Does x264 inherently de-noise/de-dither DVD video and reveal blocks?

[*.mp4 guy]

Originally Posted by elguaxo

You mean: --direct auto -> --direct none
or leave out this: --weightb

I meant the first one.

Originally Posted by Manao

Won't work, you'll only complicates the codec's job. Debanding / adding noise during the playback is almost the only way to go ( at the moment - when adaptive quantization will work effectively in x264, it might solves the issue in a more satisfactory way )

The noise will help if deblocking is disabled, and you use a cqm, it would be rather useless if you had the deblocker enabled, and used the standard matrix. I wouldn't recommend adding noise normally, but the problem here is that that gradient is to fine to be adequately preserved in yv12 and x264 is killing the dithering, adding more noise will provide stronger dithering that x264 is more likely to keep.

[j7n]

I tried adding grain. The improvement was very subtle. Noise didn't spread across the whole color band, but only made its edges "shimmer" quickly and didn't look like real dither at all. The source is very clean and perhaps that is its "problem".

ATM I'll stick to debanding, and of course keep the source MPEG-2.

Does AVC include provision for generating noise on the decoder side only when needed without actually trying to encode the exact dither? Adding more noise to the whole picture is not an option.

[Manao]

Does AVC include provision for generating noise on the decoder side

Yes

only when needed

Not quite. It allows to configure the noise parameters for each pictures. And - iirc - the noise parameters can vary with the luma of the pixel ( i.e, more noise on black pixels than white ones ). That's not quite exactly what you'd like, but it's alredy a start. The drawback, of course, is that the noise generated is inherently random, and not temporally stable, while what you actually want is a proper dithering.

Adding more noise to the whole picture is not an option

Why ? Even studios add noise to CGI movies. It looks (almost) always better.

[j7n]

the noise generated is inherently random, and not temporally stable

Yes, that's the right description of why AddGrain() didn't look suitable.

I meant more than Addgrain(4, 0.2, 0.3).

[foxyshadis]

Maybe you could try something like:
mt_average(AddGrainC(2),AddGrainC(2,seed=10))

Add in hcorr and vcorr if you really want them. Seed makes it constant across a video. This way the noise is somewhat stable and somewhat not. Or use the average plugin for finer weighting. (A plain screen pattern, ie no temporal randomness, just looks weird though.)

There's a lot of very interesting things you can do with noise - search for noise factory for one of them. The noise should have different weightings depending on if it's a light or dark area, and detailed or smooth, and AVC grain deals with that.

[bananacreamandpeca]

Originally Posted by *.mp4 guy

If you wan't to try a cqm, this one should work well, though you should change Bframe predict mode to none to stop X264 from behaving badly..

Are you talking about the "weighted B-Prediction" option?

Seems like these blocks are a issue for lots of others as well.
(thought I was the only one)
And thank you all for trying all the other options I jotted down to try, before I did (and prob made me yell and
curse at everyone because it didn't work)
Saves a hell lot of time

[bananacreamandpeca]

Originally Posted by Mug Funky

ex-gov CRTs FTW!

if you ebay for it, you can pick up 19" or even 21" CRTs for as little as 20 bux.

i got mine at a swap meet for a fair bit more than that, but still pretty cheap for a trinitron.

only problem is space.

That last line was funny.

I also use a trinitron monitor. Don't know about the quality.
But seems alright to me. (CTX PR-711FL prob a cheaper trinitron model)

[Morte66]

Originally Posted by bananacreamandpeca

Are you talking about the "weighted B-Prediction" option?

He means using --direct-none to change Bframe predict mode to none with that matrix. B-frame prediction can act funny with strong CQMs. This costs a lot of bitrate, only use it if it looks obviously better. [Most people use --direct-auto unless they have a reason not to.]

This is an old thread, there's an updated version of that matrix which I linked in the other thread you just started.

Seems like these blocks are a issue for lots of others as well. (thought I was the only one)

It's a quiet split in the Doom9 community. Some of us are really bothered about blocking on DVD encodes, others can't see what the fuss is about. I don't know if it's about perception or it's just that some people have display set ups that reveal blocking -- LCDs, dark rooms, high contrast, close viewing etc.

