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timecode.c
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1 /*
2  * Copyright (c) 2006 Smartjog S.A.S, Baptiste Coudurier <baptiste.coudurier@gmail.com>
3  * Copyright (c) 2011-2012 Smartjog S.A.S, Clément Bœsch <clement.boesch@smartjog.com>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * Timecode helpers
25  * @see https://en.wikipedia.org/wiki/SMPTE_time_code
26  * @see http://www.dropframetimecode.org
27  */
28 
29 #include <stdio.h>
30 #include "timecode.h"
31 #include "log.h"
32 #include "error.h"
33 
34 int av_timecode_adjust_ntsc_framenum2(int framenum, int fps)
35 {
36  /* only works for NTSC 29.97 and 59.94 */
37  int drop_frames = 0;
38  int d = framenum / 17982;
39  int m = framenum % 17982;
40 
41  if (fps == 30)
42  drop_frames = 2;
43  else if (fps == 60)
44  drop_frames = 4;
45  else
46  return framenum;
47 
48  //if (m < 2) m += 2; /* not needed since -2,-1 / 1798 in C returns 0 */
49  return framenum + 9 * drop_frames * d + drop_frames * ((m - 2) / 1798);
50 }
51 
52 uint32_t av_timecode_get_smpte_from_framenum(const AVTimecode *tc, int framenum)
53 {
54  unsigned fps = tc->fps;
55  int drop = !!(tc->flags & AV_TIMECODE_FLAG_DROPFRAME);
56  int hh, mm, ss, ff;
57 
58  framenum += tc->start;
59  if (drop)
60  framenum = av_timecode_adjust_ntsc_framenum2(framenum, tc->fps);
61  ff = framenum % fps;
62  ss = framenum / fps % 60;
63  mm = framenum / (fps*60) % 60;
64  hh = framenum / (fps*3600) % 24;
65  return 0 << 31 | // color frame flag (0: unsync mode, 1: sync mode)
66  drop << 30 | // drop frame flag (0: non drop, 1: drop)
67  (ff / 10) << 28 | // tens of frames
68  (ff % 10) << 24 | // units of frames
69  0 << 23 | // PC (NTSC) or BGF0 (PAL)
70  (ss / 10) << 20 | // tens of seconds
71  (ss % 10) << 16 | // units of seconds
72  0 << 15 | // BGF0 (NTSC) or BGF2 (PAL)
73  (mm / 10) << 12 | // tens of minutes
74  (mm % 10) << 8 | // units of minutes
75  0 << 7 | // BGF2 (NTSC) or PC (PAL)
76  0 << 6 | // BGF1
77  (hh / 10) << 4 | // tens of hours
78  (hh % 10); // units of hours
79 }
80 
81 char *av_timecode_make_string(const AVTimecode *tc, char *buf, int framenum)
82 {
83  int fps = tc->fps;
84  int drop = tc->flags & AV_TIMECODE_FLAG_DROPFRAME;
85  int hh, mm, ss, ff, neg = 0;
86 
87  framenum += tc->start;
88  if (drop)
89  framenum = av_timecode_adjust_ntsc_framenum2(framenum, fps);
90  if (framenum < 0) {
91  framenum = -framenum;
92  neg = tc->flags & AV_TIMECODE_FLAG_ALLOWNEGATIVE;
93  }
94  ff = framenum % fps;
95  ss = framenum / fps % 60;
96  mm = framenum / (fps*60) % 60;
97  hh = framenum / (fps*3600);
98  if (tc->flags & AV_TIMECODE_FLAG_24HOURSMAX)
99  hh = hh % 24;
100  snprintf(buf, AV_TIMECODE_STR_SIZE, "%s%02d:%02d:%02d%c%02d",
101  neg ? "-" : "",
102  hh, mm, ss, drop ? ';' : ':', ff);
103  return buf;
104 }
105 
106 static unsigned bcd2uint(uint8_t bcd)
107 {
108  unsigned low = bcd & 0xf;
109  unsigned high = bcd >> 4;
110  if (low > 9 || high > 9)
111  return 0;
112  return low + 10*high;
113 }
114 
115 char *av_timecode_make_smpte_tc_string(char *buf, uint32_t tcsmpte, int prevent_df)
116 {
117  unsigned hh = bcd2uint(tcsmpte & 0x3f); // 6-bit hours
