Posted: 6/20/2010 2:16 PM
Post subject: Automatic screenshots for submissions
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Chef_Stef
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Joined: 5/23/2006
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A few years ago, Bisqwit implemented an automatic screenshot feature for submissions (see threads here and here). The screenshots would be added to the bottom of the submission text and could be removed if desired. Somewhere around late 2008/early 2009, the feature was disabled. Why was this done? Did Bisqwit lack the resources to continue, or was the feature deemed unnecessary? I can't find any threads/posts on the forum discussing (or even acknowledging) the change. Personally, I liked the automatic screenshots because they served as a preview to the movie/game itself. Sure, the selection algorithm wasn't perfect, and sure, these screenshots were almost never actually used as the final movie screenshot (this movie being at least one notable exception), but they still served a nice purpose that I've been missing since they were disabled. Should we consider re-implementing this feature?
Posted: 6/20/2010 2:22 PM
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scrimpeh
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Don't see why not. Then however, it's probably better to have a handpicked screenshot that shows the game better.
Posted: 6/20/2010 3:45 PM
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klmz
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The screenshots could be useful since them did attract me to some movies of obscure games. It could be re-implemented as an optional feature toggled by the submitter.
<klmz> it reminds me of that people used to keep quoting adelikat's IRC statements in the old good days <adelikat> no doubt <adelikat> klmz, they still do
Posted: 6/20/2010 3:52 PM
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Derakon
Joined: 7/2/2007
Posts: 3960
I always liked the hand-picked screenshots. I remember Bisqwit described his algorithm awhile back. It went something like this: * Pick a number of screenshots, N * Start running the game in an emulator. There are F frames in the run. Pick a window size, W. * When the current frame f is within i * F / N +- W, start comparing the current frame's image to the previous frame's image. * Use a correlation coefficient to compare how much two frames have changed. Find the frame within the window that has the greatest change from the previous frame; these are considered to be interesting frames. I don't think this would be particularly complicated to (re-)implement. Only problem is that it tends to work poorly in games like Zelda where the frames of greatest change are those where you're scrolling to the inventory screen or to another room.
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Posted: 6/21/2010 3:40 PM
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Warp
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Joined: 3/10/2004
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Maybe instead of taking a snapshot of frames with the greatest change, take a snapshot from between two frames with greatest changes. If frames with greatest change can be considered "cuts" in film terminology (in games it would happen eg. when changing from one level to another), the snapshot would be taken from the middle of the "scene".
Posted: 6/21/2010 5:08 PM
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Mitjitsu
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I'd prefer if there was some code which allowed the users to pick screenshots without the need to upload the pics themselves such as SCREENSHOT 25234,54221,65421
Posted: 6/24/2010 9:58 AM
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Warp
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Mitjitsu wrote:
I'd prefer if there was some code which allowed the users to pick screenshots
It's not like the two features would be mutually exclusive.
Posted: 7/9/2010 9:51 AM
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Jess
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Joined: 3/31/2010
Posts: 46
I can see two options with this: 1.) Allowing the player to select automatic screenshots 2.) Allow the player to select which frames the screenshots should come from Of course, there would always be the option to manually upload screenshots. I think that about covers it?
Posted: 7/9/2010 5:03 PM
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Derakon
Joined: 7/2/2007
Posts: 3960
I would say, a checkbox that says "Automatically generate screenshots", as well as a text field that accepts a comma-delimited list of frame numbers from which screenshots would be taken. Both could of course be left empty.
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Posted: 7/9/2010 6:10 PM
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sgrunt
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There are at least two major problems I can see with reviving this concept. First, this would need emulation software to be installed on the server, with all of the requisite ... support files; this would take up a large amount of disk space and might not be easy to assemble, not to mention many of the emulators currently in use are Windows-specific (and difficult to capture from in the Linux environment the server uses). Second, the capturing process would require the emulator to be run, slowing things down on the server even more than they usually are. Our encoders and publishers are already fairly reliable at screenshot capturing, and I don't think the prospect of a handful automated screenshots is worth the above sacrifices.
Posted: 7/14/2010 9:12 AM
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Warp
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sgrunt wrote:
First, this would need emulation software to be installed on the server, with all of the requisite ... support files; this would take up a large amount of disk space and might not be easy to assemble, not to mention many of the emulators currently in use are Windows-specific (and difficult to capture from in the Linux environment the server uses).
Unless I'm mistaken Bisqwit originally had the game roms in a compressed file system (which he developed himself), saving a great deal of disk space while still having the files available as if they were in a regular file system. And many of the emulators are available for linux as well (and in fact, can probably be automatized better there). I'm not arguing pro reinstating the automatic screenshot feature. Just commenting.
Second, the capturing process would require the emulator to be run, slowing things down on the server even more than they usually are.
This problem could be solved by someone with a computer which is running 24/7 donating some computing time for this purpose (iow. the tasvideos server would simply contact that computer and ask it for the screenshots, which it would then get back or, if it doesn't respond, it could then just skip them). Since it's not an essential feature, any downtime of this "slave" secondary server wouldn't be such a huge catastrophe.
Posted: 7/18/2010 2:28 AM
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Bisqwit
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13 months ago I have documented the automatic screenshot process, that I used, including the criteria for picking interesting frames, here: http://tasvideos.org/NesVideoAgent/AutomaticScreenshots.html and here: http://tasvideos.org/Bisqwit/Source/BeautyAnalyzer.html In retrospect, I think a LUA script could be written that works for most emulators. Only analyzing the screen content is a bit slow to write in LUA. Also, Warp is correct re: the ROM storage. All of SMS, NES, Genesis, AGB, DMG, SGB and GBC ROMs, including the myriad of overdumps, hacked and patched versions, in 8907 MiB total. SNES was 1629 MiB. None of the emulators need 7zip/zip/whatever features within them. It's just a filesystem.