[x264-devel] Re: [PATCH] add pps_id option and define sps_id and pps_id as uint8_t

[Loren Merritt]

On Thu, 1 Feb 2007, Limin Wang wrote:
> Loren Merritt [2007-01-31 15:30:04 -0700]:
>
>> I don't know why they need different ranges (since there's no penalty for
>> having unused numbers), but I can guess why you'd expect more PPSs than
>> SPSs. SPS contains properties of the decoded stream. PPS contains all the
>> settings that only the codec itself needs to know. So I'd expect multiple
>> SPSs only if you're concatenating video from different sources, but PPS
>> could change within each source if different scenes have different optimal
>> settings. (Ok, so the segregation isn't that perfect, but the idea
>> stands.)
>
> Thanks, it sounds reasonable. So I think pps_id and sps_id value should be
> decided by encode self instead of user configure. In order to get optimal
> encode result, it's necessary to support multiple PPS also. right?

The reason it's configurable in x264 is because that's easier than writing 
a program to take two streams with conflicting ids and renumber them so 
they can be concatenated. (mp4/mov/mkv only. Containers without global 
headers don't care if there are conflicting ids.)
If x264 used multiple PPS, I'd still have to have an option to specify 
which ids to use, until such a program exists.

--Loren Merritt

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