[x264-devel] Re: VUI: 2 * num_units_in_tick / time_scale = frame_time

[Måns Rullgård]

Tuukka Toivonen said:
> Hi, noticed this discussion in mp4tech list:
>
> http://lists.mpegif.org/pipermail/mp4-tech/2005-July/005700.html
>
> seems like x264 gets it wrong too. Not that I would understand
> the standard, but I would trust Gary and the other folks there =)
> (actually Gary's comment is not yet in the archives but he
> seems to basically agree with John Cox)
>
> Attached patch should fix this.

I'll catch up with it tomorrow.  I had an email discussion with Peter
Gubanov at Moonlight about this issue last year, and the present variant
was the most reasonable thing we could think of that worked with other
decoders.  The latest issue of the standard is a bit more clear, but it
still makes my head hurt.

> Also, seems like I can't specify NTSC frame rate exactly.
>
> ./x264 --frames 10 --fps 29.970
> analyze: READ num_units_in_tick                        : [32] 1000
> analyze: READ time_scale                               : [32] 59936
> -> 29.968 fps
>
> ./x264 --frames 10 --fps 30000/1001
> analyze: READ num_units_in_tick                        : [32] 1000
> analyze: READ time_scale                               : [32] 60000
> -> 30 fps

That's a bit strange.  Those values should (or could) be written directly
into the VUI structure.

-- 
Måns Rullgård
mru at inprovide.com

-- 
This is the x264-devel mailing-list
To unsubscribe, go to: http://developers.videolan.org/lists.html