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n4.4.7
libavutil/timecode.c
272 строки
8 KB
Michael Niedermayer
avutil/timecode: Check for integer overflow in av_timecode_init_from_components()
05 май 2026, 19:55
Не верифицирован
05 май 2026, 19:55
950afa2
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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_framenum2(int framenum, int fps) { /* only works for multiples of NTSC 29.97 */ int drop_frames = 0; int d, m, frames_per_10mins; if (fps && fps % 30 == 0) { drop_frames = fps / 30 * 2; frames_per_10mins = fps / 30 * 17982; } else return framenum; d = framenum / frames_per_10mins; m = framenum % frames_per_10mins; return framenum + 9U * drop_frames * d + drop_frames * ((m - drop_frames) / (frames_per_10mins / 10)); } 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_framenum2(framenum, tc->fps); ff = framenum % fps; ss = framenum / fps % 60; mm = framenum / (fps*60LL) % 60; hh = framenum / (fps*3600LL) % 24; return av_timecode_get_smpte(tc->rate, drop, hh, mm, ss, ff); } uint32_t av_timecode_get_smpte(AVRational rate, int drop, int hh, int mm, int ss, int ff) { uint32_t tc = 0; /* For SMPTE 12-M timecodes, frame count is a special case if > 30 FPS. See SMPTE ST 12-1:2014 Sec 12.1 for more info. */ if (av_cmp_q(rate, (AVRational) {30, 1}) == 1) { if (ff % 2 == 1) { if (av_cmp_q(rate, (AVRational) {50, 1}) == 0) tc |= (1 << 7); else tc |= (1 << 23); } ff /= 2; } hh = hh % 24; mm = av_clip(mm, 0, 59); ss = av_clip(ss, 0, 59); ff = ff % 40; tc |= drop << 30; tc |= (ff / 10) << 28; tc |= (ff % 10) << 24; tc |= (ss / 10) << 20; tc |= (ss % 10) << 16; tc |= (mm / 10) << 12; tc |= (mm % 10) << 8; tc |= (hh / 10) << 4; tc |= (hh % 10); return tc; } 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_framenum2(framenum, fps); if (framenum < 0) { framenum = -framenum; neg = tc->flags & AV_TIMECODE_FLAG_ALLOWNEGATIVE; } ff = framenum % fps; ss = framenum / fps % 60; mm = framenum / (fps*60LL) % 60; hh = framenum / (fps*3600LL); 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_string2(char *buf, AVRational rate, uint32_t tcsmpte, int prevent_df, int skip_field) { 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 if (av_cmp_q(rate, (AVRational) {30, 1}) == 1) { ff <<= 1; if (!skip_field) { if (av_cmp_q(rate, (AVRational) {50, 1}) == 0) ff += !!(tcsmpte & 1 << 7); else ff += !!(tcsmpte & 1 << 23); } } snprintf(buf, AV_TIMECODE_STR_SIZE, "%02u:%02u:%02u%c%02u", hh, mm, ss, drop ? ';' : ':', ff); return buf; } char *av_timecode_make_smpte_tc_string(char *buf, uint32_t tcsmpte, int prevent_df) { return av_timecode_make_smpte_tc_string2(buf, (AVRational){30, 1}, tcsmpte, prevent_df, 1); } char *av_timecode_make_mpeg_tc_string(char *buf, uint32_t tc25bit) { snprintf(buf, AV_TIMECODE_STR_SIZE, "%02"PRIu32":%02"PRIu32":%02"PRIu32"%c%02"PRIu32, 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_fps(int fps) { int i; static const int supported_fps[] = { 24, 25, 30, 48, 50, 60, 100, 120, 150, }; for (i = 0; i < FF_ARRAY_ELEMS(supported_fps); i++) if (fps == supported_fps[i]) return 0; return -1; } static int check_timecode(void *log_ctx, AVTimecode *tc) { if ((int)tc->fps <= 0) { av_log(log_ctx, AV_LOG_ERROR, "Valid timecode frame rate must be specified. Minimum value is 1\n"); return AVERROR(EINVAL); } if ((tc->flags & AV_TIMECODE_FLAG_DROPFRAME) && tc->fps % 30 != 0) { av_log(log_ctx, AV_LOG_ERROR, "Drop frame is only allowed with multiples of 30000/1001 FPS\n"); return AVERROR(EINVAL); } if (check_fps(tc->fps) < 0) { av_log(log_ctx, AV_LOG_WARNING, "Using non-standard frame rate %d/%d\n", tc->rate.num, tc->rate.den); } return 0; } static int fps_from_frame_rate(AVRational rate) { if (!rate.den || !rate.num) return -1; return (rate.num + rate.den/2LL) / rate.den; } int av_timecode_check_frame_rate(AVRational rate) { return check_fps(fps_from_frame_rate(rate)); } 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_components(AVTimecode *tc, AVRational rate, int flags, int hh, int mm, int ss, int ff, void *log_ctx) { int ret; int64_t s; memset(tc, 0, sizeof(*tc)); tc->flags = flags; tc->rate = rate; tc->fps = fps_from_frame_rate(rate); ret = check_timecode(log_ctx, tc); if (ret < 0) return ret; s = hh*3600LL + mm*60LL + ss; if (s != (int32_t)s) return AVERROR(EINVAL); s = s * tc->fps + ff; if (s != (int32_t)s) return AVERROR(EINVAL); tc->start = s; if (tc->flags & AV_TIMECODE_FLAG_DROPFRAME) { /* adjust frame number */ int tmins = 60*hh + mm; tc->start -= (tc->fps / 30 * 2) * (tmins - tmins/10); } return 0; } int av_timecode_init_from_string(AVTimecode *tc, AVRational rate, const char *str, void *log_ctx) { char c; int hh, mm, ss, ff, flags; 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; } flags = c != ':' ? AV_TIMECODE_FLAG_DROPFRAME : 0; // drop if ';', '.', ... return av_timecode_init_from_components(tc, rate, flags, hh, mm, ss, ff, log_ctx); }