WinAvi - Converting to MPEG-2

[hadenp]

Using WinAvi, I have converted a couple tv episodes.
Source is encoded: DivX avi
Output is: MPEG-2, (because I'd like to make a menu for the episodes.)

Selecting MPEG-2 for the output, the width/height default to 320 x 240 - which looks small when I play them back using my mpg viewer, PowerDVD. Also, the aspect ratio seems off - taller rather than wider, though I can fix this by selecting "force to 4:3"; then it looks letter boxed.

My question is: Will this play back "well" (meaning, fill the entire screen of a normal TV without a lot of graininess) OR do I need to increase the pixel width/height to get good results? Is there an optimum width/height to use or does one just experiment?

This is my first try at conversion.

Thanks.

[Baldrick]

320x240 is not dvd compliant. Use 352x240 or 352x480 or 720x480.

[jbodin]

I had to do just this very type of conversion -- I had downloaded an AVI file that was DivX encoded, and it was an odd size (it was sized at 320x235, slightly smaller than the standard 352x240 VCD format). I tried doing a simple resize to 352x240 conversion to a VCD-compliant MPEG1 file using TMPGenc, and the result looked HORRIBLE, even using my WinDVD viewer on my PC -- the picture was grainy and blocky, and the quality was VERY disappointing.

I looked around and found the following tutorial,which helped a lot:

https://www.videohelp.com/forum/userguides/91597.php

Pay special attention to the following portion:

Now for the important part - hit settings on TMPGEnc and select the Advanced tab -- set the Video Arrange Method to Center (Keep Aspect Ratio) and make sure your Source Aspect Ratio is 1:1

[what we are doing here is telling TMPGEnc to leave the resolution as it is but create an output with borders --- this reduces the amount of macro blocks created by MPEG encoding since TMPGEnc does not have to resize the source -- with these type of low bitrate source files resizing them to fit 352x240 or 352x288 creates a lot of problems and reduces the overall quality of the final MPEG]

In my example the result will be a 352x288 VCD with the 320x240 source preserved - it will leave some black borders when you play it back on your DVD but the results are much better than using Full Screen (Keep Aspect Ratio) as your Video Arrange Method.

The tutorial includes a sample showing the black border. The border might seem annoying/distracting, but the results are so much better than what I achieved by doing a simple stretch/resize that it is WELL worth it, IMO.

The file I was working with (part two of a Superman: The Animated Series episode) also had a LOT of "dot crawl," which further detracted from the picture quality. I did a LOT of processing using VirtualDub filters to clean up the picture, and I'm pretty pleased with the end result.

In your case, it sounds like you might only be dealing with a size issue, so you might be able to get away without the need to do that type of video cleanup ( hopefully! ).

Hope this helps a bit!

[hadenp]

Thanks for the info, Baldrick. I will check out the tutorial jbodin.

Some follow up: I see that the original DivX .avi is 512 x 384, which is 4:3. I would like to maintain that aspect ratio, because I think that's what would "look good" on the TV display. But even when I explicitly set the output MPEG-2 to those dimensions, it doesn't appear to be 4:3 in my viewer - i.e. it appears taller than it is wide.

1. Does that matter, in terms of how it will display on the tv screen?

Maybe that's just the viewer I'm using or is it due to differences between MPEG-2 and MPEG-4?

2. Can a small format (352 x 240) image "fill up" the TV screen ?

Thanks!

[jbodin]

2. Can a small format (352 x 240) image "fill up" the TV screen ?

Yes -- it's not DVD quality, but a good, clean result looks about as good as a VHS tape. In the NTSC world, 352 x 240 is the standard format for VCD images:

https://www.videohelp.com/vcd

I do a lot of cartoon captures at this resolution -- I can get about 3 half-hour episodes on a standard 80-minute CD. My kids love the commercial-free VCDs I make for them, and the quality is definitely watchable on a standard 27" TV.

You say that when you select MPEG-2 for the output, the width/height default to 320 x 240 -- this sounds odd, because MPEG1 352 x 240 is the NTSC VCD standard, and 480 xs 480 MPEG2 is the NTSC SVCD standard. Not sure what standard your default is trying to default to. If the original AVI file is 320 x 240, WinAVI may just be defaulting to the size of your source file. This is where the tutorial I pointed out will come in handy, because it sounds like you're going to have to convert a non-standard DivX format to a more standard size.

