A

Anonymous

Question

Alpha channel not working with NDI

Forum|Forum|5 years ago
June 20, 2020
3 replies
7421 views

Hi,

I'm trying to use clients Adobe After Effects 2020 for graphics and lower thirds via NDI, 4.5 version, to send to Wirecast or OBS with transparency. When the composition is being played live from AE or played rendered, alpha channel is not being transmitted neither to Wirecast nor OBS or NDI monitor. We get black background in Wirecast or OBS. However, if I export the same composition RGB+ alpha channel as a separate file and then import it into Wirecast or OBS, everything is fine. Full transparency. I tried this same scenario with clients Premier and ProPresenter, alpha channel plays fine live with those, but not AE.

Was anyone here successful with this scenario? Mac OS Catalina, MacBook, Mac Mini and Mac Pro. Someone posted it on Vimeo with this setup and was successful. However, it was PC. What am I missing? I heard some people saying its somethign to do with the PRM not passing the alpha channel during live play. Is this AE problem or NDI's. Hopefully there's an update soon that addresses this.

We have a project that needs lower 3rd changes on the fly and show's dynamics don't allow for exports.

Thanks!

Error or problem

This topic has been closed for replies.

J

Jorge Ocampo

Participant

Found a fix, go to your composition setting and change the background colour to chroma key green : #00b140

R

Rick Gerard

Community Expert

If you are rendering with an alpha channel and the render works when you bring it back into AE or Premiere Pro, then the NDI processing tools do not support alpha channels. Check their specifications.

M

michael ellis

Participant

The NDI protocol lets you send the program panel video from Premiere or AE in real-time to a broadcasting interface to overlay graphics on top of a separate video feed. It 100% supports alpha channels. If you have a lower-third animated graphic in your timeline, you can play it in Premiere/AE and it shows in your broadcast app. But the playback is soft and slightly pixelated.

However, when the sequence is preview rendered inside the app for best playback, the alpha channel goes black. As soon as a change is made to the sequence that disrupts the in-to-out render, the alpha channel goes back to working.

The yellow bar(s) indicates frames for which Adobe Premiere Pro does not have a rendered preview file, and that Adobe Premiere Pro will render right before the playhead reaches them. Adobe Premiere Pro may or may not play back these frames in real time at full quality.

(Alpha channel is transparent when sequence is this color, but playback resolution is sub-optimal)

The green bar(s) indicates frames that have a rendered preview file associated with them and that Adobe Premiere Pro should have no problem playing back in real time at full quality. (Alpha channel goes black when sequence is this color)

H

Henoch0D44

Inspiring

Hi Michael,

Thanks a lot for your explanation.

Hi bplanm,

I think the workaround is to use Green Solid as background and use Chroma Key from Production Software, is that suits your environment?

Newtek NDI Adobe plugin tutorial for live video production. Premiere and After Effects for Titling

I think vMix also said AE doesn't support Alpha Channel and need to use green screen.

M

michael ellis

Participant

I am experienceing the same issue with Premiere Pro 2020.

Before rendering in the timeline the alpha channel works fine, but if you render in to out to get best visual result while playing, the alpha channel is black.

H

Henoch0D44

Inspiring

I also experiencing this issue on Premiere Pro CC 2020 v14.0.0 (Build 38), just like Michael describe. Who should fix this? Is it Adobe or Newtek NDI?

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