Topic by Bisqwit

Posted: 7/1/2007 7:07 AM

Post subject: Automatic screenshots

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Bisqwit

Editor, Active player (296)

Joined: 3/8/2004
Posts: 7469
Location: Arzareth

[TODO]: rewrite this message consisting of scattered quotes into a coherent form. Summary: NesVideoAgent has been editing submissions adding a pile of screenshots into them. ---- It uses an algorithm to try to find out interesting shots. It gives each frame a value based on how much action is there and how little monotonous the screen is, and then splits the movie into N pieces and finds the M most interesting pieces, and then picks the most interesting frame from each of those pieces. Action = sprites move. It ignores screen scrolling. It is rather difficult coming up with an aesthetically pleasing algorithm. I got some chuckles when I first saw how the bot took literally what I wrote and completely ignored the meaning behind it. So computerlike. It totally exposed the holes in my algorithm that I didn't think of. Re: cleaning up ROM names-- Hmm, yeah it cleans up them in the process as it verifies which ROM works. Re: purpose-- The purpose, idea behind it is to give an insight of the new movie as someone submits a movie of some never-heard-before game. But there are so few pending submissions so I ran it on a select few old submissions. Screenshots often tell a lot.

Posted: 7/1/2007 8:55 AM
(Edited: 7/1/2007 12:59 PM)

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Randil

Skilled player (1886)

Joined: 4/20/2005
Posts: 2160
Location: Norrköping, Sweden

Sounds interesting. Perhaps it could also be possible for NesVideoAgent to take the contrast between the sprites and the background into account. For example, if there are only blue sprites on a screen with blue background, it might be hard to see what's going on. This is probably too hard to judge for NesVideoAgent though, but it would be nice if it worked.

My own page on this site.

Posted: 7/1/2007 12:49 PM

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Baxter

Skilled player (1402)

Joined: 5/31/2004
Posts: 1821

That's a pretty nice feature. It seems to work pretty well, although for both the regular zelda run, and the outlands run more than 1/3th of the screenshots are at the menu screen.

http://tasvideos.org/Baxter.html

Posted: 7/1/2007 2:53 PM

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Bag_of_Magic_Food

He/Him

Active player (278)

Joined: 5/29/2004
Posts: 5712

It's been said that's because the menu screens tend to have a better variety of colors, which is one thing the algorithm looks for.

put yourself in my rocketpack if that poochie is one outrageous dude

Posted: 7/1/2007 5:19 PM

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AnS

Emulator Coder, Experienced player (723)

Joined: 2/23/2006
Posts: 682

I think these screenshots should be taken judging by input density - additional algorithm searches for areas with unique input patterns and returns calculated priority for each frame - this priority works as additional factor along with result of screen/sprites analysis. Of course input factor shouldn't be used alone, but in couple with action meter it may at least take away unimportant screens (usually input isn't very varying at such places like menu or unavoidable cutscenes).

Posted: 7/1/2007 10:38 PM

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JXQ

Experienced player (750)

Joined: 5/6/2005
Posts: 3132

The SNES implementation of this is...well, something isn't right with it. Example 1 Example 2

<Swordless> Go hug a tree, you vegetarian (I bet you really are one)

Posted: 7/1/2007 10:39 PM

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Bisqwit

Editor, Active player (296)

Joined: 3/8/2004
Posts: 7469
Location: Arzareth

JXQ wrote:

The SNES implementation of this is...well, something isn't right with it.

I'm aware of it. Somehow, loading of savestates causes emulation corruption. Edit: With valgrind, I tracked some errors in the savestate code, trying again now.

Posted: 7/2/2007 11:53 AM

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JXQ

Experienced player (750)

Joined: 5/6/2005
Posts: 3132

On the SMW screenshots, they look like they have background clipping off (default toggle is Backspace), causing some blue backgrounds to turn black.

<Swordless> Go hug a tree, you vegetarian (I bet you really are one)