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Cunhambebe
11-02-2004, 12:13 PM
Hi there. Some people around here may already know I am a newbie. So, this time my question (s) is (are) how to render the right way with Lightwave. After setting a scene, I set may camera options at NTSC 720x480 and on the render guide, I select save animation as AVI uncompressed and RGB files as Targa 32. I hope this is the right way to render files with Lightwave (I know you can choose Quicktime, etc...). The AVIs seem so perfect as well as the Targa sequence files. Unfortunately, as soon as I try to render the outcome as MPEG2 with Vegas' Main Concept Built-in MPEG encoder as well as with TMPGEC or even Canopus ProCoder, things start to go out of control. I mean, I get a lot of banding on video. Let's see this:

1.If I render the AVi file as MPEG2, the MPEG 2 is darker but I don't seem to get those bandings.

2.If I render the Targa sequence, I get those bandings.
I tried every configuration possible with those 3 encoders (Canopus, TMPGENC and Main Concept). I also tried modifying the camera options for 720x486, despite the fact the result was the same = banding.

I know this may be a problem with those MPEG encoders. Canopus showed to be the worst at even the highest bitrate; TMPGENC was better, and Main Concept, for my surprise was the best at 9.800 kbps. Please take a look at hose pics.

What I'd like to know....
1.Am I doing something wrong while choosing those settings with camera and render with Lightwave?
2.Are those bandings normal because MPEG encoders cannot follow Lightwave excelent render capabilities?
3.Why rendering an AVi file as MPEG will result in a darker video and why rendering a Targa sequence will result in the inverse, a clearer video file?

Now, this is for my curiosity: I know all Babylon 5 was produced with the help of Lightwave. I was just wondering what options they choose to set the camera and render.....Maybe they chose to render at a much higher resolution than 720x480/486.....Help please.....

Thanks in advance. Help will be greatly appreciated.

PICS - from top to bottom: 1. Canopus; 2. TMPGENC; 3. Main Concept.

Dodgy
11-02-2004, 04:15 PM
For a start they all render to still frames first, then usually laid them out to tape using hardware.

Rather than rendering a movie straight off, render still images first, then load them in as an image seqence and put that in as a background image. Then you can use LW to render out the animation, and it's a lot easier to tweak the animation settings.

Cunhambebe
11-02-2004, 07:02 PM
Thanks...but these pics, they were all sequence files rendered as MPEG2 (DVD compatible). How about those bandings? By any chance, can the problem be something related to "color space conversion"?
Thanks again

Cunhambebe
11-03-2004, 06:37 PM
Anybody? Anyone? Is there a single living soul around here????

theo
11-03-2004, 09:22 PM
It's called Casperitis Cunham- :D

Silkrooster
11-03-2004, 09:57 PM
At the moment I can only think of two things it could be.
1) The mpeg encoder is converting your images to 8-bit files. Causing a reduction in colors, therefore banding.
2) The mpeg files are being compress too much. Causing vital data to be thrown out, resulting in banding.
Perhaps the encoder is having trouble with the tga files, try using 24 bit files with no compression, or try another format all together, such as psd or tif.
Silk

Red_Oddity
11-04-2004, 03:11 AM
The reason you're getting color banding is because your compressing in MPEG-2, and MPEG-2 uses a 4:2:0 color spacing...

If you want to know what i'm talking about here i suggest you take a peak here (http://www.adamwilt.com/DV-FAQ-tech.html#colorSampling) and here (http://codecs.onerivermedia.com/)

Dan Measel
11-04-2004, 10:26 AM
I am a new LW8 user as well and I'm trying to figure out what program to use to convert a sequence of targa files into an avi. Can anyone recommend programs they use to do this? Sounds like the three programs Cunhambebe is using are not ideal. Thanks.

Silkrooster
11-04-2004, 02:42 PM
Most video editors will import still images that you can use to create an avi from. Pinnacle Studio, Adobe Premeir are two that I know of and I am sure several others can two.
Silk

mrunion
11-04-2004, 02:51 PM
You can just use LW to bring back in the sequenced frames. Just load a backdrop that is an image sequence, use the images you rendered, select how you want the "movie" created -- avi, qt, etc., then render it. It will zip through the images and create a movie from them.

