how noticeable of a difference in TMPGEnc

[jyeh74]

Most of my mpeg-2 files are 352x240, a few files are a little bigger (like 480x480). When I convert these files into dvd-compliant files, I can choose either 352x240 or 352x480. If I choose 352x480, will it make much of a difference in terms of quality? I know the bigger files will look worse since I am choosing a lower resolution, but will the smaller files (352x240) look worse since I am converting to a better resolution file (352x480)?

[jyeh74]

Original file = 352x240 convert to 352x480 ---> better quality since you are going to more pixels?

[redwudz]

Well, you won't get any improvement by re-encoding to a larger framesize. If your files are 352x240, leave them alone if they are DVD compliant. The 1/2 D1 format is most useful when you have a long file and you need to encode at a lower bitrate to fit to your media.

[jyeh74]

So you're saying if my original file is 352x240 pixel, and i convert it to 720x480 pixel, it wont make any difference? Someone told me that if I convert from a smaller resolution to a bigger one, it will LOOK CRAPPIER.

my only choices are:
720x480
704x480
352x480
352x240

most of my files are 352x240 and some are a little bigger. I'm trying to find a happy medium.
sorry, what is 1/2 D1?

[Scorpion King]

352x240 is dvd-compliant so they don't need resized.

As for those 480x480 files..... I think with either resize (down to 352 or up to 704) you are going to take a quality hit. I assume those 480x480 are 2.5Kbps SVCD files. You are going to need to use quite a bit more bitrate than that even with the 352 resize if you expect to maintain the quality level you have now. At least that is my opinion anyway.

Good luck.

[jyeh74]

so with the 480x480, is it better to convert to a higher 720x480 or a lower 352x480? I'm not sure I understand what happens when u upconvert versus when u downconvert.

[Scorpion King]

so your saying if my original file is 352x240 pixel, and i convert it to 720x480 pixel, it wont make any difference? Someone told me that if I convert from a smaller resolution to a bigger one, it will LOOK CRAPPIER.

sorry, what is 1/2 D1?

Lets say you have a super high quality uncompressed AVI file that is really clean (no noise, blocking, compression artifacts, etc) and you encode it to 352x240 mpeg2 with 1.8Kbps bitrate. This encode is going to introduce compression artifacts, noise, blocking, etc into your video file. The high quality is now lost never to return.

You later do a simple reencode on this low quality file and you find that you must use a lot more bitrate than the file was using because the encoder now must try to compress and store all the compression artifacts, noise, blocking, etc that is now in the video file from the first encode, besides trying to store the video. Throw into the mix a resize-up and you will need to again raise the bitrate to try and store (retain) the damage done by the resizing.

The noise and the crap adds complexity to the file making it not so easy to compress so more quality is lost making the use of a higher bitrate necessary. Or tsomething like that anyway. lol

1/2 D = 352x480

Hope this helps
Good luck.

[ntscuser]

so with the 480x480, is it better to convert to a higher 720x480 or a lower 352x480? I'm not sure I understand what happens when u upconvert versus when u downconvert.

Higher (720x480). You will not get any increase in resolution but you will at least preserve the resolution you have now.

[jyeh74]

so with the 480x480, is it better to convert to a higher 720x480 or a lower 352x480? I'm not sure I understand what happens when u upconvert versus when u downconvert.

Higher (720x480). You will not get any increase in resolution but you will at least preserve the resolution you have now.

So lets just say my file is 352x240. The two cases below would give me identical results in terms of quality?

1) convert to 352x240 dvd-compliant
2) convert to 720x480 dvd-compliant

Then why would TMPGEnc give you a choice of :
720x480
704x480
352x480
352x240

When you can just select 720x480 and not lose any quality (since most mpegs that I have are lower than that anyways)

[vico1]

Or instead of re-encoding, keep your compliant vids the way they are as was stated, and
use DVDPatcher on your non-compliant ones, then author...after that, put them (the vob's)
back to their original rez (again with DVDPatcher)...then burn.
(I would "back-up" the original non compliant ones before patching, in case of a screw-up...it happens)
Remember tho...audio has to be 48kHz on Mpeg2. (to be dvd compliant)

Worked for me in the past.

[guns1inger]

So lets just say my file is 352x240. The two cases below would give me identical results in terms of quality?

1) convert to 352x240 dvd-compliant
2) convert to 720x480 dvd-compliant

Then why would TMPGEnc give you a choice of :
720x480
704x480
352x480
352x240

When you can just select 720x480 and not lose any quality (since most mpegs that I have are lower than that anyways)

Tmpgenc gives you the option of these resolutions because they are DVD compliant NTSC resolutions. What you chose to do with them is up to you.

In answer to your question, if you have 352 x 240 source, a simple encode at the same resolution will give you better image quality (all else being equal) than resizing up to 720 x 480. Either way it will be resize to 720 x 480 at playback, but generally hardware will do it better than software, and as you buy better players, the hardware will continue to improve. If you resize up you lock all the flaws into your encode. Also, you will have to encode at 4 x 5 times the bitrate to maintain the image quality, resulting in a file size 4 - 5 times as large. This may or may not be a consideration.

