2013-02-17, 12:21
(2013-02-16, 16:39)davilla Wrote: Christ, [email protected], 16 ref frames. Idiots, that is way out of h264 spec.
Are you sure ? I've read a long time ago the spec from level part, and in level 4.1, you have only 4 ref frame at 1080p (but it means you can have 8 ref frame at 720p, and 16 with SD resolution, without breaking h264 specs), but it will not surprise me, that at level 5.1, you can go up to 16 ref frame.
I have in this specific case, other opinion. Anime is the exception which realy benefit of having more than 4 ref frame, and where using 16 ref frame is not a useless thing. So, quite to break HW compatibility, you have to go all the way, and do [email protected], using 16 ref frame, at least, it's logical. I found stupid [email protected] with 3 ref frame...
I had a pdf with some of the h264 spec, but i don't remember where i've put it on my PC...
Edit : I've found h264 spec.
For level 4.1, MaxDpbMbs is 32768. 1920/16=240 1080/16=67.5 -> 68
32768/(68x120)=4.01 -> 4 ref frame max.
For level 5.1, MaxDpbMbs is 184320.
184320/(68x120)=22,6 -> 22 ref frame max. 16 is lowel than max value possible with 5.1 level, so, no, it's absolutely not out of h264 spec. Now, if i'm wrong, or you have others informations, explain it.
(From T-REC-H.264-201201 document, p292).
Edit2 : A little mistake i'll correct : 16 is the maximum number of ref frame possible, as spec specify min(calculation,16). So, for 5.1 -> min(22,16) -> 16. So, 16 is not lower than max possible at 5.1, it's max possible at all levels.