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Smallest File Size yet keeping Alpha Channel

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Stephen Curry
Smallest File Size yet keeping Alpha Channel
on Aug 9, 2012 at 9:39:24 pm

Hey guys,

I've got some HD Digital Juice video files in .mov format with Alpha.

Some of these 10sec files are over 1G in size.

Is there a format I can render them out in that will keep the Alpha channel and quality but reduce the size of the file.

Currently I've been reducing the dimensions from 1920x1080 to 1280x720 RGB+Alpha PNG


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John Cuevas
Re: Smallest File Size yet keeping Alpha Channel
on Aug 10, 2012 at 12:28:30 am

I like Avid DNxHD it's not the smallest codec, but really high quality and there are a bunch of different bit rates to try if you want to change the final size. One thing, you have to go into the codec settings and choose "compressed/uncompressed" alpha along with changing the color to RGB + Alpha to create an alpha channel.

I just did a test between a 17 second
QT animation 1080i/29.97 = 2.9 GB, 492 MB for
QT_Avid DNxHD 1080i/59.94 145 8-Bit.

Avid Quicktime Codec

Johnny Cuevas, Editor

"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.

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Stephen Curry
Re: Smallest File Size yet keeping Alpha Channel
on Aug 10, 2012 at 11:12:06 am

Thanks John....I render out using that Codec with 720p/29.97 110 8bit and it was about 20M smaller than what I was doing otherwise....

any little helps :-)

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Tom Masters
Re: Smallest File Size yet keeping Alpha Channel
on Aug 14, 2012 at 8:11:01 am

look into proxy workflow.. it is super simple and a real time (and CPU) saver.

if overall size is your concern.. Photo JPEG is a great format that honors color pretty well.
Unfortunately cannot combine alpha channel.
But if you want to render separate picture and alpha channels, the black/whit alpha pass in PJPEG is very small file size. I use this often on 8-bit workflows.

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