Red_Oddity
11-05-2004, 05:13 AM
I can suggest to do 2 things that will assure you get compression, but without quality loss...

Render in QT in Animation @ 100% (this uses a Run Length Compression, which is a lossless copression)

Render in AVI with Pegasus Imaging's PICVideo codec (http://www.pegasusimaging.com/picvideolossless.htm) (which is a JPEG lossless codec)


Or render using no compression, and when your done with your project backup the rendered images in a RAR file on the best compression setting.




This is what i usually do, and so far, we've always had superiour output to this way , whether it was on MPEG-2, DV, Betacam SP or Digital Betacam.

Just remember, crap in, crap out...so make sure your sources before compression are always compression free/ lossless

11-05-2004, 05:34 AM
1) Repeating what several people have said, but it REALLY is the way to go:
ALWAYS RENDER UNCOMPRESSED IMAGE SEQUENCE.
then you can quickly try lots of comression settings on your image sequence without having to re-render, with the added attraction that if the rendering breaks down you only loose a few frames.
2) Never 're-compress' if you can possibly help it, always start with a clean uncompressed sequence. Remember that lossless compression is a theoretical concept, not a usefull possibility in most circumstances.
3) Compression - even (perhaps especially) to DVD is an arcane art. It is NOT one setting fits all, it never works well as 'push the button & go'. I suspect that comercially converting movies to DVD is still done by skilled operators viewing, analysing and continually changing the compression settings between shots.
4) For avi I get the best results from DIVX codec - search, download & install it on your computer, LW will pick it up and be able to 're-render' your sequences (loaded as background images) to it. Multipass gets the best results if you stick with it - remember to save the settings when ever you get a good result for a particular type of scene!

Lightwolf
11-05-2004, 06:01 AM
Perhaps the encoder is having trouble with the tga files, try using 24 bit files with no compression, or try another format all together, such as psd or tif.
Erm, Targa files only use lossless compression, so that can't be the reason.
I'd assume this is a colour conversion problem as well. The images look very smooth, try adding some dithering to the LW render, the MPEG2 encoders might like that better.

Cheers,
Mike

11-05-2004, 06:50 AM
OK, I'll admit that the lossless compression in a tga file or maximum quality jpg produces an image indistinguishable from the original - but that is not the same as 'identical'. Short of using a completely uncompressed avi or other form of uncompressed movie file, any subsequent 're-encoding' produces a movie file containing less information than it would have if you'd started with uncompressed images.
(Hm, does that make sense?)

Lightwolf
11-05-2004, 06:57 AM
OK, I'll admit that the lossless compression in a tga file or maximum quality jpg produces an image indistinguishable from the original - but that is not the same as 'identical'.
...
(Hm, does that make sense?)
Looks like we're hijacking the thread here :)
Don't mix up compression and compression here. The difference is "lossless".
JPEG compression is always lossy, TGA compression is never lossy.
If you decompress a TGA image, and compare it to the original image bit by bit it will be identical.
With JPEG it won't be (well, there is a subset used by some video editing boards, but I'm leaving that out because it is only a partial JPEG compression, which ends up being close to LZW).

Lossless compression schemes are for example LZW (used by tif and openEXR, as well as ZIP and other compression tools), RLE (used by TIF, TGA and BMP).
Lossy compression includes JPG, MPG(1, 2, 4), Cinepak ... whatever.

TIF is a nice example of a fileformat that supports lossless (RLE, LZW) compression, as well as lossy compression (JPG).

No offense please, I just wanted to clear this up :)

Cheers,
Mike

Cunhambebe
11-05-2004, 09:29 AM
Finally, tehre ARE some living souls around here! lol
Thanks to all who took time to respond ;)

Silkrooster:
1) The mpeg encoder is converting your images to 8-bit files. Causing a reduction in colors, therefore banding.
-No sir, Targa 32 are already 8 bit files

2) The mpeg files are being compress too much. Causing vital data to be thrown out, resulting in banding.
-No sir, there isn't that much compression at all. Those pics show all compressors at full bitrate possible for MPEG2 files......

...try using 24 bit files with no compression, or try another format all together, such as psd or tif.
-24 bit files are the same...without alpha.....

Red_Oddity:
The reason you're getting color banding is because your compressing in MPEG-2, and MPEG-2 uses a 4:2:0 color spacing...
- Can u please tell me how to fix that????????Thanks in advance.

