aspect ratio problem

[thecrock]

I have two avi files that I want to convert for dvd playback on my standalone, the problem is the picture is distorted after encoding. Avi codec tells me that the res is 352*480, what would you suggest.

Peace.

I am using diko to convert, should I maybe use anamorphic (still a newbie, man).

[Alex_ander]

If your original aspect ratio was 16:9 and you directly encoded the file to MPEG (352x480 are the figures for half-resolution NTSC and that's inside DVD specs), then you already have that anamorphic (non-letterbox) encoding. To properly display the video in original aspect ratio a) the file should have proper 16:9 flags after encoding (MPEG encoders do this properly, but some simple convertors may not offer this setting) - then it will be OK on standalone and b) the software player you test it on should also support stretching lines for this aspect ratio (PowerDVD, WinDVD etc). If you original file was 4:3 and you use software player not suitable for DVDs, you also may see aspect ratio distortion due to half-resolution encoding (but maybe still OK on standalone after authoring).

[guns1inger]

You have a choice. You can resize to double the width (to 704 x 480) and encode - at which point you can make a call on 16:9 or 4:3, or simple encode it at half-D1 (the current resolution) and author as 4:3. A good software DVD player and all hardware DVD players will display half-D1 correctly.

It is unlikely to be 16:9 material at half-D1, and DVD half-D1 does not support 16:9.

[thecrock]

I forgot to say that I live in pal land so how do i resize to 720*576, and what should i use?

Thanks for the replies guys.

[jman98]

Converting a half height NTSC AVI file to full height PAL DVD is not going to be pretty, especially with any free tools. My suggestion would be to stick to NTSC resolutions as the odds are that your DVD player will play it correctlly. That way you'll only have to deal with potentially (unless you decide to stick with 352x480) upconverting the resolution of the AVI file and not also have the inevitable NTSC->PAL issues to deal with. Most people in PAL land can watch NTSC DVDs with no problems, but there is the odd person who has some weird old TV that only supports PAL. Hopefully that won't be the case for you. DVD players that support Divx are pretty cheap these days in the USA. I'm sure that's true in the UK. Have you considered just buying a DVD player that support Divx so you don't have to worry about converting everything? The player could pay for itself in saving you from having to do a bunch of unnecessary conversions to DVD since you could just watch the Divx files without converting them.

[thecrock]

My dvd will play ntsc but gives a flicker effect unless i convert to 25 fps. Is there a way of converting to 25 fps while keeping the ntsc ratio?

Thanks again.

[guns1inger]

Not that is playable. What do you mean by flicker effect ?

Consult your manual. Some players can playback NTSC natively, but are set to output as PAL or PAL60 by default. This doesn't give as good a result as native playback. I know LG ship like this in PAL land. Pioneer and others are usually set to native output by default.

[thecrock]

When I convert from 23 to 25fps the picture gets jerky when the camera pans, this does not happen when i encode with free enc bundled with diko but happens with other conversion software i have used, so it's not down to my standalone but the software used to encode from avi to dvd specs.

So like jman98 posted I want to keep the ntsc aspect ration but change from 23 fps(29fps is flagged but this is still really 23 fps isnt it?) to 25 fps without the jerky picture.

Ideas?

PEACE.

[guns1inger]

Resize to 352 x 576 (PAL resolution), but encode at 23.976 fps (NTSC). Once you have the mpeg file, run it through DGPulldown, choosing the 23.976 -> 25 fps option. This should now play as a PAL file, but without the jerkiness.

If the file is actually 29.97 fps then you cannot nicely bring it back to 25 fps without doing damage.

[thecrock]

By encoding at that size my picture will be stretched horizontally.

[guns1inger]

You can't keep the NTSC resolution unless you add black bars top and bottom. 25 fps is PAL and requires a PAL resolution. If you want to keep the NTSC resolution, you need to add 48 lines of black to the top and 48 to the bottom. You can do this with virtualdubmpeg2's resize filter. Load the video, add the resize filter, enter 720 x 480 in the top section. Tick expand frame and letter box image, and enter 720 x 576 in the bottom section. Now you can either save this to a lossless avi format (lagarith, huffyuv etc) or frameserve to your encoder. If you follow the pulldown method I posted earlier you should get smooth(er) playback, however the image will be distorted because this ignores the pixel aspect ratio. You will get a correct image aspect ratio only if you resize the image to 576 lines.

[thecrock]

Really, thanks for the help, but where do i find the resize filter?

[jagabo]

Video -> Filters -> Add -> Resize

[thecrock]

I dont get this, when i enter the dimensions guns1inger gave i get a squashed picture in the preview pane.

[jagabo]

First you have to understand that the display aspect ratio (DAR) is indepenedent of the pixel dimensions. Your 352x480 source isn't likely to have square pixels, it's probably either 4:3 or 16:9 DAR. By default VirtualDub shows you the frame using square pixels so you can see the "raw" pixels, not resized for DAR pixels.

Assuming the video is 4:3 DAR all you have to do is resize the frame from 352x480 to 352x576 (PAL frame size), then encode as MPEG2 for DVD, telling the encoder that your source should be displayed as 4:3. If you leave the frame rate at 23.976 then use DGPulldown to add pulldown flags (instructions that tell the DVD player how to produce 50 interlaced fields per second from the 23.976 frames per second progressive video).

[thecrock]

So I resize to 352 * 576 and save using hufffy or another lossless codec, then will I be able to encode as normal for dvd without the picture stretching?

[jagabo]

So I resize to 352 * 576 and save using hufffy or another lossless codec, then will I be able to encode as normal for dvd without the picture stretching?

If you tell the MPEG encoder that your video should be displayed at 4:3 the DVD player will display it as 4:3.

[thecrock]

I tried saving with lagarith but the picture suffers, this from a lossless codec? I must be doing something wrong!

[guns1inger]

What do you means "suffers" ? You may find you can't play it back smoothly because of the amount of data it needs to transfer, but this will not affect encoding to mpeg2.

[thecrock]

Thanks so much for all the help guys, really thanks.

I think the problem is cracked, I resized with virtualdub to 352*288 and saved with lagarith for lossless encoding, then loaded the file into diko and chose 704*576 with 4:3 ratio, I have encoded 5 mins of the movie and it looks MUCH better. I am now encoding the whole movie and as long as the audio stays in sync(can't see why it wont) I should have a decent conversion.

The reason I use diko for encoding from 23 to 25 fps is because I don't get any jumpy playback on my standalone but if i use say nero or convertxtodvd I get jumps. Freenc is the only encoder I know that can handle the conversion really well and as I dont write script it has a nice gui in diko.

Thanks again you guys,

PEACE.

[guns1inger]

Why did you resize to 352 x 288, then resize again to 504 x 576 ? You could have kept the entire vertical resolution and just resized to 704 x 576 in virtualdub. You have now thrown away half the vertical data.

[thecrock]

I resized to 288*352 because this is a pal resolution, then to 704*576 because this is a resolution used in diko settings and is twice the size of my resize. and I most certainly haven't lost half vertical resolution. The picture looks very good after encoding with the new sizing but oops the audio is out of sync, guess i'll have to save to wave.

Does that make sense guns1inger?

[jagabo]

You lost 40 percent of your resolution (288/480), not 50.

[guns1inger]

No. I still would have just resized it straight to 704 x 576, keeping all of the original 480 lines worth of image. But each to their own.