright (C) 2012 Carl Hetherington <cth@carlh.net>
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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "subtitle.h"
#include "image.h"
#include "exceptions.h"
#include "film_state.h"
using namespace std;
using namespace boost;
Subtitle::Subtitle (AVSubtitle const & sub)
{
/* subtitle PTS in seconds */
float const packet_time = (sub.pts / AV_TIME_BASE) + float (sub.pts % AV_TIME_BASE) / 1e6;
/* hence start time for this sub */
_from = packet_time + (double (sub.start_display_time) / 1e3);
_to = packet_time + (double (sub.end_display_time) / 1e3);
for (unsigned int i = 0; i < sub.num_rects; ++i) {
_images.push_back (shared_ptr<SubtitleImage> (new SubtitleImage (sub.rects[i])));
}
}
/** @param t Time in seconds from the start of the film */
bool
Subtitle::displayed_at (double t)
{
return t >= _from && t <= _to;
}
SubtitleImage::SubtitleImage (AVSubtitleRect const * rect)
: _position (rect->x, rect->y)
, _image (new SimpleImage (PIX_FMT_RGBA, Size (rect->w, rect->h)))
{
if (rect->type != SUBTITLE_BITMAP) {
throw DecodeError ("non-bitmap subtitles not yet supported");
}
/* Start of the first line in the subtitle */
uint8_t* sub_p = rect->pict.data[0];
/* sub_p looks up into a RGB palette which is here */
uint32_t const * palette = (uint32_t *) rect->pict.data[1];
/* Start of the output data */
uint32_t* out_p = (uint32_t *) _image->data()[0];
for (int y = 0; y < rect->h; ++y) {
uint8_t* sub_line_p = sub_p;
for (int x = 0; x < rect->w; ++x) {
*out_p++ = palette[*sub_line_p++];
}
sub_p += rect->pict.linesize[0];
}
}
SubtitleTransform
subtitle_transform (
int target_base_width, int target_base_height,
float target_x_scale, float target_y_scale,
Position sub_pos, int sub_width, int sub_height,
shared_ptr<FilmState> fs
)
{
SubtitleTransform tx;
/* The area of the original subtitle, in the coordinate space of the source video frame */
Rectangle sub_area (sub_pos.x, sub_pos.y + fs->subtitle_offset, sub_width, sub_height);
/* The cropped area of the source video frame, in the same coordinate space */
Rectangle cropped_target_area (
fs->crop.left,
fs->crop.top,
target_base_width - (fs->crop.left + fs->crop.right),
target_base_height - (fs->crop.top + fs->crop.bottom)
);
/* Hence the area of the cropped subtitle, in the same coordinate space */
Rectangle cropped_sub_area = sub_area.intersection (cropped_target_area);
/* The crop that should be applied to the subtitle, in its coordinate space */
tx.crop.x = cropped_sub_area.x - sub_area.x;
tx.crop.y = cropped_sub_area.y - sub_area.y;
tx.crop.w = cropped_sub_area.w;
tx.crop.h = cropped_sub_area.h;
/* We will scale the subtitle by the same amount as the video frame, and also by the additional
subtitle_scale
*/
tx.transformed.w = cropped_sub_area.w * target_x_scale * fs->subtitle_scale;
tx.transformed.h = cropped_sub_area.h * target_y_scale * fs->subtitle_scale;
/* Then we need a corrective translation, consisting of two parts:
*
* 1. that which is the result of the scaling of the subtitle by target_x_scale and target_y_scale; this will be
* (sub_area.x - fs->crop_left) * target_x_scale and (sub_area.y - fs->crop_top) * target_y_scale.
*
* 2. that to shift the origin of the scale by fs->subtitle_scale to the centre of the subtitle; this will be
* (width_before_subtitle_scale * (1 - fs->subtitle_scale) / 2) and
* (height_before_subtitle_scale * (1 - fs->subtitle_scale) / 2).
*
* Combining these two translations gives these expressions.
*/
tx.transformed.x = target_x_scale * ((sub_area.x - fs->crop.left) + (cropped_sub_area.w * (1 - fs->subtitle_scale) / 2));
tx.transformed.y = target_y_scale * ((sub_area.y - fs->crop.top) + (cropped_sub_area.h * (1 - fs->subtitle_scale) / 2));
return tx;
}
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