Does Premiere Recompress avi Files When Doing Transitions?

[Zeek]

Hello...

Having been on the scene for a while now and getting a nice, healthy love-hate relationship going with video and all the time it consumes, I decided it's time I finally started playing around with Adobe Premiere a bit. So far, it's quite a bit easier than I thought, but one thing is stumping me:

When combining very large (V-Dub filtered) avi files and setting transitions in between them with Premiere, the resulting file size is much smaller than the sum of the two parent file sizes - and since I am saving stuff as uncompressed (or so Premiere tells me), this is confusing me. For example, after taking two files with a total size of about 1 gig, combining them and adding a transition, I'm getting a new file of about 270 MB in size - which is about what I started with before filtering. Great for hdd space, but my concern here is that too much back and forth with compression will be affecting the quality of my final work by the time I get to encoding for DVD.

From start to finish, what I've been doing is transferring from DV, filtering with V-Dub (which creates a much larger file size) and then adding desired transitions and effects prior to encoding to MPEG 2 for DVD. Normally, with this stuff, I would frameserve, but the new Adobe toys that have caught my eye are keeping my attention (and hdd space) for a while. And that is that.

Am I missing something here? I'm well aware of what happens with V-dub when applying filters, but the re-shrink caused by Adobe is really concerning me and, having been burned before, I've got the whole show on hold over here until I figure out what's what.

Muchas gracias to anyone that can help...

Zeek

[Zeek]

Also:

Prolly not related, but I am also noticing a few problem-child frames that are showing up (Post-Adobe) here and there. They are few and far between, but green flicker that is showing up on the white colors when it does happen is very annoying. That, and I'm also getting the occasional static crunch here and there - also post Adobe.

Dammit. New toys always come with a cost that's way past the financial. Bleechh...

[guns1inger]

Any time new footage is created, it has to be encoded (unless the results are to uncompressed output). It seems obvious to me that the output here is being encoded to some degree. As what, only you can tell. If you can't work it out from Premiere, use the latest g-spot to find out what's going on. Based on the before and after sizes, it sounds like it is probably DV output.

There are a couple of things you could do to make your own life easier. You could use avisynth instead of virtualdub, and therefore frameserve directly to Premiere. You could also install the Debugmode Frameserver so you can frameserve from Premiere to your encoder (assuming it is not the Adobe Media Encoder)

[daamon]

From start to finish, what I've been doing is transferring from DV, filtering with V-Dub (which creates a much larger file size)...

Am I missing something here?

It sounds to me like, when you're saving your filtered AVIs in VirtualDub, you're not telling VirtualDub to use a DV codec (the Panasonic DV Codec works well with VirtualDub, and is free) so it defaults to uncompressed AVI - explaining the much larger file sizes. Let me guess... about 5x bigger?

I'm well aware of what happens with V-dub when applying filters, but the re-shrink caused by Adobe is really concerning me...

So the "re-shrink" you think your getting is actually (if I'm right) going to be Premiere taking (now) uncompressed AVI and converting it to the format it's designed to work with - DV AVI.

So, in fact, there's no re-shrink - it's more a case of unneccessary inflation after VirtualDub instead of a worrying shrinkage in Premiere.

Solution: Download and install the Panasonic DV Codec and set this in Video -> Compression, and make sure you're working in Video -> Full Processing Mode.

[Zeek]

@ guns1inger:

We meet again.

Sorry...I was not clear. The (dramatically) increased file sizes are a product of V-dub only - and not Premiere, where the "new" footage is being created. When using filters in full processing mode, this is what is happening to me every time. With my very limited knowledge of frameserving, my understanding was/is that, in addition to saving yourself a step, the whole point of it is to save the huge demands on additional disk space, as well. For some odd reason, I wasn't aware that compression was an option when using full processing mode with V-Dub, had it in my head that filtering meant huge disk space, and that was that. So, although what you are saying about encoding to some degree does make sense, I'm sure the un-necessary inflation daamon is talking about is probably my problem in this case.

As far as G-Spot and identifying the codec go, though I'm not where I can verify it 100%, I'm 99% sure that what I'm ending up with from Premiere is using the default Micro$oft DV codec.

And lastly, with regard to frameserving, Premiere, and avisynth - I will definitely look into that stuff. With my timeline, very limited grasp of framserving and Premiere and almost no knowledge (other than the real basic, rudimentary stuff) about avisynth and scripting, however, it'd probably be best to read up on that stuff now and give it a try on the next go-around. On avisynth, especially, I'm a real first-grader so, if you have any recommendations for required reading, I'm all ears.
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@daamon:

Well, I feel smart. If you read my above post to guns1inger, you'll see that I wasn't aware that compression could be used with full processing mode in V-Dub. Thought I knew that program pretty well, but guess I didn't get enough past the default settings to realize this and will now have my humble pie. Though I can't verify the 5x increase exactly at this moment, that sounds just about right and, in any case, the new stuff is damn sure a whole lot bigger. My suspicions are that a 5-fold increase is a very solid estimate though and will check/re-post later on that.

