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

Michael Niedermayer michaelni
Sun Apr 15 18:00:08 CEST 2007


On Sun, Apr 15, 2007 at 05:40:52PM +0200, Baptiste Coudurier wrote:
> 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
> exist."

iam asking for a specific use case where the user settable drop frame
timecode flag is needed, your quote above speaks about common practices
and their consequences, its unclear from the text which actual equipment
behaves like that
either way theres no reason why ffmpeg should behave like that so the
consequences claimed by the text dont apply ...

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

When you are offended at any man's fault, turn to yourself and study your
own failings. Then you will forget your anger. -- Epictetus
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