> On Jan 13, 2016, at 9:25 AM, Bouke / VideoToolShed <bo...@videotoolshed.com> > wrote: >> On Jan 13, 2016, at 14:17, Robert Krüger <krue...@lesspain.de> wrote: >> >> On Wed, Jan 13, 2016 at 12:53 PM, Christoph Gerstbauer < >> christophgerstba...@gmail.com> wrote: >> >>> FFmpeg allows me to set a timecode of 24:00:00:00 and beyond. >>> >>> e.g "-timecode 24:00:00:00" >>> >>> When I make an MXF D10 for example, the value of 24:00:00:00 is still in >>> the file. >>> Most but not all programs ignore this and display 00:00:00:00 correctly. >>> >>> Here are some sample extractions of the timecode offset value in different >>> mxf d10 files generated by ffmpeg: >>> >>> PAL 25fps: >>> >>> -timecode 12:34:56:11 -> in file: 11477b hex -> 1132411 dec >>> >>> -timecode 10:00:00:00 -> in file: 0dbba0 hex -> 900000 dec >>> >>> -timecode 20:00:00:00 -> in file: 1b7740 hex -> 1800000 dec >>> >>> -timecode 23:59:59:24 -> in file: 20f57f hex -> 2159999 dec >>> >>> -timecode 24:00:00:00 -> in file: 20f580 hex -> 2160000 dec -> 24h >>> >>> -timecode 24:00:00:01 -> in file: 20f581 hex -> 2160001 dec >>> >>> -timecode 25:00:00:00 -> in file: 225510 hex -> 2250000 dec -> 25h >>> >>> >>> NTSC 30fps >>> >>> -timecode 23:59:59;29 -> in file: 2782df hex -> 2589407 dec >>> >>> -timecode 24:00:00;00 -> in file: 2782e0 hex -> 2589408 dec >>> >>> >>> Why is this possible to set a timecode after 23:59:59:XX? >>> Is there a usecase? >>> >> >> I wasn't able to find any official spec that says what the limit for the >> hour part is but since it in the general case does not define a time of day >> but an offset, why limit it to 25 hours and not use the full 100? On a >> side-note, I have not come across a real-world use case for a timecode of >> that magnitude either. >> > Some forms of TC just lack the space to store higher numbers IIRC (LTC / > VITC, perhaps also in MpegII frame headers) > But there is logic in not going higher, as it is ‘time’. > For a real world use case, in the old days of tape, a reelname most of the > time corresponded with the hour. > So a production with more than 24 tapes needed better administration in reel > names that had to be written on the tape and box.
FWIW QuickTime timecode flags includes a "24 hour max" flag to clarify when it is and is not enabled in a timecode track, but >24 hour values are certainly allowed in the QuickTime spec. https://developer.apple.com/library/mac/documentation/QuickTime/QTFF/QTFFChap3/qtff3.html <https://developer.apple.com/library/mac/documentation/QuickTime/QTFF/QTFFChap3/qtff3.html> Dave Rice _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