Things are not as clear cut when you have 480 x 480 source, but my inclination would be to resize to a 704 x 480 frame, with the actual image resize to 528 x 480 (tmpgenc will do this for you) so you preserve all your image, rather than throw a third of your pixels away.

[thecoalman]

Higher (720x480). You will not get any increase in resolution but you will at least preserve the resolution you have now.

You may also introduce artifacts scaling up....with 480x480 you have a choice between one of two evils. Either scaling down and losing some resolution or scaling up and introducing artifacts and in fact making it look worse IMO.

Best thing to do is make some test clips and decide what suits you.

FYI, 480x480 is SVCD compliant. If your DVD player supports it you can author a SVCD and not have to do anything to it

[guns1inger]

With 480 x 480 it is only a small horizontal resize, and unlikely to do much damage.

[mats.hogberg]

I'd run those 480x480 files thru svcd2dvdmpg, and author "as is". Chances are very good they will play without problem. (svcd2dvdmpg is used to trick the authoring app into accepting the mpg as a valid DVD source.) That way, you'd avoid the quality degradation inevitable in every reencoding.

/Mats

[jyeh74]

ok, so everyone is saying if I pick a higher resolution, I will contaminate it with "artifacts". I dont get how so? If my file is 352x240 and I choose 720x480, doesnt it have much more room to play with?


If I pick a lower resolution, it will obviously look shitty. If I stay with the same 352x240, it might look a little worse because compression artifacts, noise, blocking need to be accounted for.

[guns1inger]

Without a lot of work it will never look much better than it does. You simply do not have enough data to work with. Your best results will come from leaving it as-is, and letting the hardware do the work for you. A higher resolution only helps you if you have good enough source. Your source is only one quarter that resolution.

[Scorpion King]

Most of my mpeg-2 files are 352x240

352x240 mpeg2 is DVD-Compliant file types. These don't need converted. They will author and play as is, unless you encoded them with a nonstandard framerate or GOP structure.

Read this ---> What is DVD? Make sure you use the settings for NTSC.

Resizing those 352x240 files up will not gain you anything but less time on a DVD disk because you will need to use a greater bitrate just to try and retain the quality the files have now, making the up-resize not worthwhile. The information is just not there anymore, it was thrown out during the first encode, and you cannot now recreate it. Filtering might be able to smooth out some of the artifacts, etc, but they cannot create the detail. The detail the video once had is gone and no resizing/reencoding is going to bring it back..... The deal now is to not loose anymore.

As for those 480x480 files you really only have 2 choices. You can 'try' changing the header (as stated above) and author them as is, then see if your DVD player will play these non-standard files. The other method is to resize-up to 704 or 720. When you do that you will need to find the proper bitrate (by trial and error) that will retain as much quality as possible. If your files are SVCD compliant then the present bitrate is around 2.5Mbps. If so then I would try around 6Mbps VBR with those 704x480 versions. I don't know what the magic number will be, it may even be higher..... That is going to depend on what the quality of the files are now (how much noise, blocking, etc). The more crap then the more bitrate you are going to need. With 6Mbps VBR you are going to get around 100minutes or so of video on a DVD blank using 224Kbps audio.

You need to run a few tests, then you will know for sure what to do. lol

Good luck.

[jyeh74]

my bitrate is consistently 1100-1300 since I am maxing out the videos on a dvd-r at around 6.5 hrs length. That bitrate is ok, since the quality isnt that great anyways.

If bitrate is for quality, then whats the resolution for? I thought quality also.

[ZippyP.]

If bitrate is for quality, then whats the resolution for? I thought quality also.

Higher resolution requires a higher bitrate to keep quality. More pixels require more bits, it's that simple. If you "bit starve" an mpeg you will get blockiness and objectionable artifacts. Higher resolution will give you a sharper picture, something that you cannot just "create" from a low resolution source. In general upscaling will reduce quality and not improve it, how much depends on how much you upscale and how discerning an eye you have.

[guns1inger]

Bitrate is simply for data storage. There is a correlation - to low and you don't have enough data to maintain quality, which is where artifacts come in. resolution is also part of the equation. What you seem to be unable to comprehend though is that you (or whoever created these videos you have) have undertaken an extremely lossy process. The simple act of resizing down to such a low resolution has immediately thrown away 75% of your video data. Even if they had maintained a very high bitrate or use a lossless codec, 75% of your data is gone. But they didn't use a lossless codec or a high bitrate. They used a low bitrate. Between 30 and 50% of the remain data was thrown away through compressing the remain video. So you know have a video which has roughly 12% of the data of the original video, give or take. Data which you can never get back.

You can resize this image to HD resolution if you want - the software is easily available. Hell, if 720 x 480 is better than 352 x 240, then sure 1920 x 1080 must be that much better again. Except that you barely have enough data to create a moderate quality image at 352 x 240. You have nowhere near enough data to fill a 720 x 480 image with anything but blurry, artifact ridden image. The damage is done.

