yes i am stupid

[12twelve12]

please bare with me, i'm about to ask a really dumb question regarding resolution. what exactly is resolution and what do the numbers mean in, say, 720x480?

[SLK001]

This is the horizontal size (720) and vertical size (480) in pixels of the original digitized video stream. The higher the resolution, the higher the detail that will be shown on a TV. For a DVD, 720x480 (NTSC) is the maximum resolution available, which is basically 4 times the resolution of a VCD.

[12twelve12]

can you create a vcd that is 720x480, or can a vcd only look so good?
another thing, how do you know what will fit on your tv screen?

thanks

[tmcmvd]

Anything will fit, if made by certain rules...

Your TV is made for the max resolution the standard (NTSC,PAL, or SECAM) supports. See the What is to the upper left for more details.

Yes, one can create a VCD with a higher resolution than the standard, it's called a X-VCD. There is also SVCD, X-SVCD and CVD...and a lot in between. You will have to do a lot of reading on this page to get the hang of it. Just begin on the upper left and read the newbie guides.

Good luck.

[12twelve12]

i guess what is confusing me is...

i thought the numbers represented the size (dimension) of the video. but when i played a 352x240 on tv, it was full screen whereas i expected it to be a little rectangle in the middle of the screen. and i don't understand why you have resolution option when capturing video when it seems like you could just capture it as it is. i've been all over this site, but have found nothing (or not enough) of this to clear it up. maybe someone knows where i can learn more about it.

[drewson99]

if the settings are 4:3, it will fill the screen, but the pixels will be bigger. like with a digital photo, with a set resolution, the bigger you blow it up, the more pixelated it gets.

[12twelve12]

thanks drewson99, but i am still hoping someone will shed even more light on this. or at least tell me where i can read about resolution and aspect ratios.

[liquid217]

here is a good example. the computer where you are sitting now can have its resolution resized. Mine at the moment is 1024x768. Now all i have to do is goto display properties, and drop it down to 640x480 and it should be in a litlle box on my screen right? Nope, darn computer just resized everything for me. This is the same way with video being played back on a tv. If the regular resolution is 4:3 (352x240 720x480) then its just expanded to fit full screen, just like yout video card does on your computer.

although there is a lot of technical jargon, this would make for some good reading for you
http://forum.vcdhelp.com/userguides/94382.php

[bugster]

I believe I am correct in adding here that pixels on a computer screen are square, so a video with a resolution of 720 * 480 will use that much screen space when played, unless the player does some interpolation (or something!?!) to play the video at the correct aspect ratio. (Try playing a 480*480 SVCD in WMP, then again in Power DVD to see what I mean). TV Pixels are NOT square, and can be streched horizontally, though the nuber of lines vertically is fixed by the TV standard.

At least thats my understanding of things!

[liquid217]

yes very true, but i only meant the illustration as an analogy, not as a complete comparison to computer vs video resolutions. pixel size can play a large part in video. Something i love to hear all the time is "whats's wrong with this svcd i made? its all squished!" Of course, svcd's use rectangle pixels (480x480), but when played back in a dvd player, the dvd player will resize the svcd for full screen playback

[12twelve12]

thanks guys, and that brings me to more questions

ntsc standard is 352x240 correct? and 720x480 is basically twice the size, how come these don't reduce to exactly 4:3? or is 4:3 just an approximation? and i read of capturing at 352x480 for ntsc. what is that? wouldn't that be an odd shaped video? i know i didn't word this as clear as it should be, but if you can see where i'm lost, try to explain.

many thanks

[liquid217]

4:3 is really more of just saying that it is to be played at full screen, (as opposed to 16:9, which is widescreen). All vcd, svcd, and cvd resolutions are for fullscreen format
assuming you are using ntsc
vcd = 352x240
svcd =480x480
cvd = 352x480

all of these formats are 4:3...they are RESIZED when they are played back (at least on the tv they will be, sometimes software on the pc isn't bright enough to figure this out). Yes some of these resolutions seem rather strange, but they are 4:3....they are stretched back to the correct screen size. the official ntsc resolution is D1 (720x480), ironically, this is also dvd resolution. this is also a 4:3 resolution.

