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Discussion Starter · #1 ·
Does any one know of a way to program a background software program to detect the aspect ratio of a DVD?


I would like to us the com port on a HTPC to control servo motors attached to the curtain rods in my theater to adjust when watching different formats on my CH system.


Automation!
 

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There are two ways, both of which, can be almost equally unreliable. One is to read the header of the DVD and see if the aspect ratio field is present. If it is not, pot luck. If it is it may not contain the correct information (Orignal aspect ratio and aspect ratio are often not used correctly in the DVD header). The second is to examine the frames and "look for" the black bars. There may be a third; but, I am unaware of it.
 

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Vern,


Is your Masking system automated at all with your HTPC? Or do you manually press a button for each aspect ratio?
 

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I have a button for each preset.


Since I have multiple sources (TT, PowerDVD Ultra, CII scaler) automation would not be easy to accomplish. What I did was to include a set of buttons for the curtain on each of the programmable remote pages for the various sources (TT, PDVD, CII, FIOS, etc) so opening or closing the curtain or choosing a preset was convenient. I did the same for my basic houselight control.


Vern
 

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Discussion Starter · #6 ·
I use marcos on my remote and IRman and Girder within the PC. However, I would like to set the curtains via the same process. But, there is no way that I know of to automatically detect or pick a particular AR.


My goal is to push the envelope and have a preview running(homemade from HD) on the screen while the dvd loads, sets the parameters and then make adjustments for the main feature.
 

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How accurate is AR flagging on DVDs? I gotta think black bar detection is asking for trouble. On a movie where the aspect ratio 'changes' (say, when displaying 'historical' footage, etc) would that not trip the detection software/hardware or is the movie 'masking' still brighter than the bars?


Personal aside based upon in depth experience gained in other areas: Automation past a certain point is far more work than it's worth. Either you expend much time and effort in preventing/handling errors/exceptions or you spend even more time (and often money) dealing with the aftermath when the automation goes awry... and it always seems to. There's almost always SOME nutty situation you didn't think of that throws a wrench in the works. The subject at hand seems to cross that line IMO... neat idea but difficult to implement properly.
 

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Quote:
Originally Posted by redillow /forum/post/0


Does any one know of a way to program a background software program to detect the aspect ratio of a DVD?


I would like to us the com port on a HTPC to control servo motors attached to the curtain rods in my theater to adjust when watching different formats on my CH system.

Hi,


Im working on a system to do this at the moment. I am using VLC to blend two CRT projectors, and the author of the panoramix plugin that does the blending added the functionallity to output the detected ratio to the stderr output of VLC. Using a Perl program I can launch VLC and capture the stderr output checking for ratio changes. (The output is sent as an integer from 0 -> 2350).

The next stage that I'm working on right now is to modify a curtain opener to add a serial interface so my Perl program can send commands to move to the correct position. This is based on a PICAXE microcontroller.


My first version had several reed switches mounted to the curtain track to set the different aspect ratios. However, in practice this didn't work so well due to the large number of possible ratios. So, I'm redesigning it at the moment with an opto-sensor on the drive wheel to count the revolutions to set the position.


Sorry if this doesnt help you much, but at least you know someone else also has the same idea. I intend to document the system properly if I get it working to my satisfaction!


Cheers,

Ben
 

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Quote:
Hi,


Im working on a system to do this at the moment. I am using VLC to blend two CRT projectors, and the author of the panoramix plugin that does the blending added the functionallity to output the detected ratio to the stderr output of VLC. Using a Perl program I can launch VLC and capture the stderr output checking for ratio changes. (The output is sent as an integer from 0 -> 2350).

The next stage that I'm working on right now is to modify a curtain opener to add a serial interface so my Perl program can send commands to move to the correct position. This is based on a PICAXE microcontroller.


My first version had several reed switches mounted to the curtain track to set the different aspect ratios. However, in practice this didn't work so well due to the large number of possible ratios. So, I'm redesigning it at the moment with an opto-sensor on the drive wheel to count the revolutions to set the position.


Sorry if this doesnt help you much, but at least you know someone else also has the same idea. I intend to document the system properly if I get it working to my satisfaction!


Cheers,

Ben

Sounds very interesting. Please keep everyone updated.
 

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Quote:
Originally Posted by kanebear /forum/post/0


How accurate is AR flagging on DVDs? I gotta think black bar detection is asking for trouble. On a movie where the aspect ratio 'changes' (say, when displaying 'historical' footage, etc) would that not trip the detection software/hardware or is the movie 'masking' still brighter than the bars?

VLC uses the black bar detection method, and yes you're right this sort of material does cause it to switch ratio. My initial thoughts on this are to get the player software to adjust aspect ratio only one time when playing a movie, so further detections throughout the video do not trigger another change. But of course there might be an issue with trailers etc that are in a different ratio, so maybe this wouldn't be perfect...


Ben.
 
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