Dan Measel:
I am a new LW8 user..... what program to use to convert a sequence of targa files into an avi...

-Adobe Premiere Pro, After Effects, both can do that....Want a more simple one and that works much better? Choose Sony Pictures Digital Vegas Video 5.0 (free trial version for download at Sony). The only drawback with Vegas is that it CANNOT do extrusion and After Effects can.


Red_Oddity:
I can suggest to do 2 things that will assure you get compression, but without quality loss...
Render in QT in Animation @ 100% (this uses a Run Length Compression, which is a lossless copression)
-Haven't tried that yet.

Render in AVI with Pegasus Imaging's PICVideo codec (which is a JPEG lossless codec)
-Sorry here, but rendering as AVI and then re-render again later as MPEG2 makes a horrible result. MPEG2 fiels rendered this way are darker, horrible - still don't know why.

...Or render using no compression, and when your done with your project backup the rendered images in a RAR file on the best compression setting.
Just remember, crap in, crap out...so make sure your sources before compression are always compression free/ lossless
-Sorry again, but as you choose to render as RGB, Targa 32, where is the screen that let's you choose between compressin and no compression? That screen only pops-up as you choose to render as AVI or Quicktime, isn't IT???? SO I JUST WANNA MAKE YOU UNDERTAND THAT TARGA 32 HAS NO COMPRESSION AT ALL.

[email protected]:
ALWAYS RENDER UNCOMPRESSED IMAGE SEQUENCE.
-I DO, I DO!

then you can quickly try lots of comression settings on your image sequence without having to re-render, with the added attraction that if the rendering breaks down you only loose a few frames.
-I know that, thanks anyway.....

2) Never 're-compress' if you can possibly help it, always start with a clean uncompressed sequence. Remember that lossless compression is a theoretical concept, not a usefull possibility in most circumstances.
-Sorry, but MPEG2 files are compressed; it's a format for distribution and I always render sequences as Targa 32.

3) Compression - even (perhaps especially) to DVD is an arcane art. It is NOT one setting fits all, it never works well as 'push the button & go'. I suspect that comercially converting movies to DVD is still done by skilled operators viewing, analysing and continually changing the compression settings between shots.
-That's for sure. Did you see my pics?...Even Canopus ProCoder 2.0 couldn't do a good job. And that's why I state this once again: MPEG2 is not a format to store your precious files......

4) For avi I get the best results from DIVX codec - search, download & install it on your computer, LW will pick it up and be able to 're-render' your sequences (loaded as background images) to it. Multipass gets the best results if you stick with it - remember to save the settings when ever you get a good result for a particular type of scene!
-I'm sorry here, but it seems that Huffyuv is the best codec for AVI, the only one that compresses with no loss of quality, but thanks for the input (go to www.videohlep.com and find out more about that!) Please read my remark above on AVIs = rendering this format as MPEG2 is not a good option; MPEGs are much darker this way.

Lightwolf:
Erm, Targa files only use lossless compression...
-That's IT!!!!
...so that can't be the reason.
I'd assume this is a colour conversion problem as well. The images look very smooth, try adding some dithering to the LW render, the MPEG2 encoders might like that better.
-So, do you have a guide on how to fix this?

Please, I do invite all of you to go to

http://www.videohelp.com/forum/viewtopic.php?t=243319

...and....

http://mediasoftware.sonypictures.com/forums/ShowMessage.asp?MessageID=328119&Page=1

Let's see if we all can find an answer...
Thanks again.

PS: So, where do we wind up? How can I fix those bandings? :D

Lightwolf
11-05-2004, 09:36 AM
Lightwolf:
Erm, Targa files only use lossless compression...
-That's IT!!!!
...so that can't be the reason.
I'd assume this is a colour conversion problem as well. The images look very smooth, try adding some dithering to the LW render, the MPEG2 encoders might like that better.
-So, do you have a guide on how to fix this?

Well, if you care to re-render, open the Effects->Processing, Increase the Dither Intensity and may be turn on animated dither.

If you have a comp tool, add some grain.
Mind you, this will not remove the problem leading to the banding, but it will hide the banding in a bit of noise.

