[Ffmpeg-devel] [PATCH] remove drop timecode flag

Baptiste Coudurier baptiste.coudurier
Sun Apr 15 17:40:52 CEST 2007

Michael Niedermayer wrote:
> Hi
> On Sun, Apr 15, 2007 at 05:17:38PM +0200, Baptiste Coudurier wrote:
>> Michael Niedermayer wrote:
>>> Hi
>>> attached patch removes the drop timecode encoding support
>>> reasoning is that iam not aware of any use (not even obscure) of this feature
>> It is used when using 29.97 frame rate, when real time elapsed does not
>> correspond to frame number.
> drop frame timecode CAN but doesnt HAS to be used with 30000/1001 fps
> iam asking if there is a case where it HAS to be used. if you do not know
> of such a case then dont reply
> if you know of such a case, explain it to us please

Read the paper:

"NTSC colour signals have an actual frequency of close to 29.97
frames-per-second. As cue points must be located at frame boundries,
this figure is normally rounded up to 30 frames-per-second, causing an
excess of 108 frames per hour.

To eliminate these 108 frames each hour, two specific time code frame
values are dropped each minute (2x60=120), except every 10th minute
(2x60-2x6=108). The time code values dropped are specified as the first
two frames of a minute. Thus, the time code number following 01:04:59:29
would be 01:05:00:02, time code frames 01:05:00:00 and 01:05:00:01 don't

Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
SMARTJOG S.A.                                    http://www.smartjog.com
Key fingerprint                 8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA
Phone: +33 1 49966312

More information about the ffmpeg-devel mailing list