[x265] A few questions about the new VUI settings

[dave]

On 02/27/2014 11:38 PM, Selur wrote:
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> Got a bunch of questions and uncertainties about the new VUI settings,
> would be nice if someone could explain a bit what they are ment for.
>
>> --vui                         Add Video Useability Information with
>>   all fields to the SPS. Default disabled
> Does this have to be set for all the other options to work, if not what
> does it do?
No, it doesn't.  All it does is set all flags that cause the vui and 
optional parts of it to be added to the sps.  Without specifying any 
other vui cli options, the vui will only have default values.  I added 
this initially only for testing purposes but thought it might be useful 
beyond that.  If not, then it can be removed.  Just specifying any vui 
cli option by itself will cause a vui to be added to the sps.
>> --sar <int:int|int>           Sample Aspect Ratio, the ratio of
>> width to height of an individual pixel. Choose from 0=undef,
>> 1=1:1("square"), 2=12:11, 3=10:11, 4=16:11, 5=40:33, 6=24:11,
>> 7=20:11, 8=32:11, 9=80:33, 10=18:11, 11=15:11, 12=64:33, 13=160:99,
>>   14=4:3, 15=3:2, 16=2:1 or custom ratio of <int:int>. Default 0
> Is there a difference in I use --sar 1:1 or --sar 1 ?
No they will both cause the same result of apsectRatioIdc being set to 1.
>> --overscan <string>           Specify crop overscan setting from
>> undef, show or crop. Default undef
> I suspect this requires '--crop-rect <string>' to be set and decides
> what to do with the crop values.
> assuming the decoder supports it:
> show = should just 'overlay/show' the crop rectangle
> crop = should actually crop the output picture
> but what does 'undef' in this context mean? Does it mean that the
> decoder decides what to do with the crop rectangle values, does is mean
> 'ignore' the crop rectangle values or what is it ment to do?
Initially, I left out the undef option but since it's part of the x264 
--overscan cli option I added it.  The undef option means that overscan 
info is not included in the vui which is the default anyway so it really 
does nothing.  The decoder decides nothing.
>> --[no-]fieldseq ... --nal-hrd .. --subpichrd ..
> I suspect that these might be needed for some future blu-ray/avc-hd
> compatibility?
I am not sure.  I am new to x265 and haven't worked on x264 but I am 
sure there are others that can answer this for you.
>> --timinginfo                  Add timing information to the VUI.
>> Defaut disabled
> No sure what this is for since I doubt that it is the same as the time
> codes one normally finds in containers.
It's timing information in relation to the display of frames and general 
system clock information in units of ticks.
>> --bitstreamrestriction        Add bit stream restriction fields to
>>   the VUI. Default disabled
> I suspect that this is needed for later tier, profile, level signaling?
>
Probably.  Like I said, I am new to this and others may have a better 
answer.
>
> => got a lot of ideas what stuff might be, but some additional infos
> would be nice (and it might be a good idea to add these to the next
> 'x265 Evaluators Guide').
>
>
> Cu Selur
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