[mythtv-users] OT: LED or Plasma (was Advice on choosing a TV)

Andre mythtv-list at dinkum.org.uk
Tue May 25 13:37:16 UTC 2010

On 25 May 2010, at 14:14, Paul Gardiner wrote:

> Andre wrote:
>> On 25 May 2010, at 08:41, Paul Gardiner wrote:
>>> Alasdair Macdonald wrote:
>>>> On 24 May 2010 19:05, Paul Gardiner <paul at laser-point.co.uk> wrote:
>>>>> Alasdair Macdonald wrote:
>>>>>> I don't hear any unwanted noise at all coming from my screen.
>>>>> Really?! Maybe mine is faulty. Have you tried playing a movie
>>>>> with the sound muted? The sound I hear changes with the picture
>>>>> movement. The sound comes from the back, so if you have something
>>>>> soft behind the set that may damp it out. I have mine wall
>>>>> mounted.
>>>> If I mute, and put my ear close to the (now wall-mounted) screen, in 1
>>>> or 2 positions I can make out quiet buzzes. If my ear is more than 6
>>>> inches from the screen, I can't hear anything. I guess the wall is
>>>> allowing any sound to multiply & bounce (not dampen) before it reaches
>>>> my ear; I consider the hardware near-silent.
>>> Mine seems to have quietened down now. I can still hear it but now
>>> only if I mute the TV and strain to hear it. Weird! Maybe it's part
>>> of burning in.
>> It used to be common that scan coil windings and linearity corrections coils in olde CRTs would vibrate until they had warmed and cooled a few times, had to melt wax into the odd one as a junior TV tech. Sometimes switch mode power supplies do similar, maybe that's what you were hearing.
> That exactly how it sounded. Reminded me exactly of the sound from
> switch mode power supplies. So I guess it figures it may have
> quietened and its not just my imagination.
>> Glad you like the TV, thought you would... I like the 600hz mode when it's working well but I can't tolerate it's failures, you should see some real 600hz video, actually shot at 600hz, wow! There's considerable interest in 300hz cameras as they can simultaneously output great 60hz, great 50hz and great super slomo too, I think I spotted one of the prototypes being used in Vancouver. Will be a long long while before we ever see a real 300hz live TV transmission but we should get the benefit of it behind the scenes around the time 1080p50 & 1080p60 transmissions start.:-))
> That's interesting. I wonder about a halfway solution sending 60Hz plus
> some reliable motion vectors that the receiver can use to improve
> interpolation.

It turns out it's actually really easy to send high frame rate video so no halfway houses are really required, 1080p50 needs no more bandwidth than 1080i50 less sometimes, 1080p300 needs little more than 1080p50, less sometimes, when the frames are clear of motion blur and little change to the next one they compress really well! As a handy little side benefit if there is a lot of sensor noise (which there will be at 300 or 600fps) that changes every frame the real picture doesn't so much, so the first thing that gets removed in compression is the sensor noise, proper noise reduction for free! 

Anyway even ye olde mpeg2 is using motion vectors (move this block of pixels by this much and this direction and change it like this) so motion interpolation software can deduce frames between provided it's seeing the mpeg2/4/h264 stream, that's why I'm more interested in uPnP DLNA playback in TVs than VDPAU, CrystalHD etc. It's also why the integrated DVBT/T2/DVBS/S2 receivers usually give better picture quality than an STB via