[hadenp]

jbodin - I appreciate your responses.

I see that I wasn't specific about my target output format - which is DVD, not VCD. My object is to covert DivX to "good looking" MPEG-2s that I can use to author a DVD. Like your source, these are cartoons.

My problem is aspect ration. It seems that aspect ratios vary depending on format...(VCD,SVCD,DVD). Is that correct? The reason I'm saying this is that if I divide 512 / 384 (that's what my source DivX is) I see that it's 1.333 or 4:3. But you and Baldrick suggest 352 x 240 which is 1.46. Why is that?

VCD, SVCD? Hmmmmm.... I wasn't really thinking about these - though perhaps I should. What's would be the advantage over DVD by the way...cost per disk?

Thanks!

[bugster]

Don't calculate aspect ratios according to the resolution. A TV does not have square pixels, so you can't do that.

VCD and SVCD only support a Display Aspect ratio (DAR) of 4:3. So in that respect the resolution of the mpeg doesn't matter, it will be displayed as 4:3. DVD also supports 16:9 DAR when you use full D1 resolution (720x480 for NTSC).

Probably easiest to do is use Tmpgenc for the conversion. Load the relevant DVD template and in advanced settings, set it to use 'full screen, keep aspect ratio'. Set the DAR to suit your TV and encode. TmpGenc will resize correctly for you, adding black bars top and bottom if required.

[jbodin]

Probably easiest to do is use Tmpgenc for the conversion. Load the relevant DVD template and in advanced settings, set it to use 'full screen, keep aspect ratio'. Set the DAR to suit your TV and encode. TmpGenc will resize correctly for you, adding black bars top and bottom if required.

That makes sense, but if you re-size a file that was originally 320 x 235 up to full D1 resolution (720x480 for NTSC), you would also probably need to enable "smoothing" or such in TMPGenc in order to help clean up the picture, correct? I thought it was always relatively easy to make something smaller (as in reducing a DVD-compliant MPEG2 image down to SVCD or VCD resolutions), but I thought it got a bit more tricky when you're dealing with a small source that you want to convert to a larger size, mainly because a smaller image source already contains less detail, and sizing it up won't increase the detail any, and may also reveal more of the defects.

[jbodin]

VCD, SVCD? Hmmmmm.... I wasn't really thinking about these - though perhaps I should. What's would be the advantage over DVD by the way...cost per disk?

Cost per disk is one advantage -- for me, the fact that all I need is my CD-RW drive is the #1 benefit of going with the VCD or SVCD format; since I don't have a DVD burner in my system, the VCD and SVCD format allows me to create videos for my kids using just my CD burner.

The other advantage is that if you're dealing with a file that is small to begin with, sizing it up to DVD-compatible size won't increase the amount of detail or image quality, and you may have to do more image processing to remove artifacts (macroblocks, etc.).

The main DISadvantage of the SVCD and VCD format is that you can't put as much video on a CD as you can on a DVD -- I can only get about 60 minutes' worth of video (3 cartoon episodes minus commercials) on a single VCD. If your source file is longer than 60 minutes, you'll probably need to split it across multiple VCDs, or move up to a DVD-compliant format so you can put it all on a single DVD.

I'm no expert, though -- I'm sure others can give you better advice overall, but I thought I'd share a bit of my own personal experience as a fellow newbie!

[bugster]

Probably easiest to do is use Tmpgenc for the conversion. Load the relevant DVD template and in advanced settings, set it to use 'full screen, keep aspect ratio'. Set the DAR to suit your TV and encode. TmpGenc will resize correctly for you, adding black bars top and bottom if required.

That makes sense, but if you re-size a file that was originally 320 x 235 up to full D1 resolution (720x480 for NTSC), you would also probably need to enable "smoothing" or such in TMPGenc in order to help clean up the picture, correct? I thought it was always relatively easy to make something smaller (as in reducing a DVD-compliant MPEG2 image down to SVCD or VCD resolutions), but I thought it got a bit more tricky when you're dealing with a small source that you want to convert to a larger size, mainly because a smaller image source already contains less detail, and sizing it up won't increase the detail any, and may also reveal more of the defects.

