[mythtv] Patch to autodetect 4:3 Zoom aspect ratio

Matt S. skd5aner at gmail.com
Fri Feb 29 18:37:06 UTC 2008

On Thu, Feb 28, 2008 at 10:56 PM, Chris Pinkham <cpinkham at bc2va.org> wrote:
> * On Thu Feb 28, 2008 at 10:59:54AM -0700, Justin wrote:
> > What is the edge detection algorithm you are using?  Moving to a more
> > sophisticated algorithm could prevent false detections.
> I haven't looked at his code, but what more is required other than "all lines
> above this are black, the next is not" and vice versa for the bottom bar.
> That's what I did in the commercial flagging code does to detect the letter
> and pillar boxes.  In order to make things faster, the commercial flagger
> doesn't check every pixel, but enough to be accurate.  A screen of thin
> vertical lines might make it past the detection, but that's a fringe case.
> --
> Chris

Chris - good thoughts, but wouldn't this be a problem for LiveTV?
Also, sometimes you want to watch commericals (i.e., superbowl) and
some are filmed in letterbox and some in 4x3.  In both those cases,
wouldn't the autodetection have to be dynamic enough to basically do
real-time analysis? The commerical detection code doesn't do anything
besides find commercials, so it definitely could work for that short
period of time.

Another use case I've found from time to time is that content within a
16x9 program will sometimes deliver 4x3 content randomly.  I think
Extreme Home Makeover does that, along with several documentary type


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