May be the colour conversion from RGB 8 bit to YUV 8 bit (plus the reduced chroma sampling, as was mentioned before) plays a role here as well. This tends to vary in quality from encoder to encoder (I use TMPGEnc and so far never had any banding).

Cheers,
Mike

11-05-2004, 11:30 AM
Hate to say it but the statement of the oroginal problem excludes a solution.

IMHO it appers that mpg2 is not a suitable format for storing or distributing your stuff. It's basic definition includes a limited colour space or palette which means that it cannot store enough different colours to stop your animation looking banded. Uncompressed avi (or VT) for short term storage - but most people cannot find enogh HD space to use it for archive purposes and end up backing to some form of video tape, proper digital video is out of reach of most budgets, I compromise on sony DVCAM - which does still have a limitation in colour space, but is a vast improvement on VHS, and certainly on mpg2.
For 'transmission' you just have to go for the best compromise of file size for the job in hand - fit the compression rate to the capacity of the distribution medium - that's why I use DivX.

cgbloke2004
11-05-2004, 12:18 PM
lots of people here have said the same thing, and i'll only echo what theyve said, so i'll keep it short.

your problem with banding is that youre using mpeg-2.
its an efficient, if very lossy compression format. its like if you were saving all your files as 75% quality jpeg's and wondering why the quality doesnt look good.

Look at any commercial DVD with a fair amount of CG in it -
Luc Besson's 'The Fifth Element' might be a fair examplehere - usually regarded as a pretty good standard of picture quality vs compression - look at the exhausts from the spaceships - lots of banding.

Its not because the sequence was rendered 'badly' in the first place - it is because of what mpeg-2 compression did to it.

DV has a similar problem in that it is also storing data in a lossy-ish format - so storing on DV is not a solution either.

solution?
keep rendering to uncompressed file formats as you have done, and then keep it that way - buy up lots of hard drives to store them on..

when you do need to distribute - theres a couple of things to consider:
who you are sending it to, what they will be looking for, and what they will likely be watching it on.
Straight off i'd say something like DigiBeta would be your first port of call, and any kind of tape format from then on.
DVD i would only consider as a low-end option, along with VCD [which uses mpeg-1].

The best kind of setup i saw for the average joe out there were the old DPS and PAR / PVR cards that stored the files as frames and played them out correctly (through YUV/BNC outputs that we could hook a Beta deck straight into) - without ever putting them through a movie file format or compression [i think there was a little colour spacing squeeznig but i cant remember what it was, and the jobs we did went straight to broadcast and no-one had a problem].
I have no idea what the equivalent is now these days as we usually just give the frames on hard drives or something to a HD suite or something and get them to dump onto DigiBeta.

Partial solution:
somone has posted this already in this thread and it looks like it got overlooked - and wouldve partially solved [i think] the banding problem in the thrusters/exhausts etc on Luc Bessons' 'The Fifth Element' DVD -
and that is the addition of noise - nothing major but enough to 'force' the encoder to look at the data a little more clsoely, and force it to see that there is data variation in what would otherwise be 'smooth' (and therefore cut out) areas of the frame, and so it will encode with more information in that area, hopefully killing the banding issue.

if i had more time i'd do a comparison for you but we're al ljust dumping onto Digibeta here via a HD quite which is fine enough for us.

hth
and hope i didnt step on anyones toes or get anything blatantly wrong :)

Silkrooster
11-05-2004, 04:07 PM
Well I guess I need to reword what I was trying to say. Some programs can not handle 32 bit files, and some can not handle compression. I was not even referring to lossy vs lossless type of compression at all. Targa 32 bit files are 24 bit files with a mask. The only way a targa would be 8 bit is if you converted to 8 bit first then saved as a 24 or 32 bit file. This conversion to 8 bit will cause banding. 8 bit files do not have enough color information to generate gradients with out banding. 8 bit files only have 256 colors to work with. Whereas 24 bit files have millons of colors.
Targa, psd, tiff normally use lossless compression. Jpg, mpg use lossy compression. Any image format that uses a lossless compression can be recompress. However lossy compression can not be recompress otherwise more data will be lost.
AVI, MOV and WMV can be either lossy or lossless depending on the codec.
Silk