What you are saying about unnecessary inflation and what Premiere is doing with all of this is definitely making sense. I will grab that Panasonic codec after finishing my pie and get cracking on this.

Meanwhile, another question for you: Hard drive space notwithstanding, do you think I'd be better off trying to keep what I've done and then pick up from that point using the new codec, or should I re-filter and start the whole damned thing from square one? It's tempting to try to keep what I've done so far but, again, I'm not sure whether or not the inflation issue will result in quality loss or problems somewhere later on down the line. And with the kind of time I've sunk into this already, believe me, I'm not going to be into getting any new, nice little surprises.

On that same note, you may have noticed that my last post said something about "problem-child" frames and an annoying static sound, both of which are popping up on Premiere's finished product, after transitions are made. Basically, I'm seeing an annoying green flicker, with certain colors (reds and whites, skin tones) taking on a strong hue in some of the frames, and also some loud, annoying static sounds. Re-rendering results in the same problem, though the location it appears in will usually differ. The visual stuff is very intermittent, but definitely there enough to be noticeable and annoying and the static is obviously intolerable for what I'm trying to do. This happens only when transitioning with these huge, gonzo-sized files inside of Premiere. I doubt that, with Premiere working with my kind of harware (I can land the space shuttle from my room) , that I'm giving the system too much to work with - but you never know. Think the Panasonic codec and compression might fix this?
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Thanks to you both. Very helpful and informative, you guys. If you're ever in Albany, NY...I'm buying.

[mikiem]

FWIW, I don't understand if you're using prem, why not just use prem at the start on your DV footage. Also, I thought prem installed it's own DV codec, & think I've read of some prob. between it and the pana version, but that's a big maybe.

Other stuff to look into if you want, new V/Dub has some changes re: internal DV codec.

[daamon]

@daamon:

Meanwhile, another question for you: Hard drive space notwithstanding, do you think I'd be better off trying to keep what I've done and then pick up from that point using the new codec, or should I re-filter and start the whole damned thing from square one? It's tempting to try to keep what I've done so far but, again, I'm not sure whether or not the inflation issue will result in quality loss or problems somewhere later on down the line. And with the kind of time I've sunk into this already, believe me, I'm not going to be into getting any new, nice little surprises.

Ordinarily, I would say going from DV AVI to uncompressed AVI and then back to DV (as, it seems, is what's happening with you) wouldn't be a problem. However, the "green flicker" and other artifacts you're seeing may be as a result of this. I'm not basing that on any technical knowledge - just a hunch. Maybe a trial of filtering and using the DV codec to see the results is worth while - use a clip of about 10 minutes long.

On that same note, you may have noticed that my last post said something about "problem-child" frames and an annoying static sound, both of which are popping up on Premiere's finished product, after transitions are made. Basically, I'm seeing an annoying green flicker, with certain colors (reds and whites, skin tones) taking on a strong hue in some of the frames, and also some loud, annoying static sounds. Re-rendering results in the same problem, though the location it appears in will usually differ. The visual stuff is very intermittent, but definitely there enough to be noticeable and annoying and the static is obviously intolerable for what I'm trying to do. This happens only when transitioning with these huge, gonzo-sized files inside of Premiere. I doubt that, with Premiere working with my kind of harware (I can land the space shuttle from my room) , that I'm giving the system too much to work with - but you never know. Think the Panasonic codec and compression might fix this?

See my comment above. Oh, and a for the "land the space shuttle from my room" comment...

What filtering are you doing in VirtualDub that can't be done in Premiere, like mikiem says?

[Zeek]

mikiem:

Guess I skipped the Adobe from the start business because I'm still very much the neophyte at it, and I'm taking my time getting into the pool. Definitely looks like I'll be having a closer look though, but I've just been using what's comfortable for me for now. God knows that, with the way this project is turning out so far, comfort is at a premium atm.

And thanks for the tip re the V-Dub codec. I will definitely check it out.
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daamon:

My hunch is the same on that flicker business. I'll soon be in the process of trying it out to see if we're correct.

As, for VirtualDub, I'm sure there's nothing it can do that Premiere can't. At this point it's more a matter of what I'm comfortable with. I'm trying to get the hang of Premiere, though.

If I get around to finishing up this other bs with the trial and error later tonight, I'll re-post to let you know what happened.

Been staring at this thing all damned day, now. I think I'll take a break for a while now and go slit my wrist.

Thanks mang...

Z

[daamon]

I'm trying to get the hang of Premiere, though.

Check out: www.wrigleyvideo.com/videotutorial - there's also a very healthy forum there too.

Been staring at this thing all damned day, now. I think I'll take a break for a while now and go slit my wrist.

Ha ha ha... Try not to get any blood over the keyboard - it'll be a b1tch to get out! If you do make it back, check out that link above...

[Zeek]

Hehehe....back.

