How can I export as an FLV file?

[Kevin Lewis]

I am currently running a trial version of Vegas 10. I have been asked to export a video as an FLV file with an alpha channel. The original video was shot on green screen. The final video will be used on a website. Can Vegas create this type of file?

[Seth Bloombaum]

No. Very few encoders can.

What you need is a flash encoder with the VP6 codec, and implements transparency. To my understanding, and I really try to track this one, it's the only way.

Some info about greenscreen in Vegas:
http://www.dvinfo.net/forum/what-hap...en-screen.html

Some info about VP6 encoders:
http://www.dvinfo.net/forum/what-hap...utput-flv.html

In my experience, preserving transparency all the way through internet delivery is a very complex workflow. I include it in a college streaming course, but, it's a capstone project after students have had a full term of conventional streaming projects.

[Kevin Lewis]

Thanks Seth. we had talked about this before in another thread but it now makes more sense now that I have downloaded the trial version. From what i've gathered, it seems that adobe cs5 has this feature. Do you know if this is the case?

[Leslie Wand]

forgive my asking, but why flv?

surely the most logical way (incl. qualitywise) would be to produce a mixed final product?

[Magnus Helander]

I've done this with Sorenson Squeeze.

1. Key the green-screen material in Vegas using the Sony Chromakeyer plug-in (not so good) or BorisFX (better, $299 )
Chroma Key: Plugin for After Effects, Premiere Pro, Final Cut Pro, Final Cut Express and Motion

If you want to use Vegas keyer there's an excellent tutoral from DSE / VASST at
http://www.sundancemediagroup.com/ar...vie_studio.htm

2. Render uncompressed 32-bit AVI from Vegas.
Double check that "Render Alpha Channel" is selected in export dialog.

3. Import huge AVI-file into Sorenson Squeeze

4. Apply a Flash VP6 export preset in Squeeze and activate Alpha Channel in that preset.

5. Apply crop-filter in squeeze so you export smallest possible frame

6. Render FLV with alpha channel from Squeeze

7. test in flash application against intended background

8. Repeat process until perfect or mind lost

Very much trial-and-error, I have not found a desktop media player which will play FLV with Alpha, maybe your flash-coders can provide you with a player in Adobe Air or similar.

...as Seth wrote 'a very complex workflow' which is not an understatement.

Good luck!
/m

[Seth Bloombaum]

Originally Posted by Kevin Lewis

...From what i've gathered, it seems that adobe cs5 has this feature. Do you know if this is the case?

Yes - depending on the CS5 bundle you get, you'll probably have Adobe Media Encoder, and may have Flash (the authoring application). See below...

Originally Posted by Magnus Helander

I've done this with Sorenson Squeeze...
...
6. Render FLV with alpha channel from Squeeze

7. test in flash application against intended background

8. Repeat process until perfect or mind lost

Very much trial-and-error, I have not found a desktop media player which will play FLV with Alpha...

In step #6 in Magnus' summary (which is a good overview), you can use Adobe Media Encoder in place of Squeeze. Both are fine, Squeeze does many other sorts of encodes and has an awesome batch function, but AME comes with many versions of CS5.

However, step #7... if you have to provide the flash app, there are several tasks to develop it. That's where Flash (the authoring application) would come in. In the workflow I've used, import the flv, export as a control-less swf (flv is encapsulated in the swf). Flash will also generate the html embed code. Ah, that's another complication (sorry), the control-less player must be floated in a div layer styled "absolute position" in the html layout.

Perhaps there is a configuration of Flowplayer or JWPlayer that allows one to skip the development of the flash player?

And Magnus very correctly points out that without a media player that supports FLV with Transparency, you have to get all the way to previewing your html layout before discovering any errors that occurred earlier in the workflow.

Once you do have a reliable workflow, you can repeat it many times, so it may be worth the investment in software and testing out the workflow.

[Seth Bloombaum]

Originally Posted by Leslie Wand

forgive my asking, but why flv?

surely the most logical way (incl. qualitywise) would be to produce a mixed final product?

Depends on the user experience you want to create. Using this technique allows you to display a video that shows the background of the web page behind it before, during, and after the clip. It's most often done to get a spokesperson or narrator composited over html content.

Quality can be quite good. Since so many pixels are transparent, almost all the available bitrate can be dedicated to the spokesperson's image; almost none are needed for the background.

[Leslie Wand]

thanks seth, makes sense....