[liquid217]

again, as i said before, satstorm's guide is worth taking a look at

http://forum.vcdhelp.com/userguides/94382.php

[Nelson37]

12twelve12 - Your problem lies in assuming that 352x480 describes the size of the video ON THE TV, which it does not. The TV will take any compatible video stream and fill the screen with it. Now, since the TV is displaying an apparent 720x480 picture, it has to stretch whatever the original resolution was to reach 720x480. The higher the res you start with, the less stretching occurs. Since in most cases the original source was 720x480, which has been captured at, or resized to, 480x480 or 352x480, we have lost or thrown away some amount of image to get to the lower resolution. When upsized to 720x480, this lost info can be more visible.

To further confuse the issue, due to some intricacies of the human eye and the TV transmission system which I do not fully understand, the vertical dimenstion is much more important. Put another way, 352x480 is better than 720x240, even though both are capturing 50% of the image.
Capturing 720x480 would be ideal but is usually too large a stream to deal with.

The more important, related issue is bitrate. Lower resolution requires less bitrate to display accurately. Bitrate (NOT resolution) determines filesize. A 480x480 video with too low a bitrate will look terrible IN MOTION SCENES (still shots may look good), while a 352x240 video with an even lower bitrate may look great, although a careful look at details will reveal a lower quality image.

There are several concepts involved which are hard to get a handle on, such as that analog video does not have a resolution, only an apparent one by which we can digitally describe it.

[tmcmvd]

Don't forget that you are watching a anologue tv. This TV picture is built up by horizontal lines. Being written from left to right, line by line with 60 times the whole screen per second, hence the 30 frames per second used by NTSC.

First even lines are projected, then odd lines... due to the speed of refreshing it seems like one high res picture of 30 frames per second.

Look at is as a photograph. When u take a negative, it can be magnified to any size, the bigger the size, the smaller the detail.

Normal 36mm negatives are used for home purposes, for large advertising bill boards larger negatives are used like 6x6 cm becourse otherwise you would get no detail when enlarging to 4 x 6 metres.

Now when u use a highres film for your camera, like a dia-positive, it can be projected X x X metres and still have a lot of detail.

This is like the digital videofile... The higher the resolution the higher the detail when projected on the screen of your TV. When you watch a program on a small TV it always looks great, the larger the TV, the larger the magnification, the lower the detail. On the computer you can point at any pixel like on a chessboard, but on a screen this is not possible (except for a digital TFT LCD screen)

So the TV sees the boundaries of the analogue video signal and displays almost the full immage to the whole screen, independent of the resolution. A VHS recorder normally only displays half the lines, so the quality is worse.

The digital to analogue chip (your video cpu in the PC, or the MPEG processor in a DVD player) convert to analogue signal for TV.

This signal is standarized, so the TV will always display fullscreen.

When the aspect ratio differs too much from the 4:3 norm the picture may display distorted, so heads will look like eggs or baseballs.

Hope this helps a little of understanding.

Let me know if you have more questions.

[tmcmvd]

To clarify the compression method in simple words, try vizualising the follwing.

If I have 24 bit of information, used to produce one pixel in (a for the eye) one color and have 700 pixels of this on a line and i would like to make this smaller I would have too descard some information.

Like 0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0 is larger then 24x0, the first takes more space, though it says the same. When compressing (in general..details is too difficult to explain here) the codec puts the pixels with the same color next to eachother and makes is 4xblue 3 xred instead of blue red red blue blue blue red. (This is a very simplistic way of looking at things !)

Next to this it can take 5 different colors of blue who lay very close to eachother and exchange them with one color. Mutch like the JPEG picture compression. The more space, in bits you have to spare for info, the less info has to be thrown away the better the picture. Naturally the less bits available, the lower the quality the lower the filesize.

If you split the resolution in half, the picture quality will degrade due to the loss of detail, but will also take less space.

Maybe this cleared things up a little more. If you want you could study MPEG compression in detail, but you won't find it here.

Greetz,

Mike.