Cunhambebe
11-05-2004, 04:25 PM
First, I'd like to thank everyone who took time to respond.
Editing, resizing and re-encoding demuxed VOB files (m2v) as MPEG2 causes banding. Re-encoding VOB files as MPEG2, previously turned into AVIs with a prog called VOB2AVI, causes banding too (despite the fact AVIs look so good, with no banding at all).
Well, I guess MPEG2 is not a perfect kind of file. I'm used to saying it's MP3's brother. Trying to enconde a WAV file as MP3 at 128 kbps is almost the same thing = loss of quality.
At that time, trying to re-render MPEG2 files, it was an already compressed file and GOD knows at what bitrate. But now, it is something different. A band-new AVI file rendered with Lightwave and re-rendered as MPEG2 at the highest possible bitrate. It's very disappointing to find out that MPEG2 is definitely not a perfect format. And it's curious to see a lot of users at Sony's forum and at Videohelp, stating that now, MPEG2 (DVDs) is perfect to store your "movies" for the near future. On the other hand, I doubt most users store their files, movies, or clipps as AVI because I guess it's not comfortable buying HDs all the time you're out of room. Take Sony Vegas example. Vegas is one of the best video editors, but I guess despite the fact it renders as Quicktime and AVI, most people use it to render their projects as MPEG2. It's Dolby Surround System is conceived to work with AC-3 files, and these ones comes along only with MPEG2 files on DVDs. What I'm trying to say is that most "commom" users, render their "movies" as MPEG2. That's why trying to render the whole stuff as AVI is useless, because no one but big enterprises can afford countless HDs all the time. So unfortunately, we've got to cope with our MPEG files.

Lightwolf:
Well, if you care to re-render, open the Effects->Processing, Increase the Dither Intensity and may be turn on animated dither.
-I'll try to do it. Thanks a bunch.

If you have a comp tool, add some grain...
-I'm a newbie, what's a comp tool? Vegas Video Editor has a Plug-in named Film Grain. I was testing it with my file and the results are getting good.

May be the colour conversion from RGB 8 bit to YUV 8 bit (plus the reduced chroma sampling, as was mentioned before) plays a role here as well.
-I did some dithering this way (adding some more color and brightness/contrast), but the file looks totally different form the original.
(I use TMPGEnc and so far never had any banding).
-Excellent choice!

[email protected]:
IMHO it appers that mpg2 is not a suitable format ...It's basic definition includes a limited colour space or palette ...Uncompressed avi (or VT) for short term storage - but most people cannot find enogh HD space to use it for archive purposes and end up backing to some form of video tape, proper digital video is out of reach of most budgets, I compromise on sony DVCAM - which does still have a limitation in colour space, but is a vast improvement on VHS, and certainly on mpg2.
-I don't see many people saying, hey take my mini DV tape here and take a look!(no offense here) On the other hand, it's a nice option for storage as you have well remarked. Thanks for the input!
For 'transmission' you just have to go for the best compromise of file size for the job in hand - fit the compression rate to the capacity of the distribution medium - that's why I use DivX.
-Thanks, I'll try to download this codec....I guess it can be found at videohelp, can't it?

cgbloke2004:
-Thanks for the amazing explanation, fella!

Look at any commercial DVD with a fair amount of CG in it -
Luc Besson's 'The Fifth Element' might be a fair examplehere - usually regarded as a pretty good standard of picture quality vs compression - look at the exhausts from the spaceships - lots of banding.
-They may have compressed it at a low bitrate; the BBC series Blue Planet is another good exemple; lots of banding can be seen as soon as you have dark scenes as sunrises, the depths , etc...Some banding are so worse that can be detected even with a regular TV set.

solution?
keep rendering to uncompressed file formats as you have done, and then keep it that way - buy up lots of hard drives to store them on..
-You must be kidding. :p

Partial solution:
...is the addition of noise - nothing major but enough to 'force' the encoder to look at the data a little more clsoely, and force it to see that there is data variation in what would otherwise be 'smooth' (and therefore cut out) areas of the frame, and so it will encode with more information in that area, hopefully killing the banding issue.
-Thank you very much, that's what I'll do.

Silkrooster:
Well I guess I need to reword what I was trying to say. Some programs can not handle 32 bit files, and some can not handle compression. I was not even referring to lossy vs lossless type of compression at all. Targa 32 bit files are 24 bit files with a mask.

