[Discussion] New Feature: Display Aspect Ratio

I just compiled the latest cvs, and saw this new feature. I recalled it being discussed a little bit on the mailing-list.

So everyone, what do you think about it? Bring it on!

[mf]

I can only say: FINALLY .

[unixfs]

I tested it encoding with mencoder and when I specified pal43
the final A/R was 1.02.
using ext:4:3 it came out as 1.09
I don't really understand how it's supposed to work.
can someone explain, please?

P.S. mplayer is already able to correctly read those fields,
it's been working correctly with libavcodec encodes for years.

[sysKin]

Originally posted by unixfs
I tested it encoding with mencoder and when I specified pal43
the final A/R was 1.02.
using ext:4:3 it came out as 1.09
I don't really understand how it's supposed to work.
can someone explain, please?

In mencoder, you are setting PAR not AR. PAR is pixel aspect ratio - describes the shape of each pixel. Accoriding to the standard, "pal43" means PAR of 12:11.

In VfW's gui, PAR is calculated on-the-fly using given AR and picture resolution. IMHO it should have been done better - but GUI sucks in so many places that this part blends in

Radek

[Koepi]

Ouch.

[bond]

i wanted to say that the 3ivx guys already found a way that:
1) is not container related of course (ie can be used in avi (works with the m$ splitter for example))
2) can already be played back in dshow (no need for mplayer or so)

try the following:
1) encode with the 3ivx vfw codec (by using the PAR option) to avi
2) when playing this avi, the set par will not be displayed
3) mux this avi to mp4
4) mux this mp4 to avi
5) play the resulting avi in dshow and enjoy the correct par

btw according to shitowax steps 3-4 can be left out if the codec would write the info directly during encoding

[shitowax]

Naughty naughty bond =)

[bond]

naughty by nature

[sysKin]

This sounds very good indeed.

Originally posted by bond
1) is not container related of course (ie can be used in avi (works with the m$ splitter for example))

Does it mean that it can be used in ogm too, if I'd mux to ogm instead of avi in step 4 ?

2) can already be played back in dshow (no need for mplayer or so)

3vix's dshow? If yes, what do I do to add this feature to XviD's dshow?

Radek

[bond]

Originally posted by sysKin
This sounds very good indeed.

well i already wrote about it on irc but i simply got ignored

Does it mean that it can be used in ogm too, if I'd mux to ogm instead of avi in step 4 ?

hm i didnt try it, but i think it has something to do with how the 3ivx mp4 muxer and than the splitter treats the info
but as i wrote it should be also possible to write this info directly into .avi during encoding (or with an own muxing app)

[sillKotscha]

glad to see that all of you are so happy about this feature... but it's the end of my horizon. What is the advantage out of it. I can't image any for my personal use - but as I said, sometimes I still have a deep lack of knowledge!!

thanks in advance

Sill

[olnima]

same with my horizon... :-)

maybe anybody could explain the Display-Aspect Ratio settings for those who are capturing videos directly (1-pass) using xvid and play them on a pc with the xvid decoder (koepis PreBeta3) on mediaplayerclassic or on a Standalone DVD-Player.

Thank You

Olnima

[unixfs]

For me it's useful because it permits to crop unwanted black borders
and encode without resizing (which usually introduces artefacts such as
excessive fading) keeping the original A/R .

[sysKin]

I have to admit I can't imagine me using it either. If I really wanted to do any AR stuff I'd start using matroska... but anyway, it's there, have fun everyone ;D

Radek

[bond]

it would be much more fun, if we could use it directly with the avi created by the xvid codec

edit: damn it seems that the nero video decoder already supports this
good stuff

[plazz2000]

Looks like this feature has been removed already. (it's not in gam3r's Dec18th build anyway...)

[olnima]

@plazzz: it has now it's own register-page and is still there.

Thanks to gamr for the instantbuilds.

Olnima

[Th3-S4int]

Can somebody explain me how that Feature works and for what it helps?

[bond]

anamorphic encoding (so using this ar feature to resize during playback (only in mplayer or with the nerovideodecoder fitler atm)) only makes sense when you dont use any resize filter when transcoding from dvd!

[Assault]

@ bond

Hmm....I don't know if that's true. AFAIK the human eye is more sensitive to vertical than to horizontal resolution. That means it is possible to get a better quality when you use a SMALLER horizontal but a BIGGER vertical resolution(you won't notice the loss of the horizontal res but you will notice the gain of increasing the vertical res). So IMHO using a PAR different than 1 can also make sense when you donwscale your resolution because you haven't enough bits.

Assault