If your source file has that low a resolution (320x240 for instance) then you are probably better of using half D1 resolution (352x480 NTSC) or even quarter D1 (352x240). You are correct that resizing will introduce quality loss, but it is either that or encode with borders.

TmpGenc's resize function is OK but not the best, you can do better quality wise with virtualdub or avisynth, then frameserve to whatever encoder you prefer.

[hadenp]

OK bugster, jbodin...I'm taking all this in.

My interpretation of what you've said is:

1) One can't determine aspect ratio by simply dividing width by height. But that begs the question, what are the factors that detemine aspect ratio ?

2) Given that my source is 512x384 and that I want to author a DVD, I should try tmpGEnc (or Virtualdub + avisynth) and either scale it up to 720x480 (for NTSC - expecting that there may be some loss of quality)

OR

I could make a SVCD, ( using Nero? ) for which an MPEG-2 of 352x240 would look like 4:3 even though PowerDVD makes it look like it's taller than it is wide.

Am I interpreting correctly, kimosabes? Thanks again.

[jbodin]

I could make a SVCD, ( using Nero? ) for which an MPEG-2 of 352x240 would look like 4:3 even though PowerDVD makes it look like it's taller than it is wide.

Am I interpreting correctly, kimosabes? Thanks again.

I can't speak to the first half because I have no experience with burning DVDs (or DVD-compatible captures), but you're spot-on about the SVCD a 352 x 240 resolution capture resulting in a correct 4:3 aspect ratio on a standard NTSC television. This is exactly what I'm doing, except I'm capturing MPEG-1 files for VCDs.

One word of caution, though -- the resolution you've specified (352 x 240) is a VCD-compliant (MPEG-1) resolution; if you want to do an SVCD you will need to move to a 480 x 480 resolution (MPEG-2). If you do a MPEG-2 capture at 352 x 240, it won't be either VCD or SVCD compliant, and I'm not sure if you could view the result using standard set-top DVD players.

I recommend you review the VCD and SVCD standards here:

https://www.videohelp.com/vcd

https://www.videohelp.com/svcd

[bugster]

One word of caution, though -- the resolution you've specified (352 x 240) is a VCD-compliant (MPEG-1) resolution; if you want to do an SVCD you will need to move to a 480 x 480 resolution (MPEG-2). If you do a MPEG-2 capture at 352 x 240, it won't be either VCD or SVCD compliant, and I'm not sure if you could view the result using standard set-top DVD players.

I recommend you review the VCD and SVCD standards here:

https://www.videohelp.com/vcd

https://www.videohelp.com/svcd

352x480 is the half D1 standard for DVD. So it is often the reccomended resolution for longer, lower bitrated DVD's. 352x240 is also DVD compliant and is obviously lower quality, but allows you to get away with even lower bitrates.

[hadenp]

Thanks so much for taking the time to respond, check my responses and follow up! Armed with the info you've and tools you've suggested, I'm going to do some experimentation.

I still am pretty much in the dark about what determines aspect ratio ( is this too simple? am I missing something?) so if you can suggest any tutorial or guide - I'd appreciate it.

[bugster]

You could try getting your head round this guide.

[jbodin]

One word of caution, though -- the resolution you've specified (352 x 240) is a VCD-compliant (MPEG-1) resolution; if you want to do an SVCD you will need to move to a 480 x 480 resolution (MPEG-2). If you do a MPEG-2 capture at 352 x 240, it won't be either VCD or SVCD compliant, and I'm not sure if you could view the result using standard set-top DVD players.

I recommend you review the VCD and SVCD standards here:

https://www.videohelp.com/vcd

https://www.videohelp.com/svcd

352x480 is the half D1 standard for DVD. So it is often the reccomended resolution for longer, lower bitrated DVD's. 352x240 is also DVD compliant and is obviously lower quality, but allows you to get away with even lower bitrates.

Cool info, Bugster -- thanks!