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Things That Are Ticking Me Off Today

January 24, 2010, 11:38 am

Overscan.  Yes, I just lost a day of my time to overscan.  Traditional TV sets do not show the entire image they receive from broadcast or DVDs.  They cut off 8-15% of the image around the edges.  This is to make sure there is not black or other border around the image, much like one does in a printing process.  This is fine for an Avatar DVD where one might lose a few leaves in the jungle at the edge, but when I am projecting charts in one of my climate videos, it tends to cut off axes  (when one is working with only 480 vertical pixels (traditional DVD resolutions) it is hard to get detailed charts to project well anyway, but losing resolution to overscan is a further pain.  Making the situation more complicated, DVD's played on a computer or on some (but not all) modern flat screens do have have overscan.

Anyway, I am mostly done, and will post my latest effort here soon.

Tags: ,
Category: Technology
  • http://evilredscandi.blogspot.com Evil Red Scandi

    Does anyone actually use analog television anymore? I'm already halfway through my second HDTV... I don't think I've watched any analog programming in at least 7 years...

  • IgotBupkis

    ERS: Yeah, there are people still using analog sets -- often as a secondary option if not the primary. Also often older people on a fixed income (with their vision, who needs clarity?), but those old TV sets can LAST, and not everyone focuses on TVs in their life so much that they're willing to pay a price premium for a new TV (even cheap flat-panel sets cost upwards from $500, compared to $300 for the older tube-style TVs -- though that's for a larger picture, of course) -- My aunt has a condo she rents out as a sort of time-share, which has a TV in it that is from the early-mid 70s. It works well enough. And the TV she uses was a top-of-the-line 35" set from around 1992. They are likely to get a flat-screen within another 2-3 years, but they're in no rush. They just don't watch TV all that much, mostly the news.

    As to why our favorite BLOGGER here is doing this is another question... ;-D

    Overscan is an artifact of the analog transmission standard, which was designed as-is for a perfectly valid reason, back in the late 30s early 40s... If you're using analog inputs, it often necessarily has overscan for backwards compatibility reasons.

    If you're using modern digital inputs (and you should, if you have them available on both source and monitor) then you won't have this problem

    P.S. -- I assume you meant this (correction in bold):
    DVDs played on a computer or on some (but not all) modern flat screens do not have overscan.

    Most don't actually, and, again -- the primary difference is the inputs being used...

  • Sol

    We don't have a digital TV yet. Indeed, when our local Comcast decided they were switching everything but the very basic channels over to digital, we downgraded our cable package to the very basic channels. I dunno, spending $1000+ to give myself more reason to waste time watching TV just seems like a bad plan.

  • epobirs

    http://www.homevideo101.com/ntsc-safe-zone/

    Most software understands the 'safe zone' for things like text on an NTSC output. You just need to engage it so your image is properly scaled.

    I expect you need to show your video to a lot of your employees, who you've indicated tend to be seniors and likely to have an older display. For those comfortable with computer usage, you may want to include a PowerPoint version using the free viewer app, to enable to charts to be better read.

    ERS: Tens of millions of analog sets are still in use. Otherwise, we wouldn't have had the foofaraw about the decoder boxes in recent years.

    OTOH, you can get a pretty nice display for an ever lower price. That $500 entry level won't last very long, depending on one's requirements. I'm disinclined to buy anything less than 1080p because I need it to double as a computer monitor but for pure TV viewing 720p is fine for a lot of people and delivers a lower price or bigger screen for the same cost as the higher res model.