Thanks for correcting....but I thought Targa 32 were 8 bit files.
Now, may I ask you something: WHEN I CHOOSE TO RENDER IN LIGHTWAVE AS RGB, AMONG ALL THOSE FILES, WHICH ONE SHOULD I CHOOSE??????????? I MEAN, THE ONE THAT'S AN 8 BIT FILE..........WHEN I CHOOSE SAVE RGB WITH LIGHTWAVE, I DON'T SEE ANY SCREEN POPPING UP TELLING TO CHOOSE THE CODEC. HELP WILL BE GREATLY APPRECIATED. I'M A NEWBIE :D

Well, unfortunately I'm not George Lucas. If I were George, I would print each Targa on 35mm film. That's a good choice to keep your files for the near future.
Thanks to all!

Silkrooster
11-05-2004, 05:45 PM
To my knowledge LW will render to 24 bit and higher. Some one correct me if I am wrong here. But I did not see anything listed. Is there a reason why you would want to render to 8 bit. Like I said earlier that 8 bit files will cause banding. An example of 8 bit file is the gif format. If you get a program to create animated gif's you will know exactly what I mean.
There are several progams available that can batch convert files to other formats as well as between 1,2,8,16,24,32 and 64 bits.
A greyscale image is also an example of 8 bit. It will show 256 shades of grey.
I have not heard of any programs that have problems with 24 bit uncompressed. I am sure they exist, but rare.
A cheap program you could get, is Apples Quicktime. Pay for the license, then you can use the extra features it provides. For example, you can import a sequence of images and export to mov, avi, flc. Quicktime provides codecs that can reduce the number of colors to 256. Also the flc format is an 8 bit format that is hardly used any more. I think the license is around $20-30. This is also nice if your video editor can't import stills.
Some image editors call 8 bit images "palleted" meaning a pallet of colors. If you do convert to 8 bit, make sure you optimize the color pallet. If you use the system colors pallet or a web brower pallet, you images will look like crap.
Silk

Cunhambebe
11-06-2004, 07:16 PM
Thanks for taking time ... to respond.

Is there a reason why you would want to render to 8 bit. Like I said earlier that 8 bit files will cause banding.

Now, I am a bit confused. Some people told me that MPEG2 compressors can't get all that 24 bit and that's why I've got some banding here. An user at videohelp wrote this:

Targa 24 is 8 bits each of red, green, and blue. Targa 32 is the same as targa 24 with the addition of an 8 bit alpha channel.

Now you say that 8 bit files cause the banding. Anyway, some other users suggested this:

-please check it out at http://www.videohelp.com/forum/viewtopic.php?p=1093459#1093459

BJ_M and I both gave you the solution: add noise to your renderings (some programs refer to this as "Film effect" because it simulates film grain). It's best done in your 3D program while rendering.
If you can't, or don't want to do it while rendering do it as you convert from TGA to MPEG. If you don't like that solution use a lossless AVI codec (uncompressed, HuffYUV in pure RGB mode, PicVideo's lossless MJPEG). You won't get any/much compression but the output will be exactly the same as the input.

I just disagree with that part...rendering as AVI uncompressed; MPEG2s this way are much darker than the ones that come from Targa sequence files.
Anyway, I guess the solution has already been found here....

Partial solution:
somone has posted this already in this thread and it looks like it got overlooked - and wouldve partially solved [i think] the banding problem in the thrusters/exhausts etc on Luc Bessons' 'The Fifth Element' DVD -
and that is the addition of noise - nothing major but enough to 'force' the encoder to look at the data a little more clsoely, and force it to see that there is data variation in what would otherwise be 'smooth' (and therefore cut out) areas of the frame, and so it will encode with more information in that area, hopefully killing the banding issue.

I really hope this helps other newbies and some other experienced users who are having the same trouble with MPEG2 files.

Thanks a bunch folks!

