Importing AVI’s with alpha channel PAL

[Grinner Hester]

try smacking it and yelling dude.

[Erik Pontius]

You don’t specify what problem you are experiencing.
Here’s a few common problems and solutions:
Your AVI will either have to be uncompressed or in a codec that supports an alpha channel…DV will not.
Make sure that you actually exported your footage with an alpha channel. Applications like After Effects you will need to specify that you want to export the alpha (usually by choosing “Millions of Colors +”).
Also, Avid seem to like “Straight” alphas more than “pre-multiplied” alphas.
Also, Avid sees alpha channels as they would be in film…white areas being transparent, black areas being opaque. This is the reverse (or inverse) of what most graphics applications like AE and Photoshop use…black being transparent, white being opaque. You’ll need to choose the option to “invert alpha” when importing your footage.
You may also want to try a different format altogether. Exporting your titles using the Quicktime Animation codec specifying to include the alpha (Millions of colors +).

Erik

[Mcqueen]

When I create a project in HDV (PAL) the import of AVI’s and QT’s at a resolution of 1920 x 1080 both with alpha channels works perfectly well but when I try importing importing AVI’s and QT’s at a resolution of 720 x 576 in a DV (PAL) project it looks as if it is going through the motions but just comes up with black. These are AVI’s and QT’s that worked perfectly well in version 4.6. My import settings are set to invert alpha as was the case in 4.6. I havew also installed Premiere to check that the files are ok and they import properly there.

[Erik Pontius]

What happens if you ignore the alpha and just import the video without the alpha? Wonder if Avid is having problems reading the codec properly. Usually, files that are using a codec Avid can’t read show up as white…so inverting that might end up with a solid black frame.
What codec, if any, are you using in your AVI’s and QT’s?

Erik

[Mcqueen]

Not sure which codec (Ulead Cool 3D) files but the files both AVI and QT were OK in Xpress Pro 4.6.
I’ve just noticed that the filler tool doesn’t work now either.
I have downloaded the very latest version 5.7.2 but still the same.

The only other change that I have made is downloaded Windows Media 11 could this be the problem?

[Grinner Hester]

yes. Don’t let your system download drivers and such on ya.

[Erik Pontius]

I would doubt WMP11 would do anything. WM9 is a requirement for Xpress now, WMP11 contains some updated WM9 codecs and player. However, Avid is QT based primarily using WM only as an export option. You’re more likely to have problems with updated QT versions, IMHO.
That’s not to say it couldn’t be related…Avid is EXTREMELY picky about any kind of driver and software updates.
If you have photoshop or After Effects you might try creating something with an alpha and see if you get the same results, it maybe that the 3d app that created your files is creating alphas Avid just can’t understand for some reason.
There is also a handy tool called “Gspot” that can identify what CODEC a file is using (amongst other info).
Otherwise, see if you can re-export the files out of your 3d app using the QT Animation codec or uncompressed AVI.

Erik

[Mcqueen]

Both the AVI’s and QT’s are saved uncompressed with alpha channels. However I have just noticed that in my HDV project I am using the import settings for aspect ratio of 601/709 non square and in my DV project I am using maintain and resize square. I have now changed the DV Import settings to 601/709 non square and hey presto I am up and running.
Still haven’t a clue which aspect ratios I really should be using. I prepare HDV Animated titles at a resolution of 1920 x 1080, Widescreen DV at a res. of 1048 x 576 and standard DV at a res. of 768 x 576 and up until now everything has worked.

Thanks for your help.

[Erik Pontius]

Ah…
I wondered the same thing a while back…the answer was in the help file. You’ll obviously pick non-square 601/709 for graphics/video rendered using aspect ratios like NTSC 720×480 using a PA of .09 but also for their square pixel equivalents like 720×540.

For HDV projects the files you will be importing will be end up ultimately using the Avid DNxHD 145 codec. Which is 1920×1080 square pixles upper field first. You can skip a step, speed up the process and save some space by rendering your graphics and other composites using the Avid DNxHD 145 codec (granted the application supports exporting to a QT file). If you have a separate system for graphics and compositing, you can install the Avid codec pack which you can download from the Avid website. Importing the files you would use the 601/709 non-square pixel import setting.

Erik

[Erik Pontius]

Oh…however, the Avid DNxHD codec doesn’t support exporting with an alpha channel…you’ll still need to use uncompressed AVI or Quicktime animation or other codec that supports one.

Erik