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29173242bb
Code to convert time codes to/from timestamps and frame numbers.
240 lines
6.8 KiB
C
240 lines
6.8 KiB
C
/* GStreamer
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* Copyright (C) 2009 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., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/*
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* Utility functions for handing SMPTE Time Codes, as described in
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* SMPTE Standard 12M-1999.
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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 "gstsmptetimecode.h"
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#define NTSC_FRAMES_PER_10_MINS (10*60*30 - 10*2 + 2)
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#define NTSC_FRAMES_PER_HOUR (6*NTSC_FRAMES_PER_10_MINS)
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/**
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* gst_smpte_time_code_from_frame_number:
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* @system: SMPTE Time Code system
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* @time_code: pointer to time code structure
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* @frame_number: integer frame number
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*
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* Converts a frame number to a time code.
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*
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* Returns: TRUE if the conversion was successful
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*/
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gboolean
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gst_smpte_time_code_from_frame_number (GstSMPTETimeCodeSystem system,
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GstSMPTETimeCode * time_code, int frame_number)
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{
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int ten_mins;
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int n;
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g_return_val_if_fail (time_code != NULL, FALSE);
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g_return_val_if_fail (GST_SMPTE_TIME_CODE_SYSTEM_IS_VALID (system), FALSE);
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time_code->hours = 99;
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time_code->minutes = 99;
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time_code->seconds = 99;
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time_code->frames = 99;
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if (frame_number < 0)
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return FALSE;
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switch (system) {
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case GST_SMPTE_TIME_CODE_SYSTEM_30:
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if (frame_number >= 24 * NTSC_FRAMES_PER_HOUR)
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return FALSE;
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ten_mins = frame_number / NTSC_FRAMES_PER_10_MINS;
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frame_number -= ten_mins * NTSC_FRAMES_PER_10_MINS;
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time_code->hours = ten_mins / 6;
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time_code->minutes = 10 * (ten_mins % 6);
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if (frame_number < 2) {
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/* treat the first two frames of each ten minutes specially */
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time_code->seconds = 0;
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time_code->frames = frame_number;
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} else {
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n = (frame_number - 2) / (60 * 30 - 2);
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time_code->minutes += n;
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frame_number -= n * (60 * 30 - 2);
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time_code->seconds = frame_number / 30;
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time_code->frames = frame_number % 30;
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}
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break;
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case GST_SMPTE_TIME_CODE_SYSTEM_25:
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if (frame_number >= 24 * 60 * 60 * 25)
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return FALSE;
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time_code->frames = frame_number % 25;
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frame_number /= 25;
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time_code->seconds = frame_number % 60;
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frame_number /= 60;
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time_code->minutes = frame_number % 60;
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frame_number /= 60;
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time_code->hours = frame_number;
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break;
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case GST_SMPTE_TIME_CODE_SYSTEM_24:
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if (frame_number >= 24 * 60 * 60 * 24)
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return FALSE;
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time_code->frames = frame_number % 24;
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frame_number /= 24;
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time_code->seconds = frame_number % 60;
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frame_number /= 60;
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time_code->minutes = frame_number % 60;
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frame_number /= 60;
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time_code->hours = frame_number;
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break;
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}
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return TRUE;
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}
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/**
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* gst_smpte_time_code_is_valid:
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* @system: SMPTE Time Code system
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* @time_code: pointer to time code structure
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*
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* Checks that the time code represents a valid time code.
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*
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* Returns: TRUE if the time code is valid
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*/
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gboolean
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gst_smpte_time_code_is_valid (GstSMPTETimeCodeSystem system,
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GstSMPTETimeCode * time_code)
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{
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g_return_val_if_fail (time_code != NULL, FALSE);
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g_return_val_if_fail (GST_SMPTE_TIME_CODE_SYSTEM_IS_VALID (system), FALSE);
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if (time_code->hours < 0 || time_code->hours >= 24)
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return FALSE;
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if (time_code->minutes < 0 || time_code->minutes >= 60)
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return FALSE;
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if (time_code->seconds < 0 || time_code->seconds >= 60)
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return FALSE;
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if (time_code->frames < 0)
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return FALSE;
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switch (system) {
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case GST_SMPTE_TIME_CODE_SYSTEM_30:
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if (time_code->frames >= 30)
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return FALSE;
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if (time_code->frames >= 2 || time_code->seconds > 0)
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return TRUE;
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if (time_code->minutes % 10 != 0)
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return FALSE;
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break;
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case GST_SMPTE_TIME_CODE_SYSTEM_25:
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if (time_code->frames >= 25)
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return FALSE;
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break;
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case GST_SMPTE_TIME_CODE_SYSTEM_24:
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if (time_code->frames >= 24)
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return FALSE;
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break;
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}
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return TRUE;
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}
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/**
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* gst_smpte_time_get_frame_number:
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* @system: SMPTE Time Code system
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* @frame_number: pointer to frame number
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* @time_code: pointer to time code structure
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*
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* Converts the time code structure to a linear frame number.
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*
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* Returns: TRUE if the time code could be converted
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*/
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gboolean
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gst_smpte_time_code_get_frame_number (GstSMPTETimeCodeSystem system,
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int *frame_number, GstSMPTETimeCode * time_code)
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{
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int frame = 0;
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g_return_val_if_fail (GST_SMPTE_TIME_CODE_SYSTEM_IS_VALID (system), FALSE);
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g_return_val_if_fail (time_code != NULL, FALSE);
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if (!gst_smpte_time_code_is_valid (system, time_code)) {
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return FALSE;
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}
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switch (system) {
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case GST_SMPTE_TIME_CODE_SYSTEM_30:
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frame = time_code->hours * NTSC_FRAMES_PER_HOUR;
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frame += (time_code->minutes / 10) * NTSC_FRAMES_PER_10_MINS;
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frame += (time_code->minutes % 10) * (30 * 60 - 2);
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frame += time_code->seconds * 30;
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break;
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case GST_SMPTE_TIME_CODE_SYSTEM_25:
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time_code->frames =
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25 * ((time_code->hours * 60 + time_code->minutes) * 60 +
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time_code->seconds);
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break;
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case GST_SMPTE_TIME_CODE_SYSTEM_24:
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time_code->frames =
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24 * ((time_code->hours * 60 + time_code->minutes) * 60 +
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time_code->seconds);
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break;
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}
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frame += time_code->frames;
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if (frame_number) {
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*frame_number = frame;
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}
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return TRUE;
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}
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/**
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* gst_smpte_time_get_timestamp:
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* @system: SMPTE Time Code system
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* @time_code: pointer to time code structure
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*
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* Converts the time code structure to a timestamp.
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*
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* Returns: Time stamp for time code, or GST_CLOCK_TIME_NONE if time
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* code is invalid.
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*/
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GstClockTime
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gst_smpte_time_code_get_timestamp (GstSMPTETimeCodeSystem system,
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GstSMPTETimeCode * time_code)
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{
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int frame_number;
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g_return_val_if_fail (GST_SMPTE_TIME_CODE_SYSTEM_IS_VALID (system),
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GST_CLOCK_TIME_NONE);
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g_return_val_if_fail (time_code != NULL, GST_CLOCK_TIME_NONE);
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if (gst_smpte_time_code_get_frame_number (system, &frame_number, time_code)) {
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static int framerate_n[3] = { 3000, 25, 24 };
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static int framerate_d[3] = { 1001, 1, 1 };
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return gst_util_uint64_scale (frame_number,
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GST_SECOND * framerate_d[system], framerate_n[system]);
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}
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return GST_CLOCK_TIME_NONE;
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}
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