Silkrooster
11-07-2004, 12:27 AM
I read some of the other post on that forum, and I can see why your a little confused. Your getting conflicting information. The file formats you see listed in Lightwave have numbers after them. They stand for the bit rate the file is going to be saved as. Therefore targa24 will be 24 bit and targa32 will be 32bit. What maybe confusing is some people are talking about 8 bit channels. A channel is like a layer that color information is stored. For example an RGB image file has three channels r, g, and b. Likewise cmyk has 4 channels. Each channel stored 8 bits of information.
So on a targa 24 bit image you have 8-bits or 256 shades of red, 8-bits or 256 shades of blue and 8 bits or 256 shades of green. 8+8+8=24 bits or 256X256X256=16,777,216 colors
To complicate this you can also have another channel for alpha information which will add additional 8 bits or 256 shades of grey. If you use cmyk then you have 8bits for c, 8 bits for m, 8 bits for y and 8 bits for k. 8+8+8+8=32 bits +8 bit alpha = 40 bits. Unless your planning on printing we don't need to worry about cmyk.
Now for the MPEG 2 file format. Think of it kind of like jpg. They are sorta related. It will take a 24 bit image and scan it for areas of solid color. It will then delete all of that data and replace it with a single color value. It then goes further by looking at the frames before and after that frame. It then deletes any frames that are identical. I beleive it goes even further, but that is as much as I remember.
So those that posted and told you that by adding noise to your scene, they are right in the sense that when you encode to mpeg the encoder will see varying information and won't discard that data. So less banding would occur.
Silk

Cunhambebe
11-07-2004, 10:44 AM
Thank you very much for the valuable help, Silkrooster. Now I understand. Thanks again. :D

Lightwolf
11-07-2004, 11:10 AM
Yeah, I guess the x-bit discussion can be confusing...
In general, in most discussions I've come across the number of bits is the number of bits per channel. But a per channel / per pixel definition can help.

So, from least _total_ bits upwards:

1 bit -> black & white
8 bit -> usually mentioned as grayscale
anything in between can be a colour image with a well defined palette (like .gif), which can use anything between 1 and 8 bits to use 2 - 256 colours.
10 bit -> is per channel and either points to 10bit YUV data used in high end uncompressed video boards, or 10bit RGB data used in cineaon/dpx for film processing.
16bit -> definetly defines the number of bits per channel, except concerning old esoteric file formats (another exception: VUV 4:2:2 is 16bit/pixel.). Nowdays this can either be 16 bit integer (.tif) or 16 bit float (openEXR)
24bit -> always seems to point to RGB at 8 bit per channel.
32bit -> usually points to RGBA at 8 pit per channel, can nowadays also point at 32bit per channel and in this case refers to float, not integer (again, openEXR, as well as most HDR formats).
48/64bit -> again refers to 16bit per channel, integer formats in RGB(A), such as the .sgi format that LW can save to.

...yeah, it's a confusing world out there, and having different bit depths, as well as colour spaces, doesn't help either ;)

Cheers,
Mike

Mylenium
11-07-2004, 12:47 PM
Well, some points that have been totally lost are as follows:

a) DVD compliant MPEG II uses a 12 frame GOP (group of pictures) in the order IBPPIBPPIBPP. I-frames are "key frames", all others only contain differential info to reconstruct inbetween frames. This means only every 4th frame is an actual image which can hold up on its own.

but:

b) I-frames apply intraframe compression based upon a fixed block pattern similar to JPEG, so even they contain already crippled information.

If you consider this as well as the limitations already mentioned by others, you will see that MPEG II is useless for quality "storage". Even if you had infinite data rates you would still lose information.

Let me just add one more comment. All this babbling about the best encoder is kinda pointless. Mostly it's simply a matter of preparing your files the right way and how much time you have. In a production environment there is always a compromise between quality and speed and TMPEG isn't really famous for that. With a looming deadline ProCoder, MainConcept or hardware based approaches beat it every time.

Mylenium

cgbloke2004
11-08-2004, 10:21 PM
glad to be of help to you Cunhambebe!


[I]Look at any commercial DVD with a fair amount of CG in it -
Luc Besson's 'The Fifth Element' might be a fair examplehere - usually regarded as a pretty good standard of picture quality vs compression - look at the exhausts from the spaceships - lots of banding.
-They may have compressed it at a low bitrate; the BBC series Blue Planet is another good exemple; lots of banding can be seen as soon as you have dark scenes as sunrises, the depths , etc...Some banding are so worse that can be detected even with a regular TV set.
You are correct there
- also something else perhaps to think about - different colours have different responses - i cant remember at the moment but to the human eye it is banding in red or green is less obvious to the human eye than banding in blue.. [which would explain why the blue areas are more obvious when banding is present]
So you can get away with certain areas and not with others..
Someone else will probably correct me on this..


