text: /*
   * 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 NTSC 29.97 and 59.94 */
      int drop_frames = 0;
      int d, m, frames_per_10mins;
  
      if (fps == 30) {
          drop_frames = 2;
          frames_per_10mins = 17982;
      } else if (fps == 60) {
          drop_frames = 4;
          frames_per_10mins = 35964;
      } else
          return framenum;
  
      d = framenum / frames_per_10mins;
      m = framenum % frames_per_10mins;
  
      return framenum + 9 * 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*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_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*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_fps(int fps)
  {
      int i;
      static const int supported_fps[] = {24, 25, 30, 50, 60};
  
      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 (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 && tc->fps != 60) {
          av_log(log_ctx, AV_LOG_ERROR, "Drop frame is only allowed with 30000/1001 or 60000/1001 FPS\n");
          return AVERROR(EINVAL);
      }
      if (check_fps(tc->fps) < 0) {
          av_log(log_ctx, AV_LOG_ERROR, "Timecode frame rate %d/%d not supported\n",
                 tc->rate.num, tc->rate.den);
          return AVERROR_PATCHWELCOME;
      }
      return 0;
  }
  
  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_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_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;
  }
  