[Matroska-devel] requesting "AvgTimePerFrame" or "FieldRate" header field

madshi madshi at gmail.com
Sat Dec 15 15:34:52 CET 2012


VC-1 and MPEG-2 store a frame rate which is identical to h264's field rate,
just with half the value. I don't have much knowledge about MPEG-4 part 2,
but I'd be extremely shocked if it wouldn't be identical to either MPEG-2
or h264.

There isn't really any difference between how VC-1, MPEG-2 and h264 store
FPS information in the header. The only difference is that h264 stores the
field rate while the others store the frame rate, which is always exactly
half of the field rate.

For example, MPEG-2 and VC-1 store 30000/1001 in the header for telecined
NTSC content (e.g. 24 encoded frames per second with "repeat_first_field =
1"), while h264 stores 60000/1001.

Best regards, Mathias.


2012/12/15 Moritz Bunkus <moritz at bunkus.org>

> Hey,
>
> On Sat, Dec 15, 2012 at 3:21 PM, madshi <madshi at gmail.com> wrote:
>
> > Ok, let's make it simple. What I'm suggesting is to simply use the h264
> > field rate (or "frame rate = field rate / 2") for the new MKV header
> field.
>
> Easy enough for h.264, sure. What about all the other video codecs and
> situations? VC1, MPEG-4 part 2 aka DivX/XviD, MPEG-2 etc. etc?
>
> Kind regards,
> mosu
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