Transparent AVI?

lnetzel wrote on 8/7/2003, 1:06 AM
I asked this at www.dvdrhelp.com and did'nt get a single answer so I'm trying here!

From what I understand an Uncompressed AVI is bassivally 25 BMP pictures per second at PAL, right? Is that what's called HD by the way?

So why can't anyone do a codec that would use PNG pictures instead and make it possible to actually do tranparent AVIs? Or is there no need for it?

Comments

Grazie wrote on 8/7/2003, 1:34 AM
Errmmmmm . .. not quite sure I understnad what you are asking . . . Are you wantin an AVI that has PNGs in it? And that those PNGs are transparent? I use this process all the time. I can import PNGs and "see" the underlying video . .. this can't be what you are asking? As to CODECS, again I'm way off here. Others will/might have a stab at it for you.

Can you explain, in more detail, what you are attempting to achieve - I find this is often a better place to start from.

Hang on in there - loads of experience here . . . .

Kind regards,

Grazie
lnetzel wrote on 8/7/2003, 2:05 AM
Hmm.. I thougth I explained it pretty well... but okay!

I dont' mean an uncompressed AVI is specifically bulid up of BMP's cause I have no idea how AVIs work in technical detail but in PAL there are 25 images per second and the least compressed format when it comes to windows and images are BMP, right? so I figured an avi is bulit up of images like BMPs maybe... Why I draw this conclusion is because someone once told me that the MJPEG codec uses JPEG pictures... so... the comparision to BMP is logical for me.. but maybe that's not how I am supposed to look at an avi...

Anyways... then I figured... If it's possible to make a codec that will "glue" together PNG pictures with the Alpha channel thingy, would'nt it be possible to make an AVI with a transperant background then so you wouldn't have have to mask certain colors and stuff?

For example if you export a 3d animation from 3ds MAX with a codec like this you would save time a troubles with the masking...

I noticed this when I imported a tranarent GIF animation to see if it worked and it did.. but I'm not gonan use GIF to do these things... :)


Grazie wrote on 8/7/2003, 2:28 AM
lnetzel, apologies for being such a dunce on these matters. It will mean a lot to other well honed techies. But me! The second way you explained it has sunk in. BUT, I don't have an answer - don't do much animation.

However, even with my little knowledge/experience with this stuff - I do think you are onto something - I really do . . .. .

I suppose chroma key aint the way you want to go? Apologies again, if this isn't what you want to hear . . . maybe you are asking a very technical question rather than wanting a "fix". Yes, I understand the bit about saving time . . ..

I do like your thinking processes - a sideways view to things is always a "lure" for me. May you always do this. This is where the interesting and creative stuff happens. My only thoughts - small as they are, on all things animation - one would still need to "trannie-up" each separate BMP or PNG or JPEG. Or am I missing it again? Then onto the CODEC thing. Neat idea!! How this could stich - phhaawww maybe a 10,0000 frames . .. is truly an interesting thought . . ..

I shall keep reading this thread with much interest.

Grazie
farss wrote on 8/7/2003, 3:16 AM
I think the biggest issue trying to do this is ending up with a truly enormous set of files!

I can see no reason though why you cannot stitch any number of PNG files one after the other into VV and have it render the whole thing out as an AVI file or whatever. VV will respect the alpha channel information in PNGs, in fact PNG is a much better format than BMP, it uses lossless compression so your file sizes are kept managable and it has 8 bit alpha channels, you can export to AVI with transparency if needed but I's suggest assembling the whole thing in VV even if just to see how its going to look.

You can print out to DV to proof and if you wanted to go to film once you've got all the stills together send a very big disk off to have the stills printed frame by frame. Alternatively you can export uncompressed HD and send that off s far as I know.

I don't know if this really addresses what your asking but you've got the right idea, video is only 25 still images per second!
lnetzel wrote on 8/7/2003, 3:34 AM
NO you missunderstood... what I want is a AVI with a codec that will support transparancy... like GIFs or PDS! I dont' mean Glue PGN togehter litterarly... I mean it as if the AVI would sort of be a bunch of PNGs. So that when you import the clip in vegas and you put it over another clip the background will be the clip underneath.. without having to mask anything...

Grazie wrote on 8/7/2003, 4:36 AM
" . . . would sort of be a bunch of PNGs" - Ah hAH ! Got it!

So what I interpret you asking for is that the "Avi" would be transparent to the clip underneath it on the T/L? Do you mean a type of double exposure? - Please don't burst a blood vessel - I'm trying to help and understand - honest . . !

. . with head covered wearing a builders hat . . . - Grazie
lnetzel wrote on 8/7/2003, 4:40 AM
Yes! Exactly... an AVI codec that supports transperancy! I would like that!
Grazie wrote on 8/7/2003, 4:50 AM
Okay . . I think I'm getting it now . . So, Are you after a type - AND I CHOOSE my words carefully now . . . - a type of "Double Exposure" - is that it? Are you wanting Track 2 vid to show thru' Track 1 - is that it?

Not cowering so much now . .

Grazie
farss wrote on 8/7/2003, 6:48 AM
Unless I'm mistaken VV can export an AVI with transparency.
Many digital video standards can incorporate transparency including HD.