[I][I]solution?
keep rendering to uncompressed file formats as you have done, and then keep it that way - buy up lots of hard drives to store them on..
-You must be kidding. :p
hehe :) its a partial solution for storage. With the cost of hard drives so cheap these days, it is quite easy to back up your data on 120gb drives now [which is what i do..] - i use removable caddies and dual-bay external fireware cases - i can just swap out whole hard drives as and when i need.


Now, may I ask you something: WHEN I CHOOSE TO RENDER IN LIGHTWAVE AS RGB, AMONG ALL THOSE FILES, WHICH ONE SHOULD I CHOOSE??????????? I MEAN, THE ONE THAT'S AN 8 BIT FILE..........WHEN I CHOOSE SAVE RGB WITH LIGHTWAVE, I DON'T SEE ANY SCREEN POPPING UP TELLING TO CHOOSE THE CODEC. HELP WILL BE GREATLY APPRECIATED. I'M A NEWBIE :D
i've used Lightwave for years, and i pretty much use "LW_Targa32" all the time.
24bit colour file with 8bit space for alpha information, and lossless/uncompressed so its as good as it can be (without being a hdri/96bit data image perhaps..?). Most other systems will accept this format with no problems.
Theres no need to worry about codecs etc when choosing a file format such as this.

hope that helps!

Cunhambebe
11-10-2004, 02:56 PM
- Lightwolf and Mylenium;
Thanks for your help..

- cgbloke2004
Donīt know what to say...Thanks so much for the valuable help. Thanks for letting us know the way you store your files (despite the fact SATA HDs are just a bit more expensive :p ) and thanks for the info on banding. Thanks to all who helped! :)
Hope this topic can help other users too!!! Iīm sure it will

lardbros
02-12-2005, 09:05 AM
By the way Cunhambebe i've just realised and have wondered why my mpegs are darker than my rendered stills..... check out your display settings, if you have an Nvidia like i do there are settings for your overlay video. My mpegs and avi's had always been darker than they were on other monitors and even my TV. Just raise the brightness of your overlay video and it will do the job fine... my monitor now displays exactly what everyone else will see brilliant!

starbase1
02-14-2005, 03:54 AM
Well, for those of us without infinite disk space...

I have recently been getting the best results ever by the following method:

a) Render to LW Jpeg sequences.
b) Compile these JPEG's into vid using Adobe Premiere Elements, (nice and cheap!). I use the PAL DVD standard setting in Premiere.

I just can't get animation quality like this direct from LW.

The level of compression in the JPEG is so much less than that in the video, it really does not show.

I'm still curious as to why AP produces better video - maybe it's the codec, in that case parhaps I can hook the codec up to LW, and get the same quality (or better giving the lack of the JPEG stage).

Nick

lardbros
02-14-2005, 04:02 AM
WOW does premiere now have a DVD setting? I might have to upgrade!! But still you are dead right about getting better results using Premiere than most other software. I've even tried Digital Fusion here at uni and the results are pants to be quite honest... don't know what i'm doing wrong, but Premiere with 32bit .TGA's and just DIVX 5 or even mpeg4 v2 gets loverly pin sharp results! yummy!

Just out of interest, i'm doing a render that is going to be projected onto an 8ft by 4ft projector: what resolution would i need to render at to achieve the best results? I guessed that projectors only process television resolutions anyway so normal PAL would be okay... or would the higher the resolution be better for it? It's going to be played directly through a PC too!! Any help would be incredible!

starbase1
02-14-2005, 07:06 AM
Yes, premiere elements has a DVD setting. I find the prog very arcane to use, particularly using the effects - and the DVD menu building is DIRE!

But the quality of the DVD format output is excellent. It seems to be doing a fine job of removing flicker from fine lines and the like. And as it is DVD ready, you won't be recoding later...

The price is very sweet too.

As for your projector question, seems to me the key thing is not the size it projects to, but the resolution it goes in at. If you render to exacxtly this size there will be no on-the-fly resizing. If the people owning the projector don't know, get them to tell you the make and model and look it up.

Nick