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shshankjain / webm

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Alpha channel #135

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
Does webm and vp80 include alpha channel (opacity) support (per-pixel). And if 
not, is it planned, and when will it be implemented?
Thank you for answering in advance!

Original issue reported on code.google.com by tombom...@gmail.com on 9 Jul 2010 at 4:45

GoogleCodeExporter commented 9 years ago 
No. It only deals with YUV data. You could fairly easily produce a modified 
version that en/decoded YUVA data, but it wouldn't be compatible with webm.

I doubt official support is planned - VP8 doesn't even support 4:4:4 YUV yet.

Original comment by tdh...@gmail.com on 9 Jul 2010 at 5:02

GoogleCodeExporter commented 9 years ago 
here is a group discussion about this:
https://groups.google.com/a/webmproject.org/group/webm-discuss/browse_thread/thr
ead/8ed99b4738e1a5da

the devs should really think about it, it allows really versatile use (e.g. to 
replace the slightly animated flash banners on top of some webpages or animated 
gifs)

Original comment by trueflyi...@gmail.com on 19 Nov 2010 at 12:12

GoogleCodeExporter commented 9 years ago

Original comment by iss...@webmproject.org on 16 Mar 2011 at 2:51

GoogleCodeExporter commented 9 years ago

Original comment by paulwilk...@google.com on 16 Mar 2011 at 3:59

GoogleCodeExporter commented 9 years ago 
What's the rationale for the de-prioritization? This capability will allow WebM 
to handle entirely new and different use-cases, some that not even H.264 is 
useful for today.

Original comment by slightly...@google.com on 16 Mar 2011 at 9:22

GoogleCodeExporter commented 9 years ago 
Sorry I meant to put this to high.

Original comment by fgalli...@google.com on 16 Mar 2011 at 9:40

GoogleCodeExporter commented 9 years ago

Original comment by fgalli...@google.com on 16 Mar 2011 at 9:41

GoogleCodeExporter commented 9 years ago 
to cite from the discussion:

> Doing it in the codec itself would require changes to the VP8
> bitstream, so yes, the most practical avenue would be to do it in
> additional streams in the WebM container. Not very difficult, we
> just need to bring together the smart people here to spec it out
> and agree on the details.

Original comment by trueflyi...@gmail.com on 2 Nov 2011 at 6:33

GoogleCodeExporter commented 9 years ago 
I couldn't agree more. thank you for participating

Original comment by tombom...@gmail.com on 4 Nov 2011 at 8:44

GoogleCodeExporter commented 9 years ago

Original comment by albe...@google.com on 2 Feb 2012 at 6:52

GoogleCodeExporter commented 9 years ago

Original comment by iss...@webmproject.org on 2 Feb 2012 at 7:00

GoogleCodeExporter commented 9 years ago

Original comment by fgalli...@google.com on 2 Feb 2012 at 8:22

GoogleCodeExporter commented 9 years ago

Original comment by albe...@google.com on 7 Mar 2012 at 11:32

GoogleCodeExporter commented 9 years ago

Original comment by albe...@google.com on 8 Mar 2012 at 12:03

GoogleCodeExporter commented 9 years ago

Original comment by albe...@google.com on 15 Mar 2012 at 6:04

GoogleCodeExporter commented 9 years ago 
[deleted comment]
GoogleCodeExporter commented 9 years ago 
So? Does alpha channel works now ?
This command is supposed to work :
ffmpeg -i my_alpha_video.mov -acodec libvorbis
-vcodec libvpx -pix_fmt rgb32 -ac 2
-ab 128k -ar 44100 -s 480x360 ..\webm_with_alpha.webm

Original comment by joffrey....@yahoo.com on 20 Mar 2012 at 11:27

GoogleCodeExporter commented 9 years ago

Original comment by jimbankoski@google.com on 24 May 2012 at 6:19

GoogleCodeExporter commented 9 years ago 
alpha_encoder added to webm-tools project

http://goo.gl/bRbx1w

Original comment by louquil...@google.com on 15 Aug 2013 at 10:59

GoogleCodeExporter commented 9 years ago 
Amazing! Thanks so much for this fix!

Original comment by misteran...@gmail.com on 16 Aug 2013 at 4:57

GoogleCodeExporter commented 9 years ago 
is there a sample for the decode side of things?

Original comment by hendrikp...@gmail.com on 16 Aug 2013 at 7:31

GoogleCodeExporter commented 9 years ago 
Sample output and green-screen source attached. Chroma-keying in this case was 
done with OpenShot 1.4.3, though Blender is also an option. General guidelines 
here: http://updates.html5rocks.com/2013/07/Alpha-transparency-in-Chrome-video

Original comment by louquil...@google.com on 19 Aug 2013 at 9:14

Attachments:

GoogleCodeExporter commented 9 years ago 
Thanks for the link,

Sorry for not being clearer I meant the vpxdec sample + nestegg.
How to achieve alpha support through the vpxdec sample? Will the sample
decoder be extended?

Thanks

Original comment by hendrikp...@gmail.com on 20 Aug 2013 at 11:13

GoogleCodeExporter commented 9 years ago 
No estimate re vpxdec/samples; very low priority. Patches are always welcome. 
Feel free to open a new issue for it.

Original comment by louquil...@google.com on 21 Aug 2013 at 12:01

GoogleCodeExporter commented 9 years ago 
Since VP8 alpha support is actually not a codec feature but using solely the 
splitter I opened an issue at the libnestegg project which is currently in use 
by the vpxdec.c sample:

https://github.com/kinetiknz/nestegg/issues/12

I'd be happy getting more insights.

Thanks

Original comment by hendrikp...@gmail.com on 29 Aug 2013 at 10:54