Switcher image compression

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haknikor

  • Posts: 1
  • Joined: Wed Nov 02, 2016 4:39 pm
  • Location: Budapest/Hungary

Switcher image compression

PostThu Nov 03, 2016 1:15 am

Hi!
Does anyone know, what kind of image compression is used between ATEM TVS and ATEM Software Control to upload/download stills?

My test is the following:
Image: 1280x720, 24bpp => 1280x720x3 Byte/px + 44 Byte header/footer = 2.764.844 Byte TGA
Fill this image with color #00FF00 (green), and save it as PNG (best compression): 3757 Byte
Upload this file to the ATEM TVS with ATEM Software Control: 24 Byte!!! How?! :)
This is the content of the one and only FTDa packet (thx to wireshark):
Code: Select all
fe fe fe fe fe fe fe fe 00 00 00 00 00 07 08 00 3a c2 ba b2 3a c1 ca b2

Maybe the flif format can be such small like this, but this is not in flif format.
What is this format and how can I encode/decode this?
I would appreciate any tip/suggestion/idea...
Thanks in advance!
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Eddy Briere

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  • Joined: Sat Oct 28, 2017 10:06 pm
  • Location: Paris

Re: Switcher image compression

PostSat May 12, 2018 9:54 pm

Hi,

I'm working on this same point. Have you got more information ?

best regards


Eddy
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Eddy Briere

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  • Joined: Sat Oct 28, 2017 10:06 pm
  • Location: Paris

Re: Switcher image compression

PostThu May 17, 2018 8:05 am

hello everybody,

I am going to post on this post my researchs about the tranfers of images towards a Switch ATEM here.

I analysed data between AYEM Software Control of BlackMagic and a ATEM Studio Tv HD with WireShark.

I written this memo :

eddy-briere.com/tmp/Protocol%20extention%20info%20ATEM.pdf

I saved data from WireShark.

I got data from all tags of cmd FTDa to build a binary file :

eddy-briere.com/tmp/RAW%20IMAGE%20ATEM.bin

Image in png format I transfered :

eddy-briere.com/tmp/test3.png

Today impossible to get RGBA data from this file. Compressed/Image format ??? I tried zip/gzip no success.
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uli peters

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  • Joined: Mon Aug 27, 2012 12:44 pm

Re: Switcher image compression

PostFri May 25, 2018 7:59 am

I guess it's native "10bit UYUVA" (v210 + alpha) format in active picture resolution and color range. You have to convert it first before upload or download and save as well known image file format.
Of course you also have to process the alpha channel correctly (premultiply/unmultiply). The last is what BMD fails to do on their own when reading and writing PNG which have a straight alpha channel but they always assume it is premuliplied (not allowed/possible in PNG!)
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Eddy Briere

  • Posts: 4
  • Joined: Sat Oct 28, 2017 10:06 pm
  • Location: Paris

Re: Switcher image compression

PostFri May 25, 2018 8:35 pm

Hi,

I thought of this type of format at one time. Thank you for your help. Have a nice week end

Ed
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Peter Schuster

  • Posts: 9
  • Joined: Fri Mar 08, 2013 8:43 pm

Re: Switcher image compression

PostSat May 26, 2018 12:10 pm

It might be some kind of run length encoding. I gave up on it, but recently Julusian seems to have figured it out: https://github.com/LibAtem/LibAtem/blob/master/LibAtem/Util/Media/FrameEncodingUtil.cs

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