What are microBlocks?

[joshreid2002uk]

I have blocks at the begin of my films which block up the film with movement it goes sometimes with some avi films but when i convert mpeg2 to mpeg-1 VCd it does it more also it affects the sound sometimes crackles with the blcoks when it come up.
Hi whoever can help me please!
I have tried in the past downloading many films and they have been a success playing them on my P3 866Mhz computer i use Tmpeg to convert many films from reading this site which works but i have two problems playing it on my PAL dvd palyer sony dvp300 priced rougly at £149 at the minute if you know. the problem is that i get block of the pciture blurr up and make some of the audio crackly but goes away after i have got further on in the films i have done mpeg2 and avis to VCDs to 25fps the other prob is that the motion of oceans eleven is slow with the movemnet is it doesnt to do with the bitrate that the film is set at. Please help anyone!!

[MOVIEGEEK]

"Microblocks" are artifacts caused by:
1)capturing under 2000kbps
2)burning at <2x
3)non-compatible drivers(update the drivers)
Use a filter when encoding to mpeg.
Good luck

[mol3000]

i am having the same problem with blocks all thru a movie when i am converting..... on both TMPGenc and panasonic..... what kind of filter should i use for each of them and where do i find them ?????

[Douglesh]

2)burning at <2x

Never EVER heard that one before. Care to explain please.?

[mol3000]

can anyone else help????????

[dphirschler]

I don't know about "microblocks" but I have heard about macroblocks. It refers to digital artifacts apparent in your video. The two different kinds of digital artifacts that I've heard mentioned most frequently are marcoblocks and mosquitos.

Macroblocks are large blocks (about 16x16 pixels) that appear in your video. Sometimes macroblocks are described as brightly colored blocks that have no place in the video. Other times it is used to describe large blocks of data that seem to be from the video frame (or nearby frames), but are out of place.

At Scientific Atlanta, we also used the term "Macroblocking" to describe the way a digital channel comes into view. Over a period of 2 seconds or so, an image will "paint" itself on the screen randomly a block at a time when you tune to a digital channel.

"Mosquitos" is a term used to describe pixel data near edges which seem to move around like mosquitos. This is caused by the jpeg-like compression of mpeg. Sometimes an overcompressed video stream will exhibit this artifact so badly that it is distracting.

Hope that helps..


Darryl

[mol3000]

" Macroblocks are large blocks (about 16x16 pixels) that appear in your video. Sometimes macroblocks are described as brightly colored blocks that have no place in the video. "

thats def one of the things happening... in one movie (jurasic park 3) it comes up when actions scences comes up and this other movies it just comes in and out even when there is no action..... so what filters or settings i can use to get rid of it ?????

[You_Are_Alive]

I am getting the exact same macroblocks right, now! I have tried all the templates, Tibro, Pinnoy, Sefy, it doesn't matter. I modified them too, clicked noised reduction and soften blocks. IF I increase the bitrate over 1150, looks better but when played on my dvd player, it give the wrong time eg. clip is 12 min but player displays 28 min. Picture quality is there now but all the video action moves very jerky along with the audio. Guess because I'm out of VCD spec.

So am I right in thinking that instead of feeding tmpgeng with my mp2 and wav files, I should retry giving it a muxed uncompressed avi file? Then use the VCD spec? Any ideas? Has anyone successfully gotten rid of the macroblocks with VCD specs, it seems impossible at such a low bitrate.

FYI the mp2 file (mpeg2 elementary stream) was captured at 8000 kb/s... and using tmpgeng 2.53.

[Sefy]

I'm starting to believe it's not your movie or your encoding, but the way your DVD Player plays the movie, i've seen the same movie being played on some DVD Players, and some play it badly, while others make it looks so sharp it's unbelievable.

To make better conclusions, check the same movie on a diffrent DVD Player, not to mention your DVD is a Sony, and i consider those as the worst quality, especialy when it comes to VCD's.

Secondly, your source according to what you said, is an AVI file, so no matter how you look at it, it will NEVER be a smooth quality, cause your source is already highly compressed and doesn't provide enough input for any encoder to work with.

[You_Are_Alive]

So has anybody else been able to almost eliminate the macroblock effect using a compliant VCD template? Or why is it that when I encode with a higher bit rate eg. 2500 for mpeg1 or even 2000, my play duration is so off. Check my previous post.

Okay so for those who are a bit lazy, here it is:

I am getting the exact same macroblocks right, now! I have tried all the templates, Tibro, Pinnoy, Sefy, it doesn't matter. I modified them too, clicked noised reduction and soften blocks. IF I increase the bitrate over 1150, looks better but when played on my dvd player, it give the wrong time eg. clip is 12 min but player displays 28 min. Picture quality is there now but all the video action moves very jerky along with the audio. Guess because I'm out of VCD spec.

[Sefy]

I see you haven't paid attention to what i said, did you try playing the VCD on a diffrent DVD Player ?? you already said when you increase bitrate your DVD shows incorrect time.

[You_Are_Alive]

First, the question still stands: So has anybody else been able to almost eliminate the macroblock effect using a compliant VCD template?

To Sefy,

I think you may have mixed up the posts, I never said I have a sony dvd player, joshreid2002uk did. From the way I read your previous post, it seemed that it was not addressed to me and seemed more that it was aimed at the originator of this post, joshreid2002uk.

