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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, m, frames_per_10mins;
39 
40  if (fps == 30) {
41  drop_frames = 2;
42  frames_per_10mins = 17982;
43  } else if (fps == 60) {
44  drop_frames = 4;
45  frames_per_10mins = 35964;
46  } else
47  return framenum;
48 
49  d = framenum / frames_per_10mins;
50  m = framenum % frames_per_10mins;
51 
52  return framenum + 9 * drop_frames * d + drop_frames * ((m - drop_frames) / (frames_per_10mins / 10));
53 }
54 
55 uint32_t av_timecode_get_smpte_from_framenum(const AVTimecode *tc, int framenum)
56 {
57  unsigned fps = tc->fps;
58  int drop = !!(tc->flags & AV_TIMECODE_FLAG_DROPFRAME);
59  int hh, mm, ss, ff;
60 
61  framenum += tc->start;
62  if (drop)
63  framenum = av_timecode_adjust_ntsc_framenum2(framenum, tc->fps);
64  ff = framenum % fps;
65  ss = framenum / fps % 60;
66  mm = framenum / (fps*60) % 60;
67  hh = framenum / (fps*3600) % 24;
68  return 0 << 31 | // color frame flag (0: unsync mode, 1: sync mode)
69  drop << 30 | // drop frame flag (0: non drop, 1: drop)
70  (ff / 10) << 28 | // tens of frames
71  (ff % 10) << 24 | // units of frames
72  0 << 23 | // PC (NTSC) or BGF0 (PAL)
73  (ss / 10) << 20 | // tens of seconds
74  (ss % 10) << 16 | // units of seconds
75  0 << 15 | // BGF0 (NTSC) or BGF2 (PAL)
76  (mm / 10) << 12 | // tens of minutes
77  (mm % 10) << 8 | // units of minutes
78  0 << 7 | // BGF2 (NTSC) or PC (PAL)
79  0 << 6 | // BGF1
80  (hh / 10) << 4 | // tens of hours
81  (hh % 10); // units of hours
82 }
83 
84 char *av_timecode_make_string(const AVTimecode *tc, char *buf, int framenum)
85 {
86  int fps = tc->fps;
87  int drop = tc->flags & AV_TIMECODE_FLAG_DROPFRAME;
88  int hh, mm, ss, ff, neg = 0;
89 
90  framenum += tc->start;
91  if (drop)
92  framenum = av_timecode_adjust_ntsc_framenum2(framenum, fps);
93  if (framenum < 0) {
94  framenum = -framenum;
95  neg = tc->flags & AV_TIMECODE_FLAG_ALLOWNEGATIVE;
96  }
97  ff = framenum % fps;
98  ss = framenum / fps % 60;
99  mm = framenum / (fps*60) % 60;
100  hh = framenum / (fps*3600);
101  if (tc->flags & AV_TIMECODE_FLAG_24HOURSMAX)
102  hh = hh % 24;
103  snprintf(buf, AV_TIMECODE_STR_SIZE, "%s%02d:%02d:%02d%c%02d",
104  neg ? "-" : "",
105  hh, mm, ss, drop ? ';' : ':', ff);
106  return buf;
107 }
108 
109 static unsigned bcd2uint(uint8_t bcd)
110 {
111  unsigned low = bcd & 0xf;
112  unsigned high = bcd >> 4;
113  if (low > 9 || high > 9)
114  return 0;
115  return low + 10*high;
116 }
117 
118 char *av_timecode_make_smpte_tc_string(char *buf, uint32_t tcsmpte, int prevent_df)
119 {
120  unsigned hh = bcd2uint(tcsmpte & 0x3f); // 6-bit hours
121  unsigned mm = bcd2uint(tcsmpte>>8 & 0x7f); // 7-bit minutes
122  unsigned ss = bcd2uint(tcsmpte>>16 & 0x7f); // 7-bit seconds
123  unsigned ff = bcd2uint(tcsmpte>>24 & 0x3f); // 6-bit frames
124  unsigned drop = tcsmpte & 1<<30 && !prevent_df; // 1-bit drop if not arbitrary bit