118  unsigned mm = bcd2uint(tcsmpte>>8 & 0x7f); // 7-bit minutes
119  unsigned ss = bcd2uint(tcsmpte>>16 & 0x7f); // 7-bit seconds
120  unsigned ff = bcd2uint(tcsmpte>>24 & 0x3f); // 6-bit frames
121  unsigned drop = tcsmpte & 1<<30 && !prevent_df; // 1-bit drop if not arbitrary bit
122  snprintf(buf, AV_TIMECODE_STR_SIZE, "%02u:%02u:%02u%c%02u",
123  hh, mm, ss, drop ? ';' : ':', ff);
124  return buf;
125 }
126 
127 char *av_timecode_make_mpeg_tc_string(char *buf, uint32_t tc25bit)
128 {
129  snprintf(buf, AV_TIMECODE_STR_SIZE, "%02u:%02u:%02u%c%02u",
130  tc25bit>>19 & 0x1f, // 5-bit hours
131  tc25bit>>13 & 0x3f, // 6-bit minutes
132  tc25bit>>6 & 0x3f, // 6-bit seconds
133  tc25bit & 1<<24 ? ';' : ':', // 1-bit drop flag
134  tc25bit & 0x3f); // 6-bit frames
135  return buf;
136 }
137 
138 static int check_fps(int fps)
139 {
140  int i;
141  static const int supported_fps[] = {24, 25, 30, 50, 60};
142 
143  for (i = 0; i < FF_ARRAY_ELEMS(supported_fps); i++)
144  if (fps == supported_fps[i])
145  return 0;
146  return -1;
147 }
148 
149 static int check_timecode(void *log_ctx, AVTimecode *tc)
150 {
151  if (tc->fps <= 0) {
152  av_log(log_ctx, AV_LOG_ERROR, "Timecode frame rate must be specified\n");
153  return AVERROR(EINVAL);
154  }
155  if ((tc->flags & AV_TIMECODE_FLAG_DROPFRAME) && tc->fps != 30) {
156  av_log(log_ctx, AV_LOG_ERROR, "Drop frame is only allowed with 30000/1001 FPS\n");
157  return AVERROR(EINVAL);
158  }
159  if (check_fps(tc->fps) < 0) {
160  av_log(log_ctx, AV_LOG_ERROR, "Timecode frame rate %d/%d not supported\n",
161  tc->rate.num, tc->rate.den);
162  return AVERROR_PATCHWELCOME;
163  }
164  return 0;
165 }
166 
167 static int fps_from_frame_rate(AVRational rate)
168 {
169  if (!rate.den || !rate.num)
170  return -1;
171  return (rate.num + rate.den/2) / rate.den;
172 }
173 
174 int av_timecode_check_frame_rate(AVRational rate)
175 {
176  return check_fps(fps_from_frame_rate(rate));
177 }
178 
179 int av_timecode_init(AVTimecode *tc, AVRational rate, int flags, int frame_start, void *log_ctx)
180 {
181  memset(tc, 0, sizeof(*tc));
182  tc->start = frame_start;
183  tc->flags = flags;
184  tc->rate = rate;
185  tc->fps = fps_from_frame_rate(rate);
186  return check_timecode(log_ctx, tc);
187 }
188 
189 int av_timecode_init_from_string(AVTimecode *tc, AVRational rate, const char *str, void *log_ctx)
190 {
191  char c;
192  int hh, mm, ss, ff, ret;
193 
194  if (sscanf(str, "%d:%d:%d%c%d", &hh, &mm, &ss, &c, &ff) != 5) {
195  av_log(log_ctx, AV_LOG_ERROR, "Unable to parse timecode, "
196  "syntax: hh:mm:ss[:;.]ff\n");
197  return AVERROR_INVALIDDATA;
198  }
199 
200  memset(tc, 0, sizeof(*tc));
201  tc->flags = c != ':' ? AV_TIMECODE_FLAG_DROPFRAME : 0; // drop if ';', '.', ...
202  tc->rate = rate;
203  tc->fps = fps_from_frame_rate(rate);
204 
205  ret = check_timecode(log_ctx, tc);
206  if (ret < 0)
207  return ret;
208 
209  tc->start = (hh*3600 + mm*60 + ss) * tc->fps + ff;
210  if (tc->flags & AV_TIMECODE_FLAG_DROPFRAME) { /* adjust frame number */
211  int tmins = 60*hh + mm;
212  tc->start -= 2 * (tmins - tmins/10);
213  }
214  return 0;
215 }
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