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timecode.c
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timecode.c
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/*
* Copyright (c) 2006 Smartjog S.A.S, Baptiste Coudurier <baptiste.coudurier@gmail.com>
* Copyright (c) 2011-2012 Smartjog S.A.S, Clément Bœsch <clement.boesch@smartjog.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* Timecode helpers
* @see https://en.wikipedia.org/wiki/SMPTE_time_code
* @see http://www.dropframetimecode.org
*/
#include <stdio.h>
#include "timecode.h"
#include "log.h"
#include "error.h"
int av_timecode_adjust_ntsc_framenum(int framenum)
{
/* only works for NTSC 29.97 */
int d = framenum / 17982;
int m = framenum % 17982;
//if (m < 2) m += 2; /* not needed since -2,-1 / 1798 in C returns 0 */
return framenum + 18 * d + 2 * ((m - 2) / 1798);
}
uint32_t av_timecode_get_smpte_from_framenum(const AVTimecode *tc, int framenum)
{
unsigned fps = tc->fps;
int drop = !!(tc->flags & AV_TIMECODE_FLAG_DROPFRAME);
int hh, mm, ss, ff;
framenum += tc->start;
if (drop)
framenum = av_timecode_adjust_ntsc_framenum(framenum);
ff = framenum % fps;
ss = framenum / fps % 60;
mm = framenum / (fps*60) % 60;
hh = framenum / (fps*3600) % 24;
return 0 << 31 | // color frame flag (0: unsync mode, 1: sync mode)
drop << 30 | // drop frame flag (0: non drop, 1: drop)
(ff / 10) << 28 | // tens of frames
(ff % 10) << 24 | // units of frames
0 << 23 | // PC (NTSC) or BGF0 (PAL)
(ss / 10) << 20 | // tens of seconds
(ss % 10) << 16 | // units of seconds
0 << 15 | // BGF0 (NTSC) or BGF2 (PAL)
(mm / 10) << 12 | // tens of minutes
(mm % 10) << 8 | // units of minutes
0 << 7 | // BGF2 (NTSC) or PC (PAL)
0 << 6 | // BGF1
(hh / 10) << 4 | // tens of hours
(hh % 10); // units of hours
}
char *av_timecode_make_string(const AVTimecode *tc, char *buf, int framenum)
{
int fps = tc->fps;
int drop = tc->flags & AV_TIMECODE_FLAG_DROPFRAME;
int hh, mm, ss, ff, neg = 0;
framenum += tc->start;
if (drop)
framenum = av_timecode_adjust_ntsc_framenum(framenum);
if (framenum < 0) {
framenum = -framenum;
neg = tc->flags & AV_TIMECODE_FLAG_ALLOWNEGATIVE;
}
ff = framenum % fps;
ss = framenum / fps % 60;
mm = framenum / (fps*60) % 60;
hh = framenum / (fps*3600);
if (tc->flags & AV_TIMECODE_FLAG_24HOURSMAX)
hh = hh % 24;
snprintf(buf, AV_TIMECODE_STR_SIZE, "%s%02d:%02d:%02d%c%02d",
neg ? "-" : "",
hh, mm, ss, drop ? ';' : ':', ff);
return buf;
}
static unsigned bcd2uint(uint8_t bcd)
{
unsigned low = bcd & 0xf;
unsigned high = bcd >> 4;
if (low > 9 || high > 9)
return 0;
return low + 10*high;
}
char *av_timecode_make_smpte_tc_string(char *buf, uint32_t tcsmpte, int prevent_df)
{
unsigned hh = bcd2uint(tcsmpte & 0x3f); // 6-bit hours
unsigned mm = bcd2uint(tcsmpte>>8 & 0x7f); // 7-bit minutes
unsigned ss = bcd2uint(tcsmpte>>16 & 0x7f); // 7-bit seconds
unsigned ff = bcd2uint(tcsmpte>>24 & 0x3f); // 6-bit frames
unsigned drop = tcsmpte & 1<<30 && !prevent_df; // 1-bit drop if not arbitrary bit
snprintf(buf, AV_TIMECODE_STR_SIZE, "%02u:%02u:%02u%c%02u",
hh, mm, ss, drop ? ';' : ':', ff);
return buf;
}
char *av_timecode_make_mpeg_tc_string(char *buf, uint32_t tc25bit)
{
snprintf(buf, AV_TIMECODE_STR_SIZE, "%02u:%02u:%02u%c%02u",
tc25bit>>19 & 0x1f, // 5-bit hours
tc25bit>>13 & 0x3f, // 6-bit minutes
tc25bit>>6 & 0x3f, // 6-bit seconds
tc25bit & 1<<24 ? ';' : ':', // 1-bit drop flag
tc25bit & 0x3f); // 6-bit frames
return buf;
}
static int check_timecode(void *log_ctx, AVTimecode *tc)
{
if (tc->fps <= 0) {
av_log(log_ctx, AV_LOG_ERROR, "Timecode frame rate must be specified\n");
return AVERROR(EINVAL);
}
if ((tc->flags & AV_TIMECODE_FLAG_DROPFRAME) && tc->fps != 30) {
av_log(log_ctx, AV_LOG_ERROR, "Drop frame is only allowed with 30000/1001 FPS\n");
return AVERROR(EINVAL);
}
switch (tc->fps) {
case 24:
case 25:
case 30: return 0;
default:
av_log(log_ctx, AV_LOG_ERROR, "Timecode frame rate not supported\n");
return AVERROR_PATCHWELCOME;
}
}
static int fps_from_frame_rate(AVRational rate)
{
if (!rate.den || !rate.num)
return -1;
return (rate.num + rate.den/2) / rate.den;
}
int av_timecode_init(AVTimecode *tc, AVRational rate, int flags, int frame_start, void *log_ctx)
{
memset(tc, 0, sizeof(*tc));
tc->start = frame_start;
tc->flags = flags;
tc->rate = rate;
tc->fps = fps_from_frame_rate(rate);
return check_timecode(log_ctx, tc);
}
int av_timecode_init_from_string(AVTimecode *tc, AVRational rate, const char *str, void *log_ctx)
{
char c;
int hh, mm, ss, ff, ret;
if (sscanf(str, "%d:%d:%d%c%d", &hh, &mm, &ss, &c, &ff) != 5) {
av_log(log_ctx, AV_LOG_ERROR, "Unable to parse timecode, "
"syntax: hh:mm:ss[:;.]ff\n");
return AVERROR_INVALIDDATA;
}
memset(tc, 0, sizeof(*tc));
tc->flags = c != ':' ? AV_TIMECODE_FLAG_DROPFRAME : 0; // drop if ';', '.', ...
tc->rate = rate;
tc->fps = fps_from_frame_rate(rate);
ret = check_timecode(log_ctx, tc);
if (ret < 0)
return ret;
tc->start = (hh*3600 + mm*60 + ss) * tc->fps + ff;
if (tc->flags & AV_TIMECODE_FLAG_DROPFRAME) { /* adjust frame number */
int tmins = 60*hh + mm;
tc->start -= 2 * (tmins - tmins/10);
}
return 0;
}