[mythtv-users] Bob2x with wobbling OSD even at 50 Hz

[Dan Seddon]

Jens Axboe wrote:
> On Thu, Jun 29 2006, Dan Seddon wrote:
>   
>> Jens Axboe wrote:
>>     
>>> On Wed, Jun 28 2006, Tino Keitel wrote:
>>>   
>>>       
>>>> Hi folks,
>>>>
>>>> I managed to get a 50 Hz screen on my TFT to get a stable picture with
>>>> the bob2x deinterlacer (I use a PAL DVB source). However, it's mostly
>>>> the same as before with 60 Hz. The OSD is only stable for a few seconds
>>>> maximum, then it starts to flicker again.
>>>>
>>>> What should I do to get a stable picture with bob2x?
>>>>     
>>>>         
>>> I'm in the same boat, 50Hz DVB and bob deint causing flicker on
>>> horizontal lines such as logos (at least that's where it's most
>>> noticable). On HDTV you don't see it much, on STDV it's quite horrible.
>>>
>>> So I'd very much like to know what can be done about this as well. Bob
>>> deint is the only usable deinterlacer it seems, the others all look
>>> horrible in comparison.
>>>
>>>   
>>>       
>> Unless you have some other problem, this is a side effect of bob 
>> deinterlacing (the fact that Tino finds it OK for a few seconds if 
>> baffling) - where the detail is small such as small fonts.
>>     
>
> That's the only issue I have, apart from that picture quality is perfect
> with bob. The first few seconds is the same here for me, nothing
> changes from the moment the image is first displayed.
That's really weird - I'm pretty sure you *should* see it, so maybe you 
do have something else going on??? Unless the bob doesn't start doing 
it's stuff for while.

>> Each field is generated (on alternate frames) by interpolating the 
>> neighbouring fields - in the case of a hard edges (such as in a font) 
>> this will bleed in to the interpolated field (which being on every other 
>> frame will cause a jitter), it would only possible to get rid of the 
>> problem by overlaying this detail after the deinterlacing has been done 
>> (maybe that's possible in the case of the OSD???) or with some fairly 
>> heavy duty image processing. Most broadcast text should be big enough 
>> not to be made too horrible by interlacing - I can't say I get bothered 
>> by it much although it's there. The OSD is a bit nasty at it's default 
>> size, but I've made mine much bigger and it's now fine. The jittering is 
>> still there - but it's much less perceivable when a field is small 
>> relative to the size of the text, which is why you don't see it much in 
>> HDTV. My view is that the benefits of bob-deint out way this problem by 
>> far - so stick with bob and make you OSD bigger.
>>     
>
> OSD I can live with, but watching eg the news with their box graphics
> makes it look pretty bad (reminiscent of earlier days of cheaper
> computer monitors running at too low refresh rate). I should mention
> that this is an LCD TV, perhaps it looks worse there than on CRT?
>   
That makes sense - I'm using a CRT and LCDs are hell of lot sharper (I 
say this typing at work on dual montior setup - 1 crt, 1 lcd). Also I 
sit on the Sofa quite well back - where I can't make it out,  it's there 
on news banners (but hard for me to see).