gstreamer/gst-libs/gst/video/video.c
2012-07-13 12:11:06 +02:00

99 lines
3.2 KiB
C

/* GStreamer
* Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
* Library <2002> Ronald Bultje <rbultje@ronald.bitfreak.net>
* Copyright (C) 2007 David A. Schleef <ds@schleef.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <string.h>
#include <stdio.h>
#include "video.h"
#include "gstvideometa.h"
/**
* SECTION:gstvideo
* @short_description: Support library for video operations
*
* <refsect2>
* <para>
* This library contains some helper functions and includes the
* videosink and videofilter base classes.
* </para>
* </refsect2>
*/
/**
* gst_video_calculate_display_ratio:
* @dar_n: Numerator of the calculated display_ratio
* @dar_d: Denominator of the calculated display_ratio
* @video_width: Width of the video frame in pixels
* @video_height: Height of the video frame in pixels
* @video_par_n: Numerator of the pixel aspect ratio of the input video.
* @video_par_d: Denominator of the pixel aspect ratio of the input video.
* @display_par_n: Numerator of the pixel aspect ratio of the display device
* @display_par_d: Denominator of the pixel aspect ratio of the display device
*
* Given the Pixel Aspect Ratio and size of an input video frame, and the
* pixel aspect ratio of the intended display device, calculates the actual
* display ratio the video will be rendered with.
*
* Returns: A boolean indicating success and a calculated Display Ratio in the
* dar_n and dar_d parameters.
* The return value is FALSE in the case of integer overflow or other error.
*/
gboolean
gst_video_calculate_display_ratio (guint * dar_n, guint * dar_d,
guint video_width, guint video_height,
guint video_par_n, guint video_par_d,
guint display_par_n, guint display_par_d)
{
gint num, den;
gint tmp_n, tmp_d;
g_return_val_if_fail (dar_n != NULL, FALSE);
g_return_val_if_fail (dar_d != NULL, FALSE);
/* Calculate (video_width * video_par_n * display_par_d) /
* (video_height * video_par_d * display_par_n) */
if (!gst_util_fraction_multiply (video_width, video_height, video_par_n,
video_par_d, &tmp_n, &tmp_d))
goto error_overflow;
if (!gst_util_fraction_multiply (tmp_n, tmp_d, display_par_d, display_par_n,
&num, &den))
goto error_overflow;
g_return_val_if_fail (num > 0, FALSE);
g_return_val_if_fail (den > 0, FALSE);
*dar_n = num;
*dar_d = den;
return TRUE;
/* ERRORS */
error_overflow:
{
GST_WARNING ("overflow in multiply");
return FALSE;
}
}