• VEGAS Pro

  How to Render the Alpha Channel in Vegas with a VFW Codec

  Posted by Wayne Waag on January 19, 2019 at 3:56 am

  Ever want to render the alpha channel using a Video for Windows codec such as UtVideo or MagicYUV? If so, you know that only Uncompressed RGB is supported which produces extremely large file sizes. Here’s a relatively old thread that offers a solution, but not for the latest versions of Vegas. https://www.vegascreativesoftware.info/us/forum/why-alpha-channel-on-uncompressed-only–83354/ In a nutshell, enabling the use of other VFW codecs requires a very small change to the aviplug.dll — just change the hex values 75 0A to 90 90.

  Here’s a short tutorial on exactly how to do this using the hex editor HxD. https://mh-nexus.de/en/hxd/ To find the offset address where the hex values are located, I found that the easiest way was to do a search (Ctrl-F) with the tab Hex-values selected and the following string 33 74 07 3D 4D 31 30 34 75 0A C7 86 D8 00 00 00 as the values to be searched. The string is a bit of overkill, but if you search for only the values 75 0A, you will get over a hundred hits. With this string, you will find only the correct one. Here is a screen shot.

  

  Enter OK and the selected values will be highlighted. Then change the values 750A to 9090 (courtesy of Malowz). The edited values will turn red. Enter save and you’re done.

  Here are the address offsets for the following Vegas versions and specific builds:

  v12 build 770 3AD72
  v13 build 453 39FB8
  v14 build 270 39FE8
  v15 build 384 3A378
  v16 build 352 3CCF1

  A couple of tips. Make sure you backup the original aviplug.dll. Copy the plugin to another directory (not in C) before making changes. Once changes are made, then copy back to the correct Vegas directory–e.g. “C:\Program Files\VEGAS\VEGAS Pro 16.0\FileIO Plug-Ins\aviplug” in Vegas 16.

  Once you start Vegas you can verify its working OK by first selecting a render template and then open the Customize Template dialog. You will see that Render Alpha channel is no longer grayed out.

  

  I have tested alpha support for Canopus HQ, Canopus HQX, Magic YUV-RGBA, and UtVideo RGBA VCM. All worked without issue in versions 12-16.

  One final thing. Don’t forget to change the rendered file properties Alpha Channel from None to Premultiplied or Straight (Unmatted).

  

  And now a plug. If you use the RenderEvents tool in Happy Otter Scripts https://tools4vegas.com/, there is an option, thanks to Grazie, to automatically set the alpha channel property–a time saver if you have lots of events to render.

  wwaag

  Wayne Waag replied 7 years, 4 months ago 1 Member · 0 Replies
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