Block effect around moving objs

[Rash]

Hi there people. I couldn't find any info on this. That's why I'm asking. :)

Do you guys know what causes a "block effect" around moving objects in a movie? It's like tiny blocks around a person when it is moving in relation to the backgound, for example. It's way different from the Macroblocks.

I encoded a movie at 672x288, about 1000Kbps (2 700Mbs CDs), Bframes, GMC and Psycho at normal.

Thank you if you could help. ;)

Reptile

[DJ Bobo]

Don't know what you mean, but generally you should avoid gmc with the actual divx version (still buggy and produces bad artifacts)
Psycho stuff is useless in my experience.

[OvERaCiD23]

encode w/o the GMC and PEs and see if they still exist. there will always be a bit of "ringing" around objects, but on a 2 CD rip it shouldn't be very noticeable. GMC has done nothing but induce problems in my rips, and since PEs don't improve compressibility, why use them?

[Rash]

Thank you so much for you help guys! ;)

People here is saying that I'm too demanding about the visual quality. That it is quite good. Well, maybe they are right.

Anyway, I'll try to encode with no GMC! Thank you so much again! :)

[EDIT] demanding with wrong spelling

[JohnMK]

You might consider lowering your resolution appreciably. What you describe sounds somewhat like compression artifacts that result from using too HIGH of a resolution. And indeed, your resolution is quite high.

Run a compressibility test and pick a resolution to get you to 65% quality. GordianKnot is a great place to do this.

[Rash]

Thanks John.

The first time I saw I thought about that too. But I've seem movies with high resolution like this with great quality. I've also seen some movies I considered to be great quality that I have downloaded and I can also see these artifacts.

Anyway, you're right. I think it was too high (although GKnot showed 50%).

Thanks again pal. ;)

[JohnMK]

50% is way way too low indeed. That's your problem right there. Like I said, damn the resolution, do whatever it takes to get to 65%. Certainly no lower than 60%. If you choose to aim for 60%, I think you'll be so pleased with the trend that you'll have wish you had gone for 65% instead. :D

[Rash]

LOL! Thanks again John. I was aiming a not so low resolution because I thought I could improve visual quality. I exagerated, really. :D

Next time I'll test 60%. ;)

[BluDChyLD]

I agree with john here, but I usually aim a little higher (70%). This usually gives me a nice average quantizer or of around 2.9. Also encoding the credits at a lower quantizer gives you about another 5% too so keep that in mind :)

[Rash]

Err... sorry my ignorance, but what does this average quantizer do?

Another thing: How do you aim 70% without getting a too low resolution (bad for fullscreen view)? Don't you ever do 1CD copy?

Thanks ;)

[DJ Bobo]

The average quantizer doesn't do anything, and isn't supposed to do anything. It is just an information and gives you an idea about the quality of your final encoding: the lower the average quantizer, the higher the quality.

A rip having an average quantizer under 3 is considered to have very good quality.

[Rash]

Thanks. ;) So where do I see this number? Where is it on GKnot, for example?

[manono]

Hi-

One way to find what the final average quant will be is to open the analyze.log right after starting the second pass, and you'll see it near the top. And the percentage figure that GKnot gives you correlates with ave. quant.

If you like nice high resolutions, sometimes you have to go to 2 CDs, or start slapping on the smoothers.

[BluDChyLD]

Originally posted by Rash
Err... sorry my ignorance, but what does this average quantizer do?

As said above the average quatizer is just a guideline to how well DivX has compressed the video.

When encoding a video at default settings the codec will use any quantizer from 2 to 12 depending on how well it can distribute the bits around the picture (2 being the very best, 12 being damn ugly ;)).

How well it can compress the movie depends on numerous factors (resolution used, resize filter, quality of source material etc...). It varies from film to film :)

Another thing: How do you aim 70% without getting a too low resolution (bad for fullscreen view)? Don't you ever do 1CD copy?

I don't use smoothing or noise filters with my rips, and my personal tolerance for resolution is anything of 512 width. Most movies can reach the 70% mark without going below this, if it can't I may use a soft bicubic filter instead of neutral or just use 2 cds...

I also use ogg vorbis for a lower audio bitrate than usual (112) which gives me a slight advantage over traditional mp3 when it comes to overall compression. You should give it a try :)
Hope this helps,
BluDChyLD

[marnum]

I always use denoise filters, sometimes very extreme denoising (yesterday I ripped Road Trip, had only 45 % quality at 512). I only won't use them on movies like Panic Room or SW Episode 2 (which will have a very good compressibility due to fully digital camera equipment). I also use YUY2(PC>TV) to reduce blackblocking.

[BluDChyLD]

I was thinking of using the colouYUY2 filter myself, but judging by screenshots it seems to make the movies rather dark...

[JohnMK]

Originally posted by Rash
Err... sorry my ignorance, but what does this average quantizer do?

Another thing: How do you aim 70% without getting a too low resolution (bad for fullscreen view)? Don't you ever do 1CD copy?

Thanks ;)

Yes, I do 1 CD rips about 80% of the time. Target 60-70% quality. If you go lower than that, mpeg-4 starts to produce these ugly compression artifacts that look much uglier than than the artifacts you get from using lower resolutions.

[Rash]

Oh, thank you all for your help! ;)

Bludchyld, I use Ogg too. I use always 96Kbps on it, because I think at that bitrate it is really close to MP3 128Kbps. I like it, but sometimes it is easier to make the AVI format. :)

I'm encoding Impostor tomorrow. Then I'll use my new knowledge on this. ;)

Thanks