svcd with future compliance: 352x576 vs 720x576

[baker]

As some may know I was telling everybody to use 352x576 for their svcd as this would make them future dvd compliant.

Well I just got a message from a guy:
i burn my svcd with 720x576 this is dvd standard and 50 minutes encoded with cce 2,5 will look great (dc precision 9)why should i use half resolution

Now I know this is really just mini dvd but he is right! Why are we using 2cds for substandard quailty when dvd quailty is just another cd away!

Future compliance and all!!!

But I have one question:
My dvd drive is down for a while so I need someone to see how the quailty looks on a FULLSCREEN movie not a widescreen as it neeeds less bitrate.

So here your mission:
Find a 120min film with lots of action (Matrix maybe?) Use a bitrate calcualator and work out the bitrate for 3cds. Do a 1PASS +VAF using cce frameserved from dvd2avi.
So thats simple enough, who can undertake the mission?

Baker

[baker]

One more thing.

80min cds will be used.

I just used a bitrate calc and for a 120min film a dvd has a bitrate of around 5000 while on 3 cds a svcd would only have a bitrate of 2600!!!

CCE is good but is it this good with only 1pass + vaf and such a low bitrate?

Baker

[baker]

Sorry something else!

Filters are not permitted EXCEPT the use of temporal smoother at 2 no more,no less.

This is used to fix the dvd and may not be used on the final svcd.

+ the audio can be done with another tool if you wish.

Baker

[baker]

Just relised that the avg bitrate will also have to be the max as 2600 is the svcd max bitrate anyway!!!

Baker

[scissors]

hi baker.

Did a test today. Used my tmpeg template and set res to 352 audio to 48.

SpruceDVD accepted and authored entire film into 580Mb vob.

nero made miniDVD.

Played okay in windvd, not standalone (due to media incompatiblity)

The point - you asked why not go full d1 instead of 1/2 - how about fitting all aliens films on one dvdr, or all starwars....

[adam]

There are two reasons not to use this resolution.

#1. You aren't guaranteed compliance until you re-author your mpg as a dvd. Your current disk will be an xsvcd and will not be guaranteed to play on all svcd compatible dvd players, while the half d1 cvd is guaranteed compatibility on all svcd compliant hardware players.

#2. If you stay within the bitrate limitations of svcd than you have drastically cut down on the amount of bits per pixel you get. Even with an avg of 2.6mbits and a much higher max (non-compliant), this is still not enough bitrate to support resolutions this high. Even on 3 cds you will still probably have less bits per pixel than a 2 cd svcd, and certainly less than a 2 cd CVD.

A widescreen 23.976fps CVD with an avg bitrate of 2mbits actually comes very close to the bits per pixel ratio that a dvd gets. Unless you use a very high bitrate than a half D1 resolution will be much higher quality than a full D1 resolution. Its questionable whether you would even be able to use a high enough bitrate due to the hardwares inability to read cdr media that fast, but if you did then one this is for sure is that it will take more than 3cds.

[baker]

Well has anybody tried my idea yet?

Baker

[adam]

I need someone to see how the quailty looks on a FULLSCREEN movie not a widescreen as it neeeds less bitrate.

I have experimented with full D1 resolution and even with widescreen movies I am not satisfied with the quality. At least not enough to use it over 480x480 or 352x480. I think a fullscreen movie at these settings would surely have a great deal of artifacts.

But the question you asking is one of the oldest debates in mpeg encoding. If bitrates remain constant, higher resolutions result in sharper picture but you lose detail and have increased artifacts. Which is preferable? Its totally subjective so the only way for you to truly get an answer is to test it yourself.

[baker]

Thanks for the reply sefy,

So really a cvd will actually look better than a 3cd dvd as it will have more detail per macroblock?

If this is true than I will get results like dvd with my current results anyway?

You see I was thinking their lately and was really worried about future compatibility. But since you, sefy, know a good bit about mpeg technology I will take your word for it and stick to 352x576. May be not crstal clear but 3-4 movies per dvd when I go to convert my collection to do will do me anyway!

Just to get this completely right I will have to use the following settings:

video: mpeg 2 500-2500 bps
audio: mpeg ?? 160 bps
and a res of 352x576.

so in future i will just have to take the 2mpegs off the cds and join and author them.

No new encoding needed right?

Baker

[Sefy]

baker, why are you using my name ? it was Adam who replied, not me.

[baker]

Sorry sefy!!!! I dont know how I made that mistake!!

Also have you guys got something that tells you when your name has been used here?

If open A topic and put sefy in it you just appear!!!

baker

[Sefy]

Not that I know off, I simply search the forums for people who specificly ask for my assistance.

[adam]

Maybe the forum is just messed up and I can't see Sefy's reply but I assume you were talking to me baker?

Like I said its a pretty subjective matter but it does say alot to analyze it mathmatically.

352x480x29.97=5063731.2 pixels per sec
480x480x29.97=6905088 pixels per sec
720x480x29.97=10357632 pixels per sec

You can check my math if you want to but by my calculations half D1 resolution (CVD) has %26.77 less total pixels than 480x480 (SVCD), and %51.77 less pixels than full D1 (DVD.)

Now the bitrates used on dvd varies but lets assume that the typical dvd uses an avg bitrate of 5mbits per sec, which probably isn't too far off. Well CVD has less than half as many pixels as dvd so you only need half as much bitrate. So you see, at 2.5 Mbits a CVD comes VERY close to matching the bits per pixel ratio that DVDS achieve.

At svcd resolutions (480x480) you would need more like 3.3mbits to achieve this same level of bits per pixel.

Now look at a full D1 xSVCD encoded at 2.6mbits... In terms of bits per pixel this would be equivalent to a CVD encoded at ~1.27mbits.

So you see, using 720x480 instead of 352x480 cuts your bits per pixel by more than half. I personally feel that this is too much bitrate to throw away in order to have a sharper picture.

As far as future dvd compatibility, I really don't have much experience in this area but I'm pretty certain that the only further transcoding you would need would be to resample your audio to 48kHz if you originally downsampled to 44100kHz. You will also have to remultiplex your mpg as a dvd.