View Full Version : Resolutions (1.78:1)

22nd February 2002, 14:50
Simple DivX (this seemed a general question) question -

2.35:1 films: 640x272, 576x240, 512x224
1.85:1 films: 640x352, 576x304, 512x272
1.78:1 films: ???x???, ???x???, ???x???
1.33:1 films: 640x480, 576x432, 512x384

I am stuck on 1.78:1, I have searched the forum a few times with no luck could somebody please tell me adequate resoultion for DivX at 1.78:1? Thanks in advance

22nd February 2002, 16:52
Doh - So stupid all i needed to do was put the ration of 1.78:1 into Gknot and it tells you. Sorry. Admin you can delete this post -

So are these correct -

If anybody thinks differently please reply with other values

22nd February 2002, 21:40
You can calculate this yourself:

640 / 1.78 = 360
but 360 isn't a multiple of 16 so you should take 352 (22 x 16) in stead.

All the values are correct in your post :D

24th February 2002, 09:47
why does it need to be a multiple of 16?

24th February 2002, 11:18
nice avatar Slogar...

for encoding,reproducing reasons
x32 is still better

24th February 2002, 17:13
what are reproducing reasons? i think i often crop movies in virtual dub to multiples that aren't of 8. or does it crop more than I want to make it 8x without telling me?

24th February 2002, 17:38
The hardware overlay of several videocards only support 16x.

24th February 2002, 22:07
you should always use a horizontal size divisible for 16
for vertical 8 could be enough
really dont go under 4!!

24th February 2002, 22:10
the horizontal size should be didvidable by 32 for some gfx cards, not 16.
the height is not important for playback, but maybe it gives you a lower quality during encoding.

24th February 2002, 22:24
oh yeah, i forgot that i resize to 640x480 or something after cropping. i always hate how DVD2AVI only let's me crop in huge sections of like 8 pixels or more and it makes it balance between the top and bottom and stuff. i then sometimes add smaller increments after i'm done using virtualdub through VFAPI. I would only use VirtualDub and not DVD2AVI for cropping, but I remember a long time ago when VirtualDub would mess up and not crop correctly, and i would turn the cropping on and off and slide the bar, and then whehn i turned it off and back on the picture would be in a different place and not cropped correctly. strange. (probably no one understood what I just typed though :))

13th June 2002, 14:11
Found a thread about 1.78:1 movies it seems :D

Anyhow; to me it seems like there's two focuses one could have here;
* Optimize for correct AR
* Optimize for TV-output

On 1.78:1 (1.777...:1) movies, one could then choose between a couple of resolutions (all multiples of 16 of course):

624 x 336
624 x 352
640 x 352
640 x 368

If you take AR in regard, this will for the resolutions give:

640 / 1.777 ~ 360,158
>> closest multiple of 16 = 368 (352=-8,158, 368 = +7,842)
AR offset = 368/360,158 ~ 2.177% (352/360,158 ~ 2.265%)

624 / 1.777 ~ 351,154
>> closest multiple of 16 = 352
AR offset: 352/351,154 ~ 0.241%

So the two "best" resolutions seems thereby to be 640 x 368 and 624 x 352 for 1.78:1 movies... or?! ;)

Now some say that one should stick below 1% AR offset... but really? What is more important? Not having to resize for TV output (640 x 368) and have a ~2% AR offset, OR having to resize but have a more correct AR (624 x 352)?

Personally, I think that having a 2% AR offset is totally unnoticable (ie; 640 x 368), and i'd rather optimize the movies for the screen output, since rezising movies in most players (especially DirectShow based one's - WMP etc) will result in a bad movie image.

Oh well, what do you think? Perhaps i've calculated wrong too hehe.. I dunno?

13th June 2002, 15:33
just crop a bit on the right and left side and you have correct ar in every resolution you want.

13th June 2002, 15:45
Originally posted by PeterTheMaster
just crop a bit on the right and left side and you have correct ar in every resolution you want. That is just so true! :D

Hehe.. I just got pointed in that direction too :o Silly me ;) 640x352 with a little cropping will do just fine I guess :D