So now that I think your talking to me, I don't see the relevance of trying my VCDs in other players rather then the Sony ones cause I need to distribute this disc to about 10 people and 8 of them have Sonys. So I guess you can see that in my case, it must be a Sony. It shows these blocks on my Sony unit, so I know its gonna show up on theres too.

Any good recommendations welcomed ! And thanks for anyone who attempted to help, Sefy and hopefully others.

Side note: Have seen alot of these blocky and jerky posts spring up like crazy after this original post on the forum. Also when playing the VCD with Quicktime, the correct time, 12 min is shown. PowerDVD won't even accept the file.



[/b]

[vhelp]

you,

How-bout this, post the title/name of the movie you are
having trouble with. That would be really helpful.

* movie name
* source, ie, dvd/vhs/satalite/dv/dig-8, etc.

Also, WHERE in the scene do you see these blocks.
Also, have you tried using SVCD or xSVCD or better yet,
CVD to see if you get any better results or variations in quality???
If you tell us, maybe we might have this movie and see for ourselves
what's going on and/or be able to help ya

* R U trying to make vcd/svcd etc or R U making for playing
on your PC monitor??

WinDVD 3.0 is the best player for playing and judging quality
cause it doesn't show any artifacts as PowerDVD does.
Also windvd plays VCD's better than powerdvd, w/ less blocks or
artifacts.
You may want to try D/L'ing it, even the trial version.
Yes, I have and use the trial version, but it's a pain in the AZZ
cause my time limit has expired and it drives me crazy to change
my system date every day in order to use it. It expired in march.
So, now I have to jimmy my clock to view my 10 second clips, darn
This is the only drawback to WinDVD, otherwise, its the best!!

-vhelp

[Sefy]

You_Are_Alive, my apologies, I was refering to the original poster.

As for your question, I still suggest you try playing back on another DVD, just to see if the problem is the VCD or the DVD.

If the problem is indeed the VCD, then you can concentrate more on optimizing, if it's not, then you know atleast you haven't got much to do about it!

[dphirschler]

Sometimes macroblocks are just gonna be there. If the player has a problem with the disc, it may have blocking. Or if the disc has problems it may have it. Also, if the blocks are in the video stream then no amount of filtering (that I am aware of) will remove them. Sometimes when you download a video, some bits here and there can get corrupted causing macroblocks.

If there is a filter out there that allows someone to take an offending frame into a paint package and repair it, I'd like to know about it. There is one that allows you to take an offending frame and either black it out or have another frame copied over it. It's called Tweak.


Darryl

[MITSUI_1]

There are really only two causes of a "macroblock".

The first is a bad disc data sector and you can deal with that fairly easy. Here's what you need to understand. VCDs and SVCDs are stored on CDs in such a way that they use the area of each block normally allocated for error correction information to store regular video data. That's why you can fit 800mb of VCD on a "700mb" disc. But what this means is if you get a glitch, there's no error correct. Now, what does a glitch do in the MPEG stream? Well, its a problem. MPEG uses discreet cosign transform math functions to store data from "blocks" that are 16x16 pixels in size. If the data for a particular block gets corrupted or read into the decoder incorrectly, that block will not look right. Since that entire block will be corrupted, it will "stand out" from the others on your screen. That's why crappy discs sometimes lead to macroblocks.

The other cause for macroblocks is bitrate starvation. Picture it this way. As the amount of bitrate allocated to each second of video decreases, you'll approach the point where the amount of data available to certain macroblocks (those in high motion areas, in particular) is simply not enough to encode all of the detail in that block of space. All encoders work by throwing away information they cannot "afford." They cannot "afford" the information if encoding it would increase bitrate beyond the maximum or CBR number you've told the encoder to use. Suppose the encoder is doing a scene with complex high speed movement (like fire). If you don't have enough bits, all of the detail won't be encoded. At an extreme, the encoder will be able to merely get the "color" for the entire 16 by 16 block right. All "spec" VCDs will have macroblocks at high motion scenes. There is no way to completely avoid it. There ARE some tricks you can use to "conserve" bitrate, such as encoding a black strip for the top and bottom rows of macroblocks (which lets those macroblocks take almost no bitrate, and allows the encoder to move the extra bits to other macroblocks on the screen that might be starving). Additionally, you can go with billinear resize using AVIsynth or VirtualDub, as opposed to bicubic resize. The reason is that bilinnear is not as sharp, and a high level of sharpness actually requires more bitrate to encode properly. Too much sharpness will result in macroblocks.


Lets see, other ways to conserve bitrate: If you're working with SVCD that is "film" based, you can do an inverse telecine and encode at 23.96 fps and treate the stream with pulldown.exe to save bitrate that way. (this actually saves 20% of your bitrate). In addition, for SVCD you can use 1/2 D1 resolution (352x480) instead of regular SVCD bitrate (480x480). This will save you yet ANOTHER 25% or so worth of bitrate. What you end up doing is having more bits available per macroblock, which is the key to avoiding blocking artifacts.

[You_Are_Alive]

MITSUI_1 thanks for re-affirming what I thought was the limitation of the VCD spec but your the first to actually state it. I think you read my mind, my video intro is filled with fast motion scenes, and the first is a FIRE.

As such, only solution for me is to go to DVD or just have it play on computer only and forget about it running on a settop player. 8)