[nm]

Originally Posted by Morte66

It's a quiet split in the Doom9 community. Some of us are really bothered about blocking on DVD encodes, others can't see what the fuss is about. I don't know if it's about perception or it's just that some people have display set ups that reveal blocking -- LCDs, dark rooms, high contrast, close viewing etc.

It's probably a bit about all those things. For example, I have a couple of CRTs, a laptop LCD and an LCD projector. Blocking is not a big problem with any of these particular displays. I can see it if I look for it, but it doesn't bother normal viewing at all. However, a friend of mine has an older LCD panel which makes x264-encoded video look horrible. That's because the panel only has 18-bit colors (I think), and even worse, it displays dark colors with peculiar shades that can be told apart very easily. This makes blocking really stand out. The result looked like something one would expect to see at YouTube rather than in a DVD rip.

[R3Z]

Originally Posted by Morte66

It's a quiet split in the Doom9 community. Some of us are really bothered about blocking on DVD encodes, others can't see what the fuss is about. I don't know if it's about perception or it's just that some people have display set ups that reveal blocking -- LCDs, dark rooms, high contrast, close viewing etc.

I agree wholeheartedly here. Frankly, its quite frustrating that one needs to resort to using custom matrices (especially those that actually smooth the whole picture) when most of us are trying to keep all the precious details we can.

I find that adding grain during playback totally eliminates the blocking and i would really like to see some sort of option in the encoder to add grain during playback. I know this would mean that the decoder must be able to handle that feature?? and not sure how one would go about it.

I am just very lucky that i find grain and noise as a great thing. Some people hate it !

[Mug Funky]

h.264 supports "film grain simulation" which does what you ask.

x264 doesn't support it, and most (all?) decoders don't. but it's likely to be supported in the future, when it becomes less fashionable to overfilter encodes.

[check]

troll? It must be.
In any case, the nitpicker within me wants to point out that the feature is actually named "film grain modelling" (at least, that's what I've seen it referred to as).

[bananacreamandpeca]

Am trying a few things of my own to reduce those nasty looking things in the output.

I was wondering. If turning deblocking to off. Would that make things worse when trying to reduce those blocks?
Some say I should turn deblocking up
Some say to lower the value to a negative value

[Morte66]

Originally Posted by R3Z

I am just very lucky that i find grain and noise as a great thing. Some people hate it !

You certainly are lucky, I don't like noise much.

[Morte66]

Originally Posted by bananacreamandpeca

Am trying a few things of my own to reduce those nasty looking things in the output.

I was wondering. If turning deblocking to off. Would that make things worse when trying to reduce those blocks?
Some say I should turn deblocking up

Easy to try.

Some say to lower the value to a negative value

For what it's worth, I think of the Deblocking settings in x264 as a sharpness control. They have a strong effect on sharpness, -2-2 looks like Xvid 1.2 and +0+0 looks like DivX3 (IMVHO, YMMV, taste is personal, etc). Whilst they do also effect blocking overall, it's minor compared to the blocks on the DVD you're encoding from and it has a minor effect on smooth/dark areas compared to a CQM.

If I'm encoding from a clean uncompressed source without any blocking (as I have done once or twice to experiment), x264 deblocking matters a lot more.

[Single]

I think all people who tries to do a details looks at coding results mast do a monitor calibration at first of all. Most of LCD monitors has a very very bad linearity compared to a cheap CRT. Calibration is a gamma at first than britness and contrast.

[bananacreamandpeca]

Can 'enabling CABAC' cause these blocks in x264?
No one ever mentions it. It says it can decrease bitrate with no Q. loss.
So how does it do that?

[akupenguin]

how it does that

[Sharktooth]

Originally Posted by bananacreamandpeca

Can 'enabling CABAC' cause these blocks in x264?
No one ever mentions it. It says it can decrease bitrate with no Q. loss.
So how does it do that?

Does zipping a file decrease its size without loosing data? ... (answer: yes)
CABAC does the same with the bitstream (well, cabac is a bit more complex than the zip/deflate algo though...) so it doesnt affect image quality at all.

[shon3i]

Yes, but zip is lossless process, and nobody can confirm that is CABAC 100% lossless.