New Idea: SVCD at 720x576

[astragalos]

Hello everybody:

I have read a lot in the last days about CVD and its possibilities for making a DVD compliant mpeg2 in the future,as it is a half D1 DVD resolution. So I began making various tests with dvd2svcd at that resolutions and I found it was not bad, but not good enough either. So I thought that it could be possible that my dvd player could even play svcd at more different resolutions, and I did so.
I decided to make a mpeg2 file with 720x576 resolution, that is the D1 DVD resolution and I put it on a SVCD and the result was excellent, as I thought. The resulting file was not bigger than one in 480x576, so I thought it could be better for the future if I merge then all the mpeg2 parts of a movie into one DVD-R. That's only thinking in the future because I find that DVD-RW units are too expensive by now. I don't know if I follow the correct way thinking in the future but I would appreciate any of your comments.:confused:

[gizmau]

first: this idea is not new, its only some kind of xsvcd (=off-standard svcd).

its better to use 704x576 instead, because this resolution is not only div16, but div32 as well!
the pixelform is the same as at 720x576 and its allowed by the norm for dvd, too.

btw: the file size keeps allways at the same size when the bitrate is the same - no matter which resolution used...

[waldok]

HI,

THat was my point. Will this 720 (or 704) x 576 stream be directly compatible for future DVD authoring when dvd writers become cheaper).

I did this XSVCD at 720x576 (or 480 for NTSC) twice now, and quality is near perfect. Could hardly tell the difference with the original DVD.

If the encoded mpeg2 streams can be reused "as is" for burning on a DVD-R (through the appropriate authoring program), well, I guess this would be heaven !

Waldok

[gizmau]

it depends on the dvd-authoring-program. many (most?) tools dont allow a gop length larger than 12 (PAL) or 15 (NTSC).

[adam]

Well as far as future compatibility with dvd is concerned, then sure 720x480 makes sense but as far as quality is concerned I'm not as convinced. You didn't mention what kind of bitrates you were using but since you title the thread "SVCD at 720x576" I assume you are using bitrates under 2.6Mbits.

If this is the case than, in my mind, CVD's half D1 resolution makes perfect sense. A typical dvd is probably encoded with an avg bitrate of around 5-6Mbits per sec. CVD has exactly half the resolution of full D1 dvd so it only needs half the bitrate to achieve the same bits per pixel, which is really the most important thing when it comes to quality. At ~2.6mbits and 352x480 you are coming very close to this optimum level of bits per pixel that is dictated by your source. At 480x480 its pushing it but still not bad. But if you keep the resolution at 720x480 then you are literally getting half as many bits per pixel and you are actually getting closer to the bits per pixel level that vcds use. Sure with the higher resolution you get sharper picture and since quality is relative, this may actually be more appealing to some people.

As far as resolution is concerned, either full D1 or half D1 (CVD)provide dvd compliancy. As far as quality is concerned, CVD probably comes closer to actually matching the quality of the source dvd. Personally I can see lots of artifacts when I encode at 720x480 but almost none when I use 352x480. Just some food for thought. Have you actually given CVD a try? You may prefer it over full D1 resolution.

[waldok]

As I posted in another thread, I was very disappointed with CVD resolution since I could very clearly see aliasing on "near vertical" diagonal lines, which made the movie unwatchable (to my opinion).
Maybe you can help me on this since I guess the aliasing is due to interpolation from the 352 pixels per line to fulle width. Is there any particular setting that would attenuate this "stair effect" ?
You had a good point for 720x576, quality is not that great finally (contrarily to what I said before, nut probably the movie I tried was not representative). I would have liked to go to 352x576 fo rDVD compatibility, but since I'm not so pleased for the moment, I came back to "regular" 480x576.

I sure would appreciate if you (or someone else) could post your settings for producing great quality CVDs (352x576) from a PAL DVD (NTSC will be OK too). I can't believe so manty people find it great and I simply find it poor. I must have done something wrong.

THanks

Waldok:confused:

[Dreassica]

I have had some succes in increasing quality by increasing the max bitrate beyond the standard SVCD max, like 3000-3500 range.

[waldok]

But this will lead to too many CDs for one movie I guess...

THanks for your suggestion though

Waldok

[Dreassica]

If it does then i haven't noticed it. If the average bitrate is the same then it shouldn't matter too much, be sure to lower the min. bitrate too. But not too low of course. It worked for me with no noticeable difference in filesize yet/ It should mean that u will get more bitrate distributed to higher action scenes at the expense of lesser ones. U will have to see for yourself if it works on your source. Mine is Anime and it doesn't show too much. If i leave the max. bitrate at suggested number the high action scenes look really bad (lots of blocks) even at bitrates 2700 average, but when i increase max bitrate by 750 or so, the effect really shows!!

[waldok]

Well Dreassica, this sousn quite interesting and I'm going to give it a try tonight. I indeed have some blockyness in high motion scenes whereas slow motion scenes are perfect. This might help. I'll let you know.

Thanks for your help.

Waldok

[Kb_cruncher]

I am reletivly new to svcd encoding and have been battling with using cvd resolution as the aliasing(combing)effects that Waldok mentioned are a real killer.i have made a few posts on this issue with 0 replies to any of them,so until i can find a solution i will stick to full res as i really want DVD compliant files.Is there anyone out there that has any idea on how to at least lessen these effects? as i think cvd resolution is a far more sensible choice.I have tried everything i know without results but will keep trying and be sure to post anything positive.

[waldok]

Well KBcruncher,

I thought I was the only one in the world to notice this unacceptable aliasing effect with CVD.

Happy to see some other folk noticed it too...

Unfortunately, I don't really think there is a real cure considering that these stair effects are probably part of the 352 to full with interpolation.

I'll stick to SVCD from now on (except for capturing old S-VIdeo analog tapes which will probably be OK with Half-D1 resolution).

Anyway, I'd be mlore than interested if you (or anybody else) find a way to smoothen this stair effect.

Waldok.