Modulus change from 16 to 2 - question

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Greg Staten
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Joined: Mon Oct 25, 2010 6:10 pm

Modulus change from 16 to 2 - question

Post by Greg Staten » Fri Feb 15, 2013 1:58 am

Noticed about a hundred builds ago the modulus was changed from 16 to 2. Just wondering why the change was made all the way down to 2. I've always understood (from my testing with H.264 decode implementations) that a modulus under 8 was risky for compatibility. Have you all found that this is no longer a decode issue? Certainly 2 makes it easier to deal with arbitrary crops, but I've always made sure the math worked out to 8 when adjusting size and crops.

Thanks!
-greg

mduell
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Re: Modulus change from 16 to 2 - question

Post by mduell » Fri Feb 15, 2013 3:20 am

It's less of an issue than ever. iDevices, mainstream Android, Roku/WDTV/etc all support mod 2.

I didn't think 8 helped compatibility, I thought it was 16 or no improvement.

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Rodeo
HandBrake Team
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Re: Modulus change from 16 to 2 - question

Post by Rodeo » Fri Feb 15, 2013 11:39 am

Some devices have issues when the dimensions don't divide cleanly by 4. Never encountered any, though IIRC TedJ did. In 99.9% of cases though, mod 2 will work fine.

TedJ
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Re: Modulus change from 16 to 2 - question

Post by TedJ » Fri Feb 15, 2013 10:58 pm

I'd seen playback issues with the PS3 with mod2 dimensions, although I haven't checked in about 2 years.

Greg Staten
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Joined: Mon Oct 25, 2010 6:10 pm

Re: Modulus change from 16 to 2 - question

Post by Greg Staten » Tue Feb 19, 2013 10:35 pm

Thanks for the information. Hadn't realized that Mod2 had been so widely adopted.

Thanks!
-greg

jamieburchell
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Joined: Sun Jan 06, 2013 10:43 pm

Re: Modulus change from 16 to 2 - question

Post by jamieburchell » Sun Feb 24, 2013 11:04 pm

I'm wondering how the videos I've previously encoded with Loose/Mod16 are inferior to Mod2? Is it that mod2 can get closer to the intended aspect ratio? Does it really matter/notice? :?:

GregiBoy
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Re: Modulus change from 16 to 2 - question

Post by GregiBoy » Mon Feb 25, 2013 12:54 am

No it really doesn't matter so long as they play on your target devices.

I would suggest that you would not be able to pick any difference.

Give it a go though on a chapter or so of your favourite movie and see if you can pick anything!

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