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Question on VideoFormatControl.DFC_ constants...

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ttwdev
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Joined: 2009-07-27
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Hi -

Am I mistaken in thinking there's no difference between DFC_PROCESSING_FULL and DFC_PROCESSING_LB_16_9 when the input is 16:9 and the output is 4:3? Seems like they'd both result in 16x9 letterbox - black bars on top & bottom.

Some diagrams illustrating the expected effect of all the DFC constants in various scenarios would be extremely helpful. Barring that, I'm hoping for some more info here.

Thanks.

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sglennon
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Joined: 2008-12-17
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This is a pretty thorny area. I believe that the meaning of DFC_PROCESSING_FULL is "take the full decoded picture and have it fill the full output frame".

This means that (for example) a stream encoded at 720x480, signalled as 16:9 would output filling the full active region of the video output, regardless of the display aspect ratio.

In the same example of 720x480 signalled as 16:9 with DFC_PROCESSING_LB_16_9 with a 4:3 display would be scaled down to have black bars top and bottom.

This is documented in OCAP 1.1.2 section M.2.1 "org.dvb.media.VideoFormatControl". It does not seem to specifically relate to the output - in particular it says for LB_16_9 that it scales into a letterbox (relating to the active video), so applying this DFC for a 16:9 TV would be bad.

Hope this helps.
Steve