How to Preserve Alpha Converting AVI to FLV

FrankLP wrote on 10/9/2013, 8:57 AM

Hi all,
I need some help. I am trying to render out a chromakeyed video (rendering avi uncompressed 32bit) that I need to convert to FLV to work in an Articulate Storyline e-Learning project.

The problem I'm having is that when I render out from Vegas Pro 12 and then convert the avi to flv (using Adobe Media Encoder CS6), the alpha channel doesn't seem to be preserved.

Any ideas on what the right workflow is? Any help is much appreciated.

Thanks.

Comments

natedawg wrote on 10/9/2013, 9:18 AM

You should render out an image sequence in tiff or png.

FrankLP wrote on 10/9/2013, 9:24 AM

When i render out as image sequence, I am left with several hundred png files...which is fine. But I couldn't figure out how to convert all those to a single FLV file. What am I missing?

natedawg wrote on 10/9/2013, 9:35 AM

If I'm not mistaken, you should be able to import the image sequence into media encoder and output from there.

this might help you:
http://helpx.adobe.com/media-encoder/using/add-items-encoding-queue.html

FrankLP wrote on 10/9/2013, 9:59 AM

Thanks Nate...we're making progress. I am able to get the png image sequence into Adobe Media Encoder. And I checked a few of the individual png files to assure that the transparency was preserved from Vegas...which it was.

Now the only problem is that the encoded FLV file doesn't have the transparency preserved. I didn't see any settings in the encoder for this. Any ideas?

larry-peter wrote on 10/9/2013, 10:07 AM

Make sure you're using the On2VP6 codec, and in the video tab check "Encode alpha channel." I don't think the Main Concept codec in Media Encoder gives that option.

FrankLP wrote on 10/9/2013, 10:26 AM

atom,
Is the codec you're referring to for rendering out of Vegas or the Encoder? Also, I don't see a video tab in either Vegas or the Encoder. Can you give me a bit more detail there?

larry-peter wrote on 10/9/2013, 10:37 AM

HI Frank. I'm referring to Adobe Media Encoder. On2VP6 and Main Concept h.264 are the Flash-ready codecs in Media Encoder. I'm not a Flash pro, but have generated transparency in the past. If you select an Adobe Media Encoder template with a .flv suffix, it should be using the On2VP6 codec. An .f4v suffix will use the Main Concept.

Click on the preset you've chosen to open it up for customization. In CS6, it will be in the job queue in the left pane. Then you should see tabs for Filters, Format, Video, Audio, FTP. Open the video tab and the first check box, right under the codec name (which should say On2VP6) is labeled "Encode alpha channel." See if that does it for you.

FrankLP wrote on 10/9/2013, 10:50 AM

Hi atom,
Still not seeing that...here is a link to a screenshot of my Encoder Screen:

http://i29.photobucket.com/albums/c281/FrankLP/Encoder_zps5d713b90.png

FrankLP wrote on 10/9/2013, 10:56 AM

Okay atom I may have stumbled onto it! I right clicked my FLV in the encoder and got the Export Settings SCReen!! Here's what I found:

http://i29.photobucket.com/albums/c281/FrankLP/exportsettings_zps382be30e.png

larry-peter wrote on 10/9/2013, 11:13 AM

Perhaps I should have specified "double-click" the preset in the left pane. I didn't know right click would do also. But that should be what you need. If the render from Vegas preserved alpha correctly I think you're on your way.

FrankLP wrote on 10/9/2013, 11:38 AM

SUCCESS!!!! Thanks guys!!!!!