Capture->Divx->DVD->Standalone?

[smoki]

Hi all,

i am thinking of dumping my old trusty Cyberhome CH402 standalone player for a unit that plays .avi (divx) as well...i want to capture from TV (PAL) then encode to Divx and play on the standalone..

Are there any space/quality advantages in using Divx over Mpeg2 when capturing from TV? Would i be able to compress say a 6000kbps mpeg2 capture to 1500-2000kbps Divx without compromising quality? The divx files would have to be burned as "files" in data mode, or can i author the whole thing with menus just like a normal mpeg2 Dvd?

Thanks.

[theDruid]

I've no experience of MPEG-4 DVD players (which can play DivX), but I'm pretty sure you'll just have to author the discs as data.

As for space/quality issues - it's going to be very subjective.

I personally doubt that a DivX which is maybe a quarter or a fifth the size of a DVD/MPEG-2 file will have 'equivalent' quality.

The DivX codec is intended to be used for much higher compression ratios than MPEG-2, but the more compression you have (in general) the more noticeable artifacts etc.. you're likely to have.

In theory, you could fit about 6 low quality DivX's on each DVD-R (going on a DVD-R being 4.5 gb, and each DivX being 700 mb - small enough to fit on one CD)... or 3 DivX's at high quality; where each DivX would be the size of 2 CD's.

That's where the advantage would be in terms of space - but don't expect a one CD DivX to be DVD quality - a lot of people seem to claim they are, but they are clearly not in terms of compression artifacts etc..

cheers,
mcdruid.

[smoki]

thanks for the reply...

well if you say that you should be able to fit 6 x 700MB divx files on a DVD, then where is the advangage over fitting 3 x SVCD movies (each 2 CDs) on a similar disc?

On the other hand i'm sure you've seen incredible Divx/Xvid quality on a single 700MB cd compared to a 700MB SVCD...1 film on 1 cd in divx looks much better than 1 film on 2 SVCDs, no?

Is there anyone here who captured TV material convert to Divx for a standalone player and can compare it to a normal SVCD quality mpeg2 capture and can explain me a little bit about bitrates and final size?

[theDruid]

I'm not sure if you misunderstood something I said...

I wasn't talking about SVCD's when I said 2 CD's - I was talking about DivX at higher bitrates.

So, for example...

Imagine we have a 1 hour movie (for the sake of argument), and we're going to use 128kbps mp3 audio...

* encoding with DivX at 1500kbps will just about fit this onto a CD.

* encoding with DivX at 3000kbps will just about fit this onto 2 CDs.

The 2 CD set (or just the DivX avi which is 1400mb) will be better quality than the 1 CD version - that just makes sense doesn't it.

That's what I was talking about.

Different codecs were designed to be used within different ranges of bitrates.

MPEG-4 codecs such as DivX were really designed to be used at relatively low bitrates - eg. 1000kbps to fit a movie on one CD.

MPEG-2 was not designed to be used with bitrates as low as this. MPEG-2 is used for SVCD, but also for DVD.

At bitrates round-about 2500kbps, MPEG-2 gives pretty good quality; this is roughly what you'd find on a good SVCD.

DVD uses higher resolution that SVCD, but also uses much higher bitrates in general - e.g. 6000kbps or more.

So, DVD is better quality than SVCD, although they're really just the same codec used at different bitrates (according to the different storage capacity of DVD discs, and CD's).

well if you say that you should be able to fit 6 x 700MB divx files on a DVD, then where is the advangage over fitting 3 x SVCD movies (each 2 CDs) on a similar disc?

You could fit 6 x 700mb DivX movies on your DVD-R. These will only play in MPEG-4 capable players, and each movie will be very highly compressed. There will undoubtedly be some blockiness and artifacts etc.. in the video.

You could fit 3 x 1400mb DivX movies onto your DVD-R. These will be less highly compressed (they have been encoded with a higher bitrate) and therefore will be of better quality. However, these will still only play in MPEG-4 capable players.

DivX will generally outperform MPEG-2 at the same bitrates (when you're talking about low bitrates such as <3000kbps). I'm not so sure this would be true at higher bitrates - that's not really what DivX was designed for.

As for the advantage of SVCD, it's compatibility apart from anything else. Your DVD-R filled with DivX's will play on far fewer standalone players than it would if it were properly authored with MPEG-2 video... and SVCD's themselves will play on far more players than a CD with a DivX video on it.

Does that answer your questions?

cheers,
mcdruid.

[smoki]

yea it cleared up the fog...for now

Quick question: for a PAL TV capture in 4:3 format, what resolution/bitrate should i use so it would look somewhat decent (>2000kbps) AND be compatible with DVD format?

[Gazorgan]

DivX in the 2000-3000 bitrate range looks pretty dam good. I shoot for a 2:1 ratio of MPEG2 versus DivX. 3:1 is pushing the envelope at 720 x 480/576 ( that's the 2 CDR range ), it depends on the movies length ( 80 minute Disney versus 3 hours for Gladiator ). 5.1 Audio can account for a good bit as well.