[vdr] PVRINPUT plugin and "black/cinema bars"

VDR User user.vdr at gmail.com
Mon Apr 26 19:27:18 CEST 2010


On Mon, Apr 26, 2010 at 12:27 AM, Martin Dauskardt <md001 at gmx.de> wrote:
>> Doesn't matter which aspect ratio I choose, every channel under the PVR-500
>> displays with black (cinema) bars on the top and bottom of the image.
>
> I am pretty sure that your TV station broadcasts analogue TV not anamorphic,
> which means it "delivers" the black bars to prevent the aspect  ratio of a
> 16:9 content.

The 'black bars' are called letterboxing.  It's used to _preserve_ the
aspect ratio of widescreen content on 4:3 displays, not prevent it as
you've suggested.

> Unfortunately there is no way to detect the incoming signal (Tuner or extern).
> Therefore it is not possible to automatically choose the right setting.

Sure there is, just look in the mpeg headers.  If for some reason that
flag isn't set correctly, you can also use the resolution along with
some simple math to calculate the aspect ratio.

>> Any ideas how to remove these?
> The driver does not support clipping/cropping. We will always encode the whole
> capture size. If there is already a bar, it will also be in the encoded
> stream. You could try to use the zoom mode of your TV.

You _could_ write some functions to detect and remove letterboxing,
though I don't know anyone motivated enough to actually do it.

Cheers



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