Megui aspect ratio...a little confused please help.

[Mikey1000]

Greetings. I seem to have a problem trying to convert some of my anime dvd's with megui. I selected anamorphic encoding and resize to mod 16 option, i cropped what was needed of the edges and decided to keep the full resolution of the dvd which is 720x480 4/3. I chose anime good quality profile and a bitrate of 1600kbps.
The problem i have is that the resulting output is only 640x480! I in no way remember setting it up to resize from the original dvd resolution...can someone please tell me is this normal? Did it downscale the video or what hapenned?
Media info says this about the mkv...it sees it as a 720x480 but media player classic or any player only outputs 640x480.

Format : Matroska
File size : 302 MiB
PlayTime : 23mn 5s
Bit rate : 1831 Kbps
Width : 720 pixels
Height : 480 pixels
Display Aspect ratio : 4/3
Frame rate : 23.976 fps
Standard : NTSC

[Sharktooth]

Probably you encountered the AR bug...

[Mikey1000]

I searched the forums but didn't find this bug...can you please elaborate?

[Sharktooth]

Try again, the forum is full of info about the megui anamorphic encoding bug.
it is also reported in the MeGUI bug-tracker.

[Mikey1000]

I found that thread but it's all too complicated for a newbie like me to understand...from what i get it i'll use a older version of megui. However is there anything i can do with the already encoded videos?

[Snarko]

I'm no expert, but it seems to me that 640x480 *is* the correct anamorphic resolution for a 4:3 DVD. An NTSC DVD only has 480 lines of resolution vertically, while 720 divided by 4/3 leaves you with 540. You'd have to upsize to get 720x540 from an NTSC DVD for 4:3 content. Of course, for any other standard anamorphic encode, the 720 is the upper limit of resolution and the vertical resolution scales down from there according to the aspect ratio. In the case of 4:3, 480 is the limiter, since 4:3 is a lower ratio than a DVD's 3:2.

[Sharktooth]

oh, NTSC... i just missed the "NTSC"...

[Snarko]

It just occurred to me that a 16:9 anamorphic encodes leaves me with 853x480, so the above 'reasoning' may seem suspect. I'm pretty sure that's a result of non-square pixels found on a DVD vs. square pixel encoding. DVD pixels being wider horizontally than vertically, it takes 853 square pixels wide to house the detail in a 720 nonsquare pixels wide DVD image. Or something like that. I think.

[Mikey1000]

I'm no expert, but it seems to me that 640x480 *is* the correct anamorphic resolution for a 4:3 DVD. An NTSC DVD only has 480 lines of resolution vertically, while 720 divided by 4/3 leaves you with 540. You'd have to upsize to get 720x540 from an NTSC DVD for 4:3 content. Of course, for any other standard anamorphic encode, the 720 is the upper limit of resolution and the vertical resolution scales down from there according to the aspect ratio. In the case of 4:3, 480 is the limiter, since 4:3 is a lower ratio than a DVD's 3:2.

So you're saying megui didn't mess up? It just seems weird to me. One other thing, when i take a screenshot from the 640x480 video it comes out in 720x480...so now i'm totally stomped.

[Sharktooth]

that's correct. tha't how anamorphic works.
if you dont know what anamorphic is, dont encode anamorphically.

[Snarko]

I doubt it messed up. AFAIK, anamorphic encoding is about keeping the resolution exactly as input while simply signalling what aspect ratio the image should have at playback. This means the 640x480 as reported during playback is correct: That's the right aspect ratio for 480 lines of information, without upsizing. And 720x480 is also correct: that's the resolution in the file/encode itself. Because the file is anamorphic, it just signals to an anamorphic-aware decode stream how to display the content at the proper aspect ratio. So a reported 853x480 is also right for 16:9 content, 853x363 (horizontally limited resolution here, remember) is right for 2.35 content and 640x480 is right for 4:3 content (vertically limited). I'd hazard a guess that perhaps the screenshot's aspect ratio is different than the video during playback (unless your viewer software handles nonsquare pixels on the fly too - I have no idea how nonsquare works in the static image realm).

[Mikey1000]

Ok...so it's there is no quality loss from resizing as i understand it.

[Snarko]

Right. That's why there's no resize step in the avisynth script if you overcrop for mod16 or just encode to non-mod16.

[sreg0r]

I am having a problem with the aspect ratio of a non-anamorphic 4:3 NTSC DVD using megui 0.3.0.1020

Using the Avisynth script creator it automatically selects the correct input DAR of ITU 4:3
When I view the file info using MediaInfo it reports the first video stream as

Width : 720 pixels
Height : 480 pixels
Display aspect ratio : 1.500
Frame rate : 23.976 fps
Standard : NTSC


As you can see for some reason the Aspect Ration is set as 1.5. Using MKVMerge I am able to manually set the AR to the correct 4:3 and remux no problems

Am I doing something wrong in the encoding process to have caused this or is it just a minor bug. This is my first rip using megui/x264 and I followed the guide on the megui wiki

[poisondeathray]

@sreg0r

Did you have the DAR set in your .avs script?

global MeGUI_darx = 4
global MeGUI_dary = 3

[sreg0r]

@sreg0r

Did you have the DAR set in your .avs script?

global MeGUI_darx = 4
global MeGUI_dary = 3

Looking at my avs I do not have those 2 lines

DGDecode_mpeg2source("C:\ripped\FREAKS_GEEKS_D1\VIDEO_TS\VTS_01_1.d2v",info=3)
ColorMatrix(hints=true)
#deinterlace
#crop
#resize
Undot() # Minimal Noise


So I just copy and paste them at the bottom of my avs file?

Excuse my ignorance but what does setting the input DAR to ITU 4:3 NTSC (1.367088) actually do?

[poisondeathray]

I usually put it at the top, and it seems to work fine for me

http://mewiki.project357.com/wiki/MeGUI/Aspect_Ratio_Signalling_in_AviSynth_Scripts

When you input the .avs, and the preview window opens, you can checkmark the box "show DAR" and it will show the correct preview. Just encode 100 frames to test if it works ok for you: Trim (0,100) - should only take a minute

I have no idea what the input DAR to ITU... thing is? Is that with the script creator? I don't use it.