The best you can hope for is to maintain what you have with no further degradation. If it is already DVD compliant, upsample the audio and author with what you have. For the 352 x 240 material that is the best you can reasonably do.

The 480 x 480 material does present you with options, but even then, a good part of the image data has been excised, so you still have damaged goods. For this material I would do some tests at 704 x 480 (image resolution 528 x 480 pillarboxed) and see how it looks. However you will need a suitably higher bitrate for the higher resolution in order to maintain the quality you have. If you can author a non-standard disc and have it play using the material you have, again you will be better off.

The basic tenet of video is a simple one. Garbage in, garbage out. Like it or not, you can't polish a turd. The best you can do is spray it gold and hope no-one notices.

[ultramarine]

Correct me if i am wrong ....

352x480 supports progressive scan so it is better than 352x240 when changing the 480x480 to dvd compliant spec with tmpg.

I won't redo the 352x240 though. Once data is lost, stretch it won't improve quality.

[thecoalman]

If bitrate is for quality, then whats the resolution for? I thought quality also.

Just to add, they can both affect the quailty. The issue you have is the resolution is already gone, to quote guns1inger:

Data which you can never get back.

Here is an explanation using images, these are not from video but the same principals apply you start with a 720x480 image (meet headbot :P ):


You scale it down and lose resolution:


You scale it back up:


The software has to "guess" what belongs there. How well it works depends on the software you are using. Some methods work better than others. On the image side of things there is a few applications that will examine the image and attempt to find the edges and fill the solid areas which will give you better results that you see above but that will only preserve edges, it won't replace what was in the original image. There was a video filter that worked in similar fashion mentioned in the News forum not too long ago.

The bitrate is dependant on the resolution, too little and you introduce artifacts. Use too much and you're just creating a larger file but it certainly won't affect the quality of the file. Again some images,

Taking the image above (9KB):


Compressing it to about (3KB), this would be the equivalent of reducing the bitrate on a video:

[guns1inger]

To take it to the next step, here is your image reduced in resolution and bitrate to approx what you have now, then resized back to 720 x 480.

Notice how adding the extra resolution doesn't add quality, and in fact makes the flaws in the original even more pronounced

[AlanHK]

ok, so everyone is saying if I pick a higher resolution, I will contaminate it with "artifacts".

In general yes.

But I was playing with some cartoons encoded at about that resolution. I left them at that size when making MPEG, just added some borders to make the size a correct DVD resolution, and the images were quite jaggy on the TV screen. These artifacts were in the original encode, not created by my conversion; but they were far more visible on TV than on the computer monitor.

So I tried doing a resize to 720x480 in an avisynth script. That gave smoother lines and fewer jaggies.

But for normal live action, probably it would not be an improvement.

If you want to try, though, there are many filters for sharpening and smoothing that possibly will give a better result than simple scaling.

[thecoalman]

But I was playing with some cartoons

Cartoons would be an exception. Your only concern is preserving the edges. Image software specifically for scaling images up works exceptionally well with cartoons. Some of the samples I've seen looked as if they were originals and appeared as if they could be scaled to an infinite amount. The difference is you already have well defined lines filled with solid colors.

If you give me a simple cartoon image using the magic wand I could convert it to a vector based graphic in a few minutes and it could be scaled infinitely... The problem with video is you need something that will do it automatically, as I mentioed ther was a scaling filter posted in the News forum not too long ago, haven't tried it myself.

[jyeh74]

Wow, thanks everyone for the education. I shoulda just left my 352x240 the same instead of converting it to 352x480. I had no idea 352x240 was already dvd-compliant. I just followed Redwudz advice of keeping it 1/2 D = 352x480 format. But why would you want to stretch the already dvd-compliant out to 352x480?


What about my 352x288 and 384x288? I think these are better suitable at 352x480 or 352x240 (assuming all low bitrate at about 1200)??

[jyeh74]

Correct me if i am wrong ....

352x480 supports progressive scan so it is better than 352x240 when changing the 480x480 to dvd compliant spec with tmpg.

I won't redo the 352x240 though. Once data is lost, stretch it won't improve quality.

Redwudz and scorpion king told me to keep 1/2 D1 format, which is 352x480, even though most of my files are 352x240. I'm a little confused too? What do I do with my 384x288 and 352x288?

[jyeh74]

for my 352x240 files, the audio is 44100 Hz, will TDA automatically convert them for me?

I tried adding these already dvd-compliant files into TDA, but for some of them it says "the video GOP is too long" The NTSC system is limited to 36 fields (18 frames) I have no idea what this means. Does it mean for these files I have to run them through TMPGEnc anyways?

[Scorpion King]

Redwudz and scorpion king told me to keep 1/2 D1 format, which is 352x480, even though most of my files are 352x240.

Wooo now Charlie, I didn't tell you that. You better read this page again and get 'unconfussed'.... I told you to leave those 352x240 files alone. You're the one thats itching to do some resizing no matter how hard anyone tries to talk sense into you. Don't start making crap up now. You hear....

[j4gg3rr]

I think its better to resize with AVISynth on a PC than it is allow your DVD Player to resize Half D1 resolutions. Make everything standard 720x480.