Alpha channel in video

neuroliquid · 01-15-2016 03:40 PM

I am trying to display video with transparency effect.

At this moment I have solution of using other video as mask:

Code:

IMAGE_TYPE gpu_image_type=film.image().type();

   if(!(gpu_image_type==IMAGE_R8G8B8A8 || gpu_image_type==IMAGE_B8G8R8A8))Exit(S+gpu_image_type);

   Int gpu_image_size=film.image().hwH()*film.image().hwW()*4;

   film.image().lock(LOCK_READ_WRITE);

   film_mask.image().lock(LOCK_READ);

   Byte* data=film.image().data();

   Byte* data_mask=film.image().data();

   for(int c=3; c<gpu_image_size; c+=4)data[c]=data_mask[c-1];

   film.image().unlock().drawFs();

But with full screen video it takes 100% of cpu and framerate drops. Last line seems be the main cause.

Drawing video normally and feeding FadeFx with the mask Images seems to work, so I could use it with lower resolution mask (so extracting image frames would be faster) but the fade effect itself interferes with desired effect.

How can I do it fast?

I also found some information about alpha channel in WebM (http://wiki.webmproject.org/alpha-channel ) but does or will ever Esenthel supports this?

**Esenthel** · 01-16-2016 11:50 AM

Hi,

The document link you've attached to the alpha channel in webm video does not mention anywhere if that video codec supports it, or is it a planned feature for the future.
I think the easiest thing to do would be to grab esenthel source and make a custom shader that combines two videos, uses one as rgb and another as the alpha channel.

neuroliquid · 01-25-2016 03:48 PM

I've lowered the resolution and It works fast enough at this moment but I am still considering playing with shader.

If it comes to codec - it seems that Chrome supports alpha in WebM:
https://developers.google.com/web/update...rome-video

Thanks for reply

Alpha channel in video
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