[FFmpeg-user] Converting a 23.98p source to 29.97i ProRes w/interlaced 3:2 pulldown?

Moritz Barsnick barsnick at gmx.net
Mon Oct 26 23:30:30 CET 2015

On Mon, Oct 26, 2015 at 12:06:30 -1000, Mel Matsuoka wrote:
> So is the bottom line that FFmpeg favors overt pedanticism in regards to
> defining frame rates, hence the need for the user to actually provide it
> with the actual math required to define a true NTSC framerate?

No, YOU should be pedantic or precise for your own sake. No good taking
30000/1001 input and making 29.97 out of it (not that the numbers
differ very much). ffmpeg will do whatever you tell it to, for better
or worse.

Apart from that, making a "more" standard conformant file might just be
better for some cases. Some people tend to use "30" instead of 29.97,
just because it's easier. Apart from the actual frame dupes, I don't
know if e.g. a DVD mastered with that rate is actually fine by strict

OTOH, if your material is any other rate, and you just want to play in
a SW player, I don't see a point in actually *converting*. But when
creating new content, just be precise. My $0.02.

> Is it bad form to simply use the "ntsc" and/or "ntsc-film" aliases,
> instead of using the fractional forms?

In my opinion: Not at all. That's exactly what they're designed and
useful for. (And save you remembering the fractions.)

But this drifted off the original topic: Carl Eugen pointed out that
the output rate of the filter should already be correct, assuming a
correct input rate, so no need to "transform" to 30000/1001 using "-r".
Have you been able to confirm or deny?


More information about the ffmpeg-user mailing list