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

Baptiste Coudurier baptiste.coudurier
Sun Apr 15 18:05:21 CEST 2007

Michael Niedermayer wrote:
> Hi
> 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

VTR, broadcast servers.

> either way theres no reason why ffmpeg should behave like that so the
> consequences claimed by the text dont apply ...

Why removing the POSSIBILITY to behave like that if the user wants to?
That justifies a fork.

Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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