Export a PNG Sequence in Adobe Media Encoder with a transparent background

[CaptnCapsLock]

I'm rendering a rather large video file in After Effects, with effects on top of green screened elements, and it seems like I'm runnning into a lot of bugs with the Primatte Keyer plugin. So, I've been rendering the green screened elements out as PNG seqences through After Effects' render queue.

The problem is that the AE renderer (while faster than AME) is much flakier, and crashes every few hundred frames. I render to PNG sequence, and pick "RGB+Alpha" in the channels dropdown.

Where is this option in Media Encoder?

It looks like I get the option to pick " render Alpha Channel only", and "include Alpha Channel", but in both cases I get a solid black background, and not a transparent one.

I've included 2 shots of what I'm seeing in AME, and 1 shot of what I have in After Effects.  I'm basically pre-rendering a PNG sequence to put back into the larger working file so it's not referencing the actual greenscreened effect and crashing, or glitching the render.

[Rick Gerard · Accepted solution]

• Alpha Only gives you a black and white image that can be used as a Luma Track Matte.
• Rendering with Alpha gives you an RGBA file but the Media Encoder preview will see a black background. Previews will also show a black background unless you are using an app that will show a transparency grid. If you import the rendered image sequence into After Effects, you should have transparency. You should also be getting a color image.

[CaptnCapsLock]

Okay, so it DOES give me a transparent background, but doesn't show me with the checkerboard in the preview.

Does that also apply to the previews and thumbnails in Finder? I would have thought all PNGs get treated the same once they are exported with a transparent background.

[Rick Gerard]

The app you use to look at a file with RGB, and A channels determine whether or not you can see or use the transparency. Most apps and all common media players do not support Alpha Channels.

[CaptnCapsLock]

Okay, got it, Thanks!

I finally cleared off the rest of my render queue and got around to trying this, and yes, I do get a PNG sequence with a transparent background, even though the AME preview doesn't show it. It shows up as transparent in my other apps as well...
... is this a bug?

The checkerboard pattern is the visual language every other Adobe program uses to show a transparent background, but here (when I'm exporting a PNG sequence of black shadows) it shows that transparent background as solid black.

[Rick Gerard]

It is not a bug. The media encoder preview does not have a transparency grid. Most apps that will preview images do not.