Quality at low bitrate, I'm convinced but how ???

[apfraats]

Ok I have to admit. Looking at a movie with BELOW 1700 kbps is possible, despite my own opnion that I considered below 3500 mission impossible.....

So I did a bet with someone and didn't expect awesome quality, but a watchable movie. He told me he could do it with a 3,45 Hours lasting footage with DTS AND 5.1 DD tracks...

I just laughed and did the bet. Now I'm sorry about that because it costed me 100 empty DVD's..........

But I was suprised. He didn't want to say how he did it, so I asked him to leave the DVD for evaluating for a few days at my place.

I never believed below 3500 Kbps average (as a rule of thumb) 'fair' results could be reached.

But sure, he showed me a DVD with under 1700 Kbps average VIDEO....

It's watchable (sharpness=0 which still gives a fair picture), not superb quality. If you stop and use picture step forwards backwards you can even see a few blockings now and then.

But if you play it normally it just looks 'great', of course a big suprise for me.

I extracted the matrix used. It was the standard Mpgeg-2 matrix.

He won't tell me the trick.....

And I lost 100 DVD's.... :mad:

I use CCE and even tried HC but can't possibly come any near the 'original' dvd.

Even reencoing it at 100% messes up everything..........

There were fairly high Q-values and peaks with bitrate viewer.

You won't get these with encoders I tried.

Someone any idea how it's possible to get 3,45 hour video and DTS + 5.1 DD on a 4.36 GB DVD ??????

[Matthew]

Did he destroy the clarity by using half-D1 and/or blurring filters?

[apfraats]

As far as I see the picture, nope.......

Have to try half D1 however, don't even know what it does, but it should be 1/2 resolution or something ?

[Matthew]

Half-D1 is 352 x 576/480

I find it hard to believe he didn't use a form of blurring, like with those 10 line KCrap scripts. Search for kdvd, he may have used that method.

[manono]

...like with those 10 line KCrap scripts.

Hehe, that's funny, Matthew.

Yeah, after I read apfraats' first post I was thinking to myself filtering. Then you chimed in with 1/2 D1, and that's an even better idea. apfraats, I'm sure there are many ways to get the resolution, but one way is to open the DVD in DVD Decrypter set for IFO Mode. Then hit the Stream Processing Tab and it will tell you the video resolution. If it's really 352x576, then 1/2 res is about equal to 1/2 bitrate for the same "quality", and there's his "secret" right there. That and maybe some additional filtering. Must look fairly blurry though.

[Mug Funky]

temporal median filtering is a powerful way to make a movie more compressible at very little cost to perceptual quality.

a clean source helps too, and horizontal blur is very seldom noticable on a TV.

also shrinking the image to 90% it's size and leaving black in the overscan areas saves a fair bit of space.

then you can encode extremely low, and segment-re-encode all the problem areas with a higher bitrate and even heavier filtering just on those scenes.

or you could do all the above...

but who the hell wants DTS on a DVD-5? i mean really... half-rate DTS is only good for optical tracks (which are usually only stereo or mono or matrixed surround, so 5.1 is useless), and full-rate DTS takes up way too much space for something that's only distinguishible from ac3 on worst-case samples (which almost never occur in movies).

[edit] though it was stupid for the guy to use MPEG standard IMHO. for such low bitrates you'll want to trade off highs (blurring) for lows (blocking), especially on a pre-blurred source.

[wmansir]

Half-D1 was my first though too. I just did the SW:III bonus disc which had about 4 hours of material on it with Half-D1.

Re: manono's method. It is possible the .IFOs were left at Full-D1, which would still work in most players. I'm assuming DVD Decrypter uses the .IFO info, so it may not be accurate. A quick way to double check is to just drag-n-drop one of the .VOBs into DGIndex. It displays the true resolution regardless of the .IFO.

EDIT: Also, Half-D1 will produce noticable aliasing on sharp pictures due to the resizing. I haven't purposefully used a blur filter to "fix" the problem, but I have noticed softer pictures do better with Half-D1 and I imagine a blur filter could be used to mask the aliasing effect.

[SAPSTAR]

Just to add my small contribution...it's also possible to do Half-D1/Half-V1 => 352*288 which is perfectly compatible with the DVD specs and you need a quarter of the bitrate => 1000 kbps ~ 4000 full res. And there are less artifacts than the Half-D1 res...at least for my eyes.

[blutach]

I did Hitch R4's extras (what ones I wanted) in 1/2D1 to ensure the main movie was uncompressed. No filters just half D1 - a little bit of ringing here and there but overall fantastic. Got me thinking to play around with it on real long DVDs.

Regards

[dragongodz]

Half-D1/Half-V1 => 352*288
this is generally called quarter D1.

Got me thinking to play around with it on real long DVDs.
its very good for combining several kids dvds on to 1 aswell. :D

[Msc_Alex]

Someone any idea how it's possible to get 3,45 hour video and DTS + 5.1 DD on a 4.36 GB DVD ??????

Well the DTS track has to be 768 kb/s and the AC3 for 5.1 must be 256 kb/s (normally 448 or 384 is used for 5.1) Then you use a CCE 4 Pass VBR with average 1700 max 8776 and 1/2 D1 the cvd format :p .

Personally i would have made the 5.1 ac3 -> 128 kb/s 2.1 AC3 Would gain a extra 100 kb/s for the video :)

[jptheripper]

what are the filesizes of the audio tracks?

[rendez2k]

Are there any negatives to doing a 'difficult' whole disc in half-D1?

[SAPSTAR]

Are there any negatives to doing a 'difficult' whole disc in half-D1?
Sharpness....but if your screen is small it doesn't change much.