125  snprintf(buf, AV_TIMECODE_STR_SIZE, "%02u:%02u:%02u%c%02u",
126  hh, mm, ss, drop ? ';' : ':', ff);
127  return buf;
128 }
129 
130 char *av_timecode_make_mpeg_tc_string(char *buf, uint32_t tc25bit)
131 {
132  snprintf(buf, AV_TIMECODE_STR_SIZE, "%02u:%02u:%02u%c%02u",
133  tc25bit>>19 & 0x1f, // 5-bit hours
134  tc25bit>>13 & 0x3f, // 6-bit minutes
135  tc25bit>>6 & 0x3f, // 6-bit seconds
136  tc25bit & 1<<24 ? ';' : ':', // 1-bit drop flag
137  tc25bit & 0x3f); // 6-bit frames
138  return buf;
139 }
140 
141 static int check_fps(int fps)
142 {
143  int i;
144  static const int supported_fps[] = {24, 25, 30, 50, 60};
145 
146  for (i = 0; i < FF_ARRAY_ELEMS(supported_fps); i++)
147  if (fps == supported_fps[i])
148  return 0;
149  return -1;
150 }
151 
152 static int check_timecode(void *log_ctx, AVTimecode *tc)
153 {
154  if (tc->fps <= 0) {
155  av_log(log_ctx, AV_LOG_ERROR, "Timecode frame rate must be specified\n");
156  return AVERROR(EINVAL);
157  }
158  if ((tc->flags & AV_TIMECODE_FLAG_DROPFRAME) && tc->fps != 30 && tc->fps != 60) {
159  av_log(log_ctx, AV_LOG_ERROR, "Drop frame is only allowed with 30000/1001 or 60000/1001 FPS\n");
160  return AVERROR(EINVAL);
161  }
162  if (check_fps(tc->fps) < 0) {
163  av_log(log_ctx, AV_LOG_ERROR, "Timecode frame rate %d/%d not supported\n",
164  tc->rate.num, tc->rate.den);
165  return AVERROR_PATCHWELCOME;
166  }
167  return 0;
168 }
169 
170 static int fps_from_frame_rate(AVRational rate)
171 {
172  if (!rate.den || !rate.num)
173  return -1;
174  return (rate.num + rate.den/2) / rate.den;
175 }
176 
177 int av_timecode_check_frame_rate(AVRational rate)
178 {
179  return check_fps(fps_from_frame_rate(rate));
180 }
181 
182 int av_timecode_init(AVTimecode *tc, AVRational rate, int flags, int frame_start, void *log_ctx)
183 {
184  memset(tc, 0, sizeof(*tc));
185  tc->start = frame_start;
186  tc->flags = flags;
187  tc->rate = rate;
188  tc->fps = fps_from_frame_rate(rate);
189  return check_timecode(log_ctx, tc);
190 }
191 
192 int av_timecode_init_from_string(AVTimecode *tc, AVRational rate, const char *str, void *log_ctx)
193 {
194  char c;
195  int hh, mm, ss, ff, ret;
196 
197  if (sscanf(str, "%d:%d:%d%c%d", &hh, &mm, &ss, &c, &ff) != 5) {
198  av_log(log_ctx, AV_LOG_ERROR, "Unable to parse timecode, "
199  "syntax: hh:mm:ss[:;.]ff\n");
200  return AVERROR_INVALIDDATA;
201  }
202 
203  memset(tc, 0, sizeof(*tc));
204  tc->flags = c != ':' ? AV_TIMECODE_FLAG_DROPFRAME : 0; // drop if ';', '.', ...
205  tc->rate = rate;
206  tc->fps = fps_from_frame_rate(rate);
207 
208  ret = check_timecode(log_ctx, tc);
209  if (ret < 0)
210  return ret;
211 
212  tc->start = (hh*3600 + mm*60 + ss) * tc->fps + ff;
213  if (tc->flags & AV_TIMECODE_FLAG_DROPFRAME) { /* adjust frame number */
214  int tmins = 60*hh + mm;
215  tc->start -= 2 * (tmins - tmins/10);
216  }
217  return 0;
218 }
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