No problems doing that, but as far as I know you can only do that going out, there is no transparency in nature for a camera to capture. So unless you're talking about transparency create in an artificial way such as chroma keys or through graphics I don't quite get what your looking to do.

Sorry if I seem a bit thick, I know you have some great idea in your head, just need to find a way to communicate it to the rest of us.

Grazie wrote on 8/7/2003, 6:58 AM
farss, this was my thought process too. As you say, Inetzel does have an idea, if we knew what was trying to be attempted OR understand the nature of AVI's and their "transparency" qualities, I too am a little lost. C/K will give a tranparent area to a clip allowing over stuff to show through. Otherwise, as you say, when film is taken and then captured it is chock full of data from top to bottom. Colours - yes; Contrast - yes - Grain - Yes. But tranparency - how would this occur? Where would one use it? The good thing about knowing "little", like myself, is that I can respect an idea that may, just may have an element of a brilliant idea within it. . .

C'mon Inetzel . . give us more of a clue . . .

Grazie
sdmoore wrote on 8/7/2003, 7:07 AM
Hi Inetzel,

If you're wanting to generate an avi from 3DS Max then make sure you select uncompressed as the codec and 32bpp as the colour depth. 3DS should then create an avi with transparency that should work in Vegas (you may need to manually go into the clip's properties in Vegas and tell it to use the alpha channel)

Cheers,

Scott
Former user wrote on 8/7/2003, 7:25 AM
You can create an AVI using an Alpha channel by createing an Uncompressed AVI. when you render in Vegas, if you use an Uncompressed option, you see a check mark for Retain Alpha channel.

Alpha channels are not supported in any compressed format.

Quicktime Uncompressed is a common format used with alpha. Indeo also supports a transparent color.

Dave T2
farss wrote on 8/7/2003, 7:26 AM
Grazie,
I just read his original post and maybe that's really all he didn't understand, that AVIs can have an alpha channel. Beyond that its a bit of a mystery unless as sdmoore seems to think he's trying to ouput from some 3D program and preserve transparency.

Maybe I'm getting too old for this or is it just that I'm hopeless at cryptic crosswords.
lnetzel wrote on 8/7/2003, 7:45 AM
Aha.. I guess I got my answer now.. an Uncompressed AVI can save the alpha channel.. then a codec for this won't be nessessary... unless you wanna talk about diskspace.. but Great, now I know, never really use the uncompressed format before actually...
Grazie wrote on 8/7/2003, 7:49 AM
Hey we got there! Open the beers and let's chiillllllll out - Temp in London has dropped to a chilly 33ºC.

lnetzel, now what are you goning to do with it? - That's what I wanna know - please.

" . . now I know, never really use the uncompressed format before actually... " please finish this sentence . . . . . wink!!

Grazie
Former user wrote on 8/7/2003, 7:55 AM
Size usually isn't an issue because of the most common use of an Alpha Channel is related to graphics. Most graphics I have used are only a few seconds.

I have created animated logos using software like Cool 3D. Export a Targa sequence from that and import into VV. Then create an Uncompressed AVI of that Sequence, now you got a logo treatment that can be saved and used on several projects quite easily. It doesn't restrict you to avoiding a color, like chroma key, and gives a clean key.

Dave T2
lnetzel wrote on 8/7/2003, 8:04 AM
An example to make you understand what I mean..

If I in a 3d program make a walking MAN.. just the animation of walking... nothing else, just the man and a transparent background then I want to be able to export the animation and then putting in over a background I made in vegas and then I will not have to bother about the background.. since I now can export uncompressed AVI from 3dsMAX I won't have to deal with masking.. Chroma Key and that stuff...
Grazie wrote on 8/7/2003, 8:06 AM
Excellent - now I understand.

Grazie
Former user wrote on 8/7/2003, 8:10 AM
I don't know if 3dsMax supports it, but it probably does, you can export a Targa or Png sequence with alpha. This will save a series of individual frames. Then VV will allow you to import the sequence as a single file with alpha.

Dave T2
BillyBoy wrote on 8/7/2003, 8:51 AM
Hmm... how about a silly little cartoon character of me trying to dance as an example?

Go to Kelly's site and look at the first few seconds of me "dancing"

http://www.vegasusers.com/vidshare/textdisp?billyboy-pretender

My alter ego was made in Poser. I set the background to a ugly color I know wouldn't be in the finished file exporting as a avi. I then dropped it in Vegas as a overlay then used the chroma key filter to select the background color out and then threw in a series of Bryce backgrounds. Total project time about twenty minutes, just messing around so it little on the crude side, but you get the idea.
Grazie wrote on 8/7/2003, 8:57 AM
Thanks BB! Forgot how Handsome you looked - AH HAHA AHAH!!! Grazie
lnetzel wrote on 8/7/2003, 9:07 AM
That was some exellecnt sound manipulation... cool!
sdmoore wrote on 8/7/2003, 9:32 AM
Hi Inetzel,

Glad you got it sorted!

Yes, the downside of uncompressed is large files. I have seen that the huffyuv codec has an option for encoding using RGBA (24bit RGB + 8bit alpha) but it doesn't seem to work for me. Has anyone else managed to get it to work?

I've got the source code kicking around somewhere - maybe I'll have a go at fixing it when I've got some spare time.

Cheers,

Scott