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206 lines
5.9 KiB
C
206 lines
5.9 KiB
C
/* GStreamer
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* Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
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* Library <2002> Ronald Bultje <rbultje@ronald.bitfreak.net>
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* Copyright (C) 2007 David A. Schleef <ds@schleef.org>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <string.h>
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#include <stdio.h>
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#include "video.h"
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#include "gstvideometa.h"
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/**
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* SECTION:gstvideo
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* @title: GstVideo
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* @short_description: Support library for video operations
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*
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* This library contains some helper functions and includes the
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* videosink and videofilter base classes.
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*/
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/**
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* gst_video_calculate_display_ratio:
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* @dar_n: (out): Numerator of the calculated display_ratio
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* @dar_d: (out): Denominator of the calculated display_ratio
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* @video_width: Width of the video frame in pixels
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* @video_height: Height of the video frame in pixels
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* @video_par_n: Numerator of the pixel aspect ratio of the input video.
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* @video_par_d: Denominator of the pixel aspect ratio of the input video.
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* @display_par_n: Numerator of the pixel aspect ratio of the display device
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* @display_par_d: Denominator of the pixel aspect ratio of the display device
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*
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* Given the Pixel Aspect Ratio and size of an input video frame, and the
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* pixel aspect ratio of the intended display device, calculates the actual
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* display ratio the video will be rendered with.
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*
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* Returns: A boolean indicating success and a calculated Display Ratio in the
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* dar_n and dar_d parameters.
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* The return value is FALSE in the case of integer overflow or other error.
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*/
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gboolean
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gst_video_calculate_display_ratio (guint * dar_n, guint * dar_d,
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guint video_width, guint video_height,
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guint video_par_n, guint video_par_d,
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guint display_par_n, guint display_par_d)
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{
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gint num, den;
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gint tmp_n, tmp_d;
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g_return_val_if_fail (dar_n != NULL, FALSE);
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g_return_val_if_fail (dar_d != NULL, FALSE);
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/* Calculate (video_width * video_par_n * display_par_d) /
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* (video_height * video_par_d * display_par_n) */
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if (!gst_util_fraction_multiply (video_width, video_height, video_par_n,
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video_par_d, &tmp_n, &tmp_d))
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goto error_overflow;
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if (!gst_util_fraction_multiply (tmp_n, tmp_d, display_par_d, display_par_n,
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&num, &den))
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goto error_overflow;
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g_return_val_if_fail (num > 0, FALSE);
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g_return_val_if_fail (den > 0, FALSE);
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*dar_n = num;
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*dar_d = den;
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return TRUE;
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/* ERRORS */
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error_overflow:
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{
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GST_WARNING ("overflow in multiply");
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return FALSE;
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}
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}
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/**
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* gst_video_guess_framerate:
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* @duration: Nominal duration of one frame
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* @dest_n: (out) (allow-none): Numerator of the calculated framerate
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* @dest_d: (out) (allow-none): Denominator of the calculated framerate
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*
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* Given the nominal duration of one video frame,
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* this function will check some standard framerates for
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* a close match (within 0.1%) and return one if possible,
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*
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* It will calculate an arbitrary framerate if no close
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* match was found, and return %FALSE.
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*
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* It returns %FALSE if a duration of 0 is passed.
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*
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* Returns: %TRUE if a close "standard" framerate was
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* recognised, and %FALSE otherwise.
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*
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* Since: 1.6
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*/
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gboolean
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gst_video_guess_framerate (GstClockTime duration, gint * dest_n, gint * dest_d)
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{
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const int common_den[] = { 1, 2, 3, 4, 1001 };
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int best_n, best_d, gcd;
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guint64 best_error = G_MAXUINT64;
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guint64 a;
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int i;
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if (G_UNLIKELY (duration == 0))
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return FALSE;
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/* Use a limited precision conversion by default for more sensible results,
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* unless the frame duration is absurdly small (high speed cameras?) */
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if (duration > 100000) {
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best_n = GST_SECOND / 10000;
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best_d = duration / 10000;
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} else {
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best_n = GST_SECOND;
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best_d = duration;
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}
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for (i = 0; i < G_N_ELEMENTS (common_den); i++) {
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gint d = common_den[i];
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gint n = gst_util_uint64_scale_round (d, GST_SECOND, duration);
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/* For NTSC framerates, round to the nearest 1000 fps */
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if (d == 1001) {
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n += 500;
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n -= (n % 1000);
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}
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if (n > 0) {
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/* See what duration the given framerate should be */
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a = gst_util_uint64_scale_int (GST_SECOND, d, n);
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/* Compute absolute error */
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a = (a < duration) ? (duration - a) : (a - duration);
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if (a < 2) {
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/* Really precise - take this option */
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if (dest_n)
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*dest_n = n;
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if (dest_d)
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*dest_d = d;
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return TRUE;
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}
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/* If within 0.1%, remember this denominator */
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if (a * 1000 < duration && a < best_error) {
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best_error = a;
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best_n = n;
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best_d = d;
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}
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}
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}
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/* set results */
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gcd = gst_util_greatest_common_divisor (best_n, best_d);
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if (gcd) {
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best_n /= gcd;
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best_d /= gcd;
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}
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if (dest_n)
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*dest_n = best_n;
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if (dest_d)
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*dest_d = best_d;
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return (best_error != G_MAXUINT64);
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}
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/**
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* gst_video_alignment_reset:
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* @align: a #GstVideoAlignment
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*
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* Set @align to its default values with no padding and no alignment.
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*/
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void
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gst_video_alignment_reset (GstVideoAlignment * align)
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{
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gint i;
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g_return_if_fail (align != NULL);
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align->padding_top = 0;
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align->padding_bottom = 0;
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align->padding_left = 0;
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align->padding_right = 0;
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for (i = 0; i < GST_VIDEO_MAX_PLANES; i++)
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align->stride_align[i] = 0;
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}
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