Yeah, I just found my way over there and it's quite the resource, that little site. Looks like I'll be killing some time with those tutorials, for sure.

Thanks for all the help, man...and Happy New Year!

[Cornucopia]

To answer your original question: YES, every time there's a transition/composite/effect, there will be re-rendering (and recompression if applicable).

The color problems you're getting may be due to an accidental shift in chroma values...

Original footage = YUV 4:1:1 DV compressed
Combined Vdub footage = RGB 4:4:4 uncompressed
Final Premiere fottage = YUV 4:1:1 DV compressed

It will have to approximate (guess) the color values when going from the 1st to 2nd stage, then drop 3/4 of them when going from the 2nd to the 3rd stage, so what values are left may not be true to the original.

You're much better off staying as DV compressed. Coupla reasons:

1. Premiere uses YUV-native processing when dealing with DV source files, but RGB with everything else. You'll run faster staying DV.
2. Since your Premiere sources are currently RGB uncompressed, Premiere has to recompress EVERYTHING back to DV, not just the transitions. This takes WAY longer than staying in DV.
3. Color purity will be much improved staying in the same color space (YUV, as in DV compression) the whole time.
4. Filesizes will be less.

2 ways to do this:
Original DV source files --> AVISynth (works in YUV) --> DV file or frameserve --> Premiere --> Rendered Final DV or frameserve --> Encoder
-or-
Original DV source files --> Premiere --> Rendered Final DV or frameserve --> Encoder

I think it's kinda obvious which is more streamlined...
Time to bone up on Premiere a little more.

Scott

[Zeek]

Good answer, that...

Time to hit the books some more.

[Zeek]

Scott:

After re-reading your post, it seems as if you have a much better than average grasp of this shit and so, if you have a moment, I have a couple of follow-up questions:

1. Regarding the YUV-RGB and back stuff, the ratios (which I have to confess I'm not schooled on, as of yet), and what program works with what kind of stuff, where did you get this information? (Obviously, I can and will google it, but any amount of entry-level edumacation is always helpful.) Any recommendations?

2. Do you think it's likely this same (possible) cause of change in chroma values could be behind some other nasties? I'm working with some pretty poor footage here, and had to resize, rotate, and then crop some of it to tidy it up a bit. The problem is - and this is REALLY weird- that if I do this resize and rotation AND add some of the additional filters I want to add (increased saturation, contrast, etc), I get a nasty "rippling"/distorting effect when the camera is moving, or when one of the subjects is moving quickly and significantly.

This happens only with motion, and only with the other filters applied after resizing and rotation, not with R&R by themselves. I've pretty much messed with and isolated all the filters, all the variables within the filters themselves, and done everything else I can think of EXCEPT re-process the whole thing from the beginning without this uncompression/re-compression trip. Obviously, that's going to be my next step - but man, what a pain in the arse.

Think this might be my problem again?

Guess I won't be forgetting to click that little codec button from now on.

Dave

[Zeek]

Just got home and tried re-filtering a small, compressed (normal DV) clip. And...it doesn't change a thing.

I think VirtualDub's rotation2 filter is causing it. Oh, well....

[jagabo]

It sounds like you are working with interlaced footage. You can't rotate interlaced video without deinterlacing or inverse telecining it first.

[Zeek]

Jagabo,

Yes, I believe mini-DV is interlaced and, dammit, after five years of haunting these forums, you would think I'd have thought of this. I'm sure that this will fix the problem, and thanks...

The question now is, with most of the other filtering already done, can I mix the old stuff with the new after re-rendering the problem footage? My gut tells me that mixing interlaced and de-interlaced stuff is probably not a good idea, but it'd be nice to avoid re-doing the whole ball of sh*t for a grand total of about 40 secs worth of motion. Maybe I could section off the problem footage into it's own chapter and then be able to mix the two footage types without issue?

In any case, thanks again for curing me of a real senior moment. I'd just about thrown in the towel on this...

Z

[jagabo]

Zeek, You should be able to reencode only the problematic section. If the rest of your your video is progressive then encode the rotated section as progressive. If the rest of the video is interlaced reencode the deinterlaced/rotated section as if it's interlaced. There's no problem encoding progressive video as if it's interlaced.

[Zeek]

Thanks again, jagabo. I'll hit only the problem areas then.

Also, did some research in between cases here at work (who do they think they are, interupting me, anyway?) and I found some other good info, along with an area-based (conditional) filter at this site here, if anyone is interested.

Thanks once again for the time and headache saver...

[Zeek]

Hate to beat this thing to death, but...

Just got home from work, ran some test clips, and:

1. You were exactly right. De-interlacing before filtering does the trick. And, more surprisingly...

2. Encoding to standard MPEG-2 also resolves the issue.

Just for fun, I ran the clip through TMPGEnc Plus, as both interlaced AND non-interlaced video, and saw the problem disappear.

Wtf??

Either way, the problem is solved. Just thought you might like to know about the other finding.