[12twelve12]

ok i'm going to try to get it right...

i was thinking 720x480 was kind of like the demension of the video. but that can't be right because it is the equivalent to 3:2, which i imagine would look distorted when displayed 4:3(still assuming 720x480 was the demension of the vid). so i guess 720x480 is the amount of horizontal and vertical information. so then, when playing a video in wmp, what determines the dimensions of it. how are some square? i don't have a 480x480 video to look at. are they square on wmp then distorted on a tv?

i'm sorry i'm so slow on absorbing all of this, and appreciate very much the time you guys have taken to help explain it. sometimes i just feel like i have to know how something works, and right now this is it.

12twelve12

[kinneera]

It might help you to know that there is a field in the header of an MPEG file generally referred to as the Display Aspect Ratio (DAR). This tells a fully compliant MPEG decoder the aspect ratio that the video is intended to be displayed as. The resolution will then independently affect only how much detail is actually encoded into the video - it has no effect on the display dimensions.

Since you seem to be curious about computer display as well, what you need to know is that some software programs respect the DAR, and some don't. Software DVD players such as WinDVD and PowerDVD do size the video based on the DAR. The last time I checked, however, WMP takes the resolution literally, which means that SVCDs and CVDs (352x480) in particular will look distorted. It all depends on what you're using.

[12twelve12]

i'm not as stupid now, but still things are hazy. more details please, especially on my post before this one.

[thxkid]

well once you get this down, just remember that not all DVD players will play past the standard VCD, SVCD or DVD resolutions, while one DVD player brand will play a VCD at 1150 Bitrate at 352x240 and then lock up or not even reconizie a XVCD you did at 720x480 at 4000 bitrate, while another DVD player brand will play it no problem, yeah have fun looking for a player that plays anything past standard VCD and SVCD's. Another reason this is a good forum, plenty of people have all kinds of DVD Players and can give advice on what ones will play and not play certain formats or tweaks past the standard formats.
Most of the people on this forum that has the advance knowledge on this subject have been doing it for a lOOONNG time and have lenty of trial and errors to find out what works and then take that and tweak it even more.
With my 2-3 years of messing around with VCD and later SVCD, its try try try again until you get it right and then try again to tweak it even to push it further. Most here will tell you the 1st stuff they did you go back and laugh at what you turned out compared to today.
I can't belive the crap I did 3 years ago and at that time thought, wow cool. But through reading and trial and error (CD-RW's are great for this) you can improve what you do as you try more and more using your software tools to capture and encode with. Don't look at it as a challenge, but having fun with it, I find that more enjoyable.

[12twelve12]

if i capture a an avi at 480x480, will it be square?

[kinneera]

Yes. But if you encode it to an MPEG with a display aspect ratio of 4:3, that is how it will be displayed.

[DonnaJ]

Thank you.

I've read the guides, the what is's and whatever else I could find. These explanations are easily understood and have made it clearer for me.

DJ

[12twelve12]

will it then be distorted, or just better vertical quality than horizontal?

[kinneera]

If the aspect ratio of the source video is 4:3, when it is captured in AVI format at 480x480 it will then appear distorted. Once encoded into MPEG at 4:3, it will be stretched back out and will look correct. It will have less horizontal detail than a capture at 640x480 or 720x480, but should still look pretty good.

[fmctm1sw]

If the aspect ratio of the source video is 4:3, when it is captured in AVI format at 480x480 it will then appear distorted. Once encoded into MPEG at 4:3, it will be stretched back out and will look correct. It will have less horizontal detail than a capture at 640x480 or 720x480, but should still look pretty good.

I am struggling with this too. I capture with vdub at 400x480 using huffyuv. When I encode to vcd, it looks exactly on my tv like it does on my computer (stretched from top to bottom/smashed in on the left ad right side). How do I stop this? I covert with tmpg using all the default vcd setings. Do I change the source aspect ratio to 4:3 NTSC or change the video aspect ratio somehow?

[vitualis]

http://www.vcdimager.org/guides/mpeg_still_images.html#aspect_ratio

Regards.

[kinneera]

Do I change the source aspect ratio to 4:3 NTSC or change the video aspect ratio somehow?

Yes, this is exactly what you need to do. I forgot to mention that, sorry. The source and output aspect ratio should be set to match what the video is supposed to be under these circumstances.