OT: Youtube thumbnails

baysidebas wrote on 3/4/2009, 8:23 AM

Has anyone figured out the algorithms behind Youtube's generation of the three thumbnails available for the uploaded movies? Since there's no other choice given, if there's a repeatable determination it may help in editing the video to locate scenes that will be chosen by Youtube and thus make a meaningful thumbnail available. I know, it's like the tail wagging the dog, but the choices provided by Youtube just aren't acceptable.

Comments

TheHappyFriar wrote on 3/4/2009, 8:36 AM

i don't know how to determine a thumb (one time I had 3 white thumbs!) but if you're linking in a forum/webpage, you can use your own thumb & open in a new tab/window. I've done that.

Tim L wrote on 3/4/2009, 9:53 AM

I believe the 3 thumbnails are taken 25%, 50%, and 75% into your video. The default is the 50% thumbnail.

This is why you sometimes see a video with a seemingly random fraction-of-a-second image in the middle of it -- timed so that it becomes a thumbnail choice.

baysidebas wrote on 3/4/2009, 10:37 AM

Tim, you're right that the default is the middle thumbnail, but the points don't match my results.

To test I uploaded 3 short videos of Sony Time Code out of Vegas with solid color backgrounds [in case there was scene detection going on].

The thumbnails were generated at:



0:21;11     0:39;17     1:31;20      total length, 1:41 scene changes every 10 seconds

0:21;17     1:37;23     2:25;04      total length, 2:30 scene changes every 15 seconds

1:00;24     1:36;20     2:29;25      total length, 3:30 scene changes every 20 seconds

I also uploaded 2 versions of a 3:49 length video, the second with a 10 second black leader. The resultant thumbnails were the identical frames, even though the second set was displaced by the 10 seconds taken by the leader. This was an earlier test that led me to think in the scene detection direction.

xberk wrote on 3/4/2009, 11:47 AM

For someone with time on their hands, found this formula at http://www.squidoo.com/youtubeframe YouTube may be using this for thumbnail choices or NOT.

How To Calculate The Exact Placement
X = Video length (in sec.)

baysidebas wrote on 3/4/2009, 1:52 PM

I took the friar's advice. Used my own thumb and linked to a copy of the webpage with the movie set on autoplay. There's a brief interruption while the new page loads, but i can live with that.

Jim H wrote on 3/4/2009, 5:16 PM

Youtube recently announced that it changed it's thumbnail algorithm to some random scheme. Where once you could rely on the 50% rule, no more...at least that's what they said. In a 2 DEC 08 blog they said:

"Improved thumbnails - To make sure your thumbnail represents your video, your choices will now be selected algorithmically. You'll still have three thumbnails to choose from, but they will no longer be auto-generated from the 25/50/75 points in the video index."

I think they were trying to kill the thumbnail cheats who would put frames of half dressed women in the middle of their vids to attract attention. And it works. I like to think that I was the original thumbnail cheat. As an experiment back in Youtube's early days (December 2005) I posted this video and it quickly became my most viewed (that is until I exploited the Chris Crocker thing and surpassed 1M views):

If you can find a thumbnail cheat earlier than that I'd like to know. Sorry if I messed it up for the rest of you...heh heh...

NickHope wrote on 3/4/2009, 8:04 PM

I can upload a thumbnail for my YouTube videos but this might well just be because I'm a YouTube "partner". Or perhaps because it was previously a "director" account. Maybe they'll give everyone that functionality at some point.