Why Alpha Channel on Uncompressed only?

malowz wrote on 3/14/2011, 6:44 PM
i noticed today that AVI exporter enable the "render alpha channel" check-box for cineform also, besides uncompressed.

but there's a lot of others codecs that support alpha channel, but can't be used to export from vegas.

Canopus HQ and UT Video codec for example.

i use a lot to export from programs like Boris Red, that alow "send" alpha channel to all codecs. but vegas have this weird limitation.

any thoughts on that?


musicvid10 wrote on 3/14/2011, 6:50 PM
Have you tried alpha with DNxHD? The option is there, but I haven't had the need to try it.
I believe Helix I420 also supports alpha.
malowz wrote on 3/14/2011, 7:26 PM
DNxHD if i recall is a QT codec, not VFW.

and i'm not talking about the codec support for alpha, but vegas EXPORT options to allow render with alpha.
musicvid10 wrote on 3/14/2011, 8:03 PM
Limiting it to AVI, as you have done, Matrox Uncompressed + Alpha also renders the fourth layer.

Checking DNxHD, it works as well, and in only 15% the file size of uncompressed.
malowz wrote on 3/14/2011, 10:21 PM
YES! thank you musicvid, you solved my problem, but in another way...

as you mentioned, some uncompressed matrox codecs, vegas alow alpha channel. so i just modded the aviplug.dll and changed the FourCC from one codec to the one i use... now i can have alpha option on any codec!! ;P


PS: i hate quicktime...

musicvid10 wrote on 3/14/2011, 10:31 PM
Glad you got it sorted, but that was an unintended consequence of my reply.

"PS: i hate quicktime... "
I do too, but I love DNxHD (it was made by Avid, not Apple).
malowz wrote on 3/14/2011, 11:12 PM
i just tested DNxHD and your love is "correct", it's really good and fast.

Canopus HQ are very similar (testing exaggerated differences between original > compressed) and its also faster

encode a 1080i clip with same settings as original:

DNxHD: 35 Seconds
Canopus HQ: 26 Seconds

good that we have options... and with alpha! ;P

EDIT: modded even further, now the option is enabled for all codecs ;)
Rory Cooper wrote on 3/15/2011, 3:35 AM
I noticed that you are exporting alpha channel and your clip is interlaced surly that has got to create problems with this type of thing. I am not sure what you are rendering but I would work in progressive with alpha channel content and only on my final output render interlaced but not in the interim.
malowz wrote on 3/15/2011, 9:13 AM
i always use alpha with interlaced content. for years. never had any problem. alpha always perfect.

also, its nice that vegas can do "direct stream copy" (no render) on such files. (it correct identifies 24bits and 32bits files)

EDIT: i did a few tests, exporting from boris red a few primitives shapes in motion, with and without shadow, with and without a solid color background (interlaced with straight alpha).

then, added the same color background in vegas, with the files with alpha. results are IDENTICAL in every case.
Former user wrote on 3/15/2011, 10:45 AM
Alpha channels work fine with interlaced footage.

Dave T2
robwood wrote on 3/15/2011, 5:28 PM
PNG offers lossless compression with alpha; available in image-sequence and QuickTime.
malowz wrote on 3/15/2011, 7:07 PM
PNG compression is also available as a free VFW codec, with alpha too ;)

malowz wrote on 8/17/2012, 7:10 PM
update: to enable alpha channel option to all VFW codecs in Vegas v11, 64-bit, b683.

aviplug.dll file, offset 3AA52 and 3AA53 (bytes "75 0A" ) change to "90 90" to enable alpha channel option to all VFW codecs

works great with Canopus HQ, exporting and importing with Alpha Channel.
Grazie wrote on 8/18/2012, 12:30 AM
This sounds really dangerous??

Should I attempt it?


malowz wrote on 8/18/2012, 2:44 AM
well, doing correctly its not "dangerous" at all.

but anyone can cause a house fire from putting metal on a microwave ;P

you should decide. the consequences will be yours, not mine ;)

but i don't see how someone could cause any damage whatsoever.

create a backup of the file, use a HEX editor, find the offset, verify if the bytes are the ones posted, change, save. done.

in case of any problems, just restore the backup.

Grazie wrote on 8/18/2012, 3:45 AM
What's an HEX editor? And where's the file?


RZ wrote on 8/18/2012, 11:49 AM
Greetings, I would like to incorporate avid codec in my workflow. Could anyone who uses it on a regular basis indicate what the latest version available is. I found one that is 2.3.7 from 2011. Thanks

malowz wrote on 8/18/2012, 1:41 PM
HEX editor is a binary file-editor, much like notepad is a text file editor.

just google it and you can find a bunch of free ones. the offset on the file is the "address" where the modification should be made. all hex editor have the "jump to offset" function to take you to the correct place to change.

the file is:
C:\Program Files\Sony\Vegas Pro 11.0\FileIO Plug-Ins\aviplug\aviplug.dll
LoTN wrote on 8/21/2012, 2:43 PM
Ahahaha, this diverts me so much ...

Thank you for the offset, I too have to replace some relative jumps with a bunch of NOPs.

Now I just have to fiddle around with v10 & v9 libs :))
ritsmer wrote on 10/6/2013, 9:23 AM
Has anyone found the address to enable alpha channel rendering for all codecs in Vegas 12 726 - or at least for Lagarith ??
rs170a wrote on 10/6/2013, 9:30 AM
Greetings, I would like to incorporate avid codec in my workflow. Could anyone who uses it on a regular basis indicate what the latest version available is. I found one that is 2.3.7 from 2011. Thanks

Avid Codec LE 2.3.9

malowz wrote on 10/6/2013, 1:45 PM

I'm downloading update, will test and post address soon.

edit: done.

address: 3AD72
change 750A with 9090


nice companion with script to set alpha to premultiplied on selected clips ;)

//ChangeAlphaChannel.js by Roger Magnusson (roger_74 at home dot se)
import Sony.Vegas;

var ChangeAlphaTo : VideoAlphaType = VideoAlphaType.Premultiplied; //Set this to the type you want

for (var currentTrack : Track in Vegas.Project.Tracks)
if (currentTrack.IsVideo() == true)
for (var currentEvent : VideoEvent in currentTrack.Events)
if (currentEvent.Selected == true)
VideoStream(new Media(currentEvent.ActiveTake.MediaPath).Streams.GetItemByMediaType(currentEvent.MediaType, currentEvent.ActiveTake.StreamIndex)).AlphaChannel = ChangeAlphaTo;
ritsmer wrote on 10/6/2013, 4:16 PM
@ malowz:

Just edited my aviplug as you described - and it works perfectly.

Thank you for answering so quickly.

PS: I wish that SCS would change that "Render alpha channel (uncompressed video formats only)" to work generally - I mean they do not need to check the selected codec (probably also not always possible) but simply make the check box unrestricted.
No big trouble if the selected codec does not handle the alpha channel - they could just change the text "(uncompressed video formats only)" to "(may not work with all codecs)" or the like :- ))

It would be a really great improvement to Vegas.
malowz wrote on 10/6/2013, 7:40 PM
i would like too if they enabled to all codecs, or at least include codecs "on the market" today in the "allow" list.

but i guess they choose the "safer" way, allowing only a few codecs to use it. a simple message box warning is enough to warn users.
Jedman wrote on 10/6/2013, 10:09 PM
Could one of the great people on here maybe upload a modded for alpha channel aviplug.dll, so us simple people could just swap it over?
Would be much appreciated.