View Full Version : ? about Alpha Channel
February 10th, 2011, 12:21 PM
I am currently running the trial version of Vegas 10. When I export an AVI with an alpha channel, is there a way to confirm that the alpha channel has in fact been included. I am having trouble with the transparency. I can tell the clip is transparent within vegas because of the checkered background. Outside of vegas, all I get is the black background. Any thoughts?
February 10th, 2011, 12:27 PM
Drop it on a Vegas timeline with something else under it to confirm transparency.
February 10th, 2011, 02:01 PM
AFAIK, Vegas will only render the Alpha channel in uncompressed format. It used to be like that, I don't have Pro v10 though.
February 10th, 2011, 02:18 PM
It's still the same in Pro 10.
I just tried doing what I recommended and it works with uncompressed AVI.
Remember to set the clip alpha channel property to Straight (unmatted) when you do this or you won't see the transparency effect.
February 10th, 2011, 06:14 PM
I used the straight unmatted on the clip along with checking the box when rendering. As a test I tried to export to an uncompressed avi. Once rendered I brought the clip back into Vegas and the I once again had to clicl on the properties of the clip and click straight unmatted. Its like it didnt save. I'm trying to bring the final clip with an Alpha channel into another NLE. ANy additional thouhgts on what I can try?
February 10th, 2011, 07:39 PM
Kevin, apologies for the confusion.
I set the properties to Straight (unmatted) AFTER I rendered it as an uncompressed AVI and brought it back into Vegas, not for the initial render.
I brought it back into Vegas just to confirm that it did keep the alpha channel after rendering.
February 11th, 2011, 09:58 AM
Does that mean that I dont need to click Straight (unmatted) on properties prior to rendering as long as the alpha box is checked? If this is the case I'm assuming that you only need to click Straight (unmatted) on properties if you want to actually see the transparancey within Vegas?
February 11th, 2011, 10:58 AM
Kevin, you're correct on both counts.
February 11th, 2011, 02:24 PM
Ok, looks like I have figured it out. Now on to part two. I have importated the clip with the alpha channel to Sorenson Squeeze 7. I am now having trouble exporting a flv file witht he alpha channel intact.If you are familer with Sorenson 7 and have any advice that would be great. Meanwhile I will post the question in a different part of the fourm.
February 11th, 2011, 02:42 PM
I've never used Sorenson so you'll have to get help elsewhere.
Good luck with it and let us know how it turns out.
February 11th, 2011, 05:04 PM
I'm back on Squeeze 6, but here is a snap of my relevant transparent flv settings.
Note that only Flash 8 / VP6 codec supports transparency. Not Flash 7 / Spark, not Flash 9r3 / h.264, not Flash 10 / .f4v.
Such a file will play in any Flash8 or later player install, but there are also some tricks to making it work on a web page, where I assume you're going. wmode=transparent is probably the most important param to set in the flash player embed.
Where are you having trouble? How did you create your flash player (if you've gotten that far).
February 11th, 2011, 06:53 PM
Seth, thanks for your input, I was hoping that you would chime in. The seeting that i'm using look exzctly like the ones on you snap shot. The one thing that I will double check is the box that says
"Format Constraints". I have someone thats more famalier with webcode helping me so I can really explain how the player is being created. When I play the exported flv on the site, there is a white background behind the video. No transparency. The folks over at Sorenson suggested that I reinstall Sorenson to see if that helps. I am running the trail version which should have no limitations with the exception of a watermark. I will reinstall and see what happens. I will keep you posted.
February 11th, 2011, 07:51 PM
I just checked format constraints and it matches your screen shot. Theres is aboxtitled profile which gice the options of vp6E or vp6s could picling the wrong one cause this problem? Also could the alpha dat rate be thue issue?
February 12th, 2011, 11:24 AM
VP6e is the pro codec for standard def, VP6s was released later for HD - both should support transparency. I've not really benchmarked VP6s, as I haven't done much HD in flv. It would be worth looking at for HD.
Alpha data rate, which I have set at 25%, shouldn't affect the basic transparency, moreso whether it's good or bad transparency. I'd expect the "good" range to be somewhere between 10 and 25%, with 25 as a safe/conservative choice. Think about what Alpha is - it's a 256 level-per-pixel channel, just like the R, G, or B.
Has your web coder ever produced transparency with Flash video? There are so many places in a flash transparency workflow to get it wrong; I wouldn't assume that you're doing something wrong, it is just as likely to be the web coder if they're not experienced with this.
February 12th, 2011, 11:47 AM
The source file is HD would clicking on VPe instead of S cause the problem?
February 12th, 2011, 03:47 PM
No, the choices of VP6e vs. VP6s shouldn't affect transparency.
Kevin wrote me separately, and included this code:
<param name="movie" value="FLVPlayer_Progressive.swf" />
<param name="quality" value="high">
<param name="wmode" value="transparent">
<param name="scale" value="noscale">
<param name="salign" value="lt">
<param name="FlashVars" value="&MM_ComponentVersion=1&skinName=Clear_Skin_1&streamName=FLV/CopyofR1rob&autoPlay=true&autoRewind=false" />
<param name="swfversion" value="8,0,0,0">
The above code is incomplete. Try this:
<object classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=10,0,0,0" width="320" height="240" id="fcpgreen">
<param name="allowScriptAccess" value="sameDomain" />
<param name="allowFullScreen" value="false" />
<param name="movie" value="myfile.swf" />
<param name="loop" value="false" />
<param name="quality" value="high" />
<param name="wmode" value="transparent" />
<param name="bgcolor" value="#ffffff" />
<embed src="myfile.swf" loop="false" quality="high" wmode="transparent" bgcolor="#ffffff" width="320" height="240" name="fcpgreen" align="middle" allowScriptAccess="sameDomain" allowFullScreen="false" type="application/x-shockwave-flash" pluginspage="http://www.adobe.com/go/getflashplayer">
As referenced in some other thread, the embedded player needs to be floated in a div that is styled with absolute position. If your coder can figure things out from the my above sample, that's great. I'm concerned, though, that the sample he/she supplied was so incomplete; suggesting he/she is unfamiliar with flash video in html. The first flash video project one undertakes should not be one involving transparency! More education than I can provide online might be needed. There are whole books written on the subject, and complete classes as well.
February 12th, 2011, 08:17 PM
Seth thanks for your help. The VP6e vs. VP6s was actually the problem. I changed the setting and it now works perefctly. Thanks again for you input.
February 13th, 2011, 06:53 PM
Kevin, that's great you got it working. I'm surprised it came down to VP6s vs. VP6e! What are the pixel dimensions of your final video? I'd like to know a little bit more about your experience, so I can share better info.
February 14th, 2011, 10:07 PM
I'm not sure what pixel dimensions that Sorenson applied, but I can tell you that the source footage was shot in HD with my Canon XHA1 (30P). The file that I imported into vegas was a 1920x1080. The rendered file was a 720x480 that I imported into Sorenson. I am glad that you told me about the VP6 codec. That got me off to a good start.