AVI - New one on me... (kinda long post, sorry)

So I get this project where I'm supposed to rebuild a DVD for a client who originally was working with someone else. Long story short, they had to make content changes and didn't want to pay the exortortive prices of the company they had originally hired to author the DVD.

Well, their editor had edited the project in Premiere on a PC and had exported all the clips as AVI files. They gave me everything on a hard drive and said I was good to go.

Luckily for me, Compressor recognizes AVI files, so I encoded them to m2v and started to build the DVD. However, there was one last minute change they asked me to make. I was to split up one of the AVI clips into two separate clips so I could manipulate them differently in DVDSP.

I took the clip and converted it into a quicktime file for FCP and imported it to make my edit.

That's when I noticed the peculiarity. The video in FCP looked different than it did on the sample DVD I had been given to compare my work with. There was a luminance shift where the whites were no longer broadcast safe, and the hue had shifted making everything look "redder". I tried to color correct it, but there was a problem. Everytime a graphic element flew over the video (not gfx that I made, but ones that had been put on the original clips by the Premiere editor and exported with the video) there was a seriously noticable shift in chroma, saturation and hue. It looked like a really bad overlay.

When I removed the color correction, the shift (although still there) was far less noticable. I tried everything I could to fix the problem in FCP, but was unable to do so. I concluded that the conversion of a PC AVI file to a Mac quicktime introduced this issue as it was non-evident on both the sample DVD as well as when I viewed the AVI files on a PC.

I took the files to a friend who had Premiere and imported them. Then I exported the files from Premiere into the quicktime format on his PC. When I got them back to my mac, viola the shift was no longer there.

Is there something wonky with quicktime or compressor's transcoding when dealing with files that originate on PCs? Has anybody had issues like this, or knows a good workflow dealing with AVI files so that I can build this DVD without changing the video levels all over the place?

Andy

Hi Andy

All kinds of filetypes can have weird shifts when converting them to other formats, like going from 4:4:4 10Bit uncompressed to 4:1:1 8bit DV you will lose loads of colour information which is most noticable in smooth graduations... or from DV to MPEG-1 I often find a massive shift, which I need to minimise by altering the Gamma by +30% & Brightness +5-10% & Contrast+5-10%

Anyway...

If you get files from the PC in future - tell them the exact QT format you require rather than windows AVI - this way you'll avoid the conversion time as well!

If this is not possible, the best thing to do would be for the Editor to playout to tape from Premiere (hahahaha tell them good luck when they do! Sorry I don't do PC's for various reasons but the unreliable nature of video on a PC is one of them!)

Then just digitise the tape into FCP.

Just to check - are you both using DV? If so then the file won't suffer going from PC-DV-Mac via firewire.

If you are using an old analogue format like beta sp, then make sure they playout colour bars for you to calibrate the input, or at least adjust the file, once in FCP.

Hope this helps

Ben





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Thanks Ben,

I know that you get color and luminance shifts with different codecs (ie: the DV to MPEG 1, or uncompressed to DV) but the reason this was unexpected was because it was DV to DV. Essentially all I was doing was removing the AVI wrapper and putting it into Quicktime; I didn't change the codec. Unless of course the DV codec produced in Premiere is different than the DV codec produced on a Mac.

Unfortunately, this is a rush job (always is) and they are on the East Coast (I'm on the West). However, I do have a friend with premiere (but no deck) and he was able to convert the AVIs to MOVs on his PC. When I brought them back onto my Mac, it appears to have fixed the color/luminance issue.

go figure. Just another reason why I hate AVIs.

Andy

I reckon the DV encoding from Premiere must be that different then - I will have to test it on the PAL versions over here in the UK.

The Microsoft DV CODEC is different from the Apple DV CODEC.

There are many DV CODECs each will look different when played on another CODEC (thats if it can play at all)

Some of the main ones are:

Apple DV
Avid DV
Microsoft DV
DVSoft
Canopus DV

They all are different in quality Avid DV being considered the best by many people.

The best bet is to agree on an exact CODEC rather than just "DV" - I would assume that the editor has access to Quicktime and could output you a file in Apple DV rather than a AVI DV file.

Hope everything goes well!

Ben



Post Edited (12-19-05 11:54)



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

I would hope, but the further I get into this project, the more I suspect that the editor didn't really know what they were doing. One could argue that if they DID know what they were doing, they wouldn't be editing on Premiere (lol).

However, from an organizational standpoint and with her lack of ability to provide me with what I need in specific even after I explained what I need, I'm guessing this is her first or second edit for DVD authoring.

Ahh, it would have been better for the client if they had just come to me in the first place. But I've always been put in the situation where I have to clean up someone elses mess.

Thanks for all your help.

Andy

PS: don't get me started on the Avid DV codec. I work with Avids too, but that can be difficult to deal with too in certain situations if the GFX department uses Macs.