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 
av_timecode_adjust_ntsc_framenum2(int framenum,int fps)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 
av_timecode_get_smpte_from_framenum(const AVTimecode * tc,int framenum)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 
av_timecode_make_string(const AVTimecode * tc,char * buf,int framenum)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 
bcd2uint(uint8_t bcd)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 
av_timecode_make_smpte_tc_string(char * buf,uint32_t tcsmpte,int prevent_df)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 
av_timecode_make_mpeg_tc_string(char * buf,uint32_t tc25bit)130 char *av_timecode_make_mpeg_tc_string(char *buf, uint32_t tc25bit)
131 {
132     snprintf(buf, AV_TIMECODE_STR_SIZE,
133              "%02"PRIu32":%02"PRIu32":%02"PRIu32"%c%02"PRIu32,
134              tc25bit>>19 & 0x1f,              // 5-bit hours
135              tc25bit>>13 & 0x3f,              // 6-bit minutes
136              tc25bit>>6  & 0x3f,              // 6-bit seconds
137              tc25bit     & 1<<24 ? ';' : ':', // 1-bit drop flag
138              tc25bit     & 0x3f);             // 6-bit frames
139     return buf;
140 }
141 
check_fps(int fps)142 static int check_fps(int fps)
143 {
144     int i;
145     static const int supported_fps[] = {
146         24, 25, 30, 48, 50, 60, 100, 120, 150,
147     };
148 
149     for (i = 0; i < FF_ARRAY_ELEMS(supported_fps); i++)
150         if (fps == supported_fps[i])
151             return 0;
152     return -1;
153 }
154 
check_timecode(void * log_ctx,AVTimecode * tc)155 static int check_timecode(void *log_ctx, AVTimecode *tc)
156 {
157     if ((int)tc->fps <= 0) {
158         av_log(log_ctx, AV_LOG_ERROR, "Valid timecode frame rate must be specified. Minimum value is 1\n");
159         return AVERROR(EINVAL);
160     }
161     if ((tc->flags & AV_TIMECODE_FLAG_DROPFRAME) && tc->fps != 30 && tc->fps != 60) {
162         av_log(log_ctx, AV_LOG_ERROR, "Drop frame is only allowed with 30000/1001 or 60000/1001 FPS\n");
163         return AVERROR(EINVAL);
164     }
165     if (check_fps(tc->fps) < 0) {
166         av_log(log_ctx, AV_LOG_WARNING, "Using non-standard frame rate %d/%d\n",
167                tc->rate.num, tc->rate.den);
168     }
169     return 0;
170 }
171 
fps_from_frame_rate(AVRational rate)172 static int fps_from_frame_rate(AVRational rate)
173 {
174     if (!rate.den || !rate.num)
175         return -1;
176     return (rate.num + rate.den/2) / rate.den;
177 }
178 
av_timecode_check_frame_rate(AVRational rate)179 int av_timecode_check_frame_rate(AVRational rate)
180 {
181     return check_fps(fps_from_frame_rate(rate));
182 }
183 
av_timecode_init(AVTimecode * tc,AVRational rate,int flags,int frame_start,void * log_ctx)184 int av_timecode_init(AVTimecode *tc, AVRational rate, int flags, int frame_start, void *log_ctx)
185 {
186     memset(tc, 0, sizeof(*tc));
187     tc->start = frame_start;
188     tc->flags = flags;
189     tc->rate  = rate;
190     tc->fps   = fps_from_frame_rate(rate);
191     return check_timecode(log_ctx, tc);
192 }
193 
av_timecode_init_from_string(AVTimecode * tc,AVRational rate,const char * str,void * log_ctx)194 int av_timecode_init_from_string(AVTimecode *tc, AVRational rate, const char *str, void *log_ctx)
195 {
196     char c;
197     int hh, mm, ss, ff, ret;
198 
199     if (sscanf(str, "%d:%d:%d%c%d", &hh, &mm, &ss, &c, &ff) != 5) {
200         av_log(log_ctx, AV_LOG_ERROR, "Unable to parse timecode, "
201                                       "syntax: hh:mm:ss[:;.]ff\n");
202         return AVERROR_INVALIDDATA;
203     }
204 
205     memset(tc, 0, sizeof(*tc));
206     tc->flags = c != ':' ? AV_TIMECODE_FLAG_DROPFRAME : 0; // drop if ';', '.', ...
207     tc->rate  = rate;
208     tc->fps   = fps_from_frame_rate(rate);
209 
210     ret = check_timecode(log_ctx, tc);
211     if (ret < 0)
212         return ret;
213 
214     tc->start = (hh*3600 + mm*60 + ss) * tc->fps + ff;
215     if (tc->flags & AV_TIMECODE_FLAG_DROPFRAME) { /* adjust frame number */
216         int tmins = 60*hh + mm;
217         tc->start -= (tc->fps == 30 ? 2 : 4) * (tmins - tmins/10);
218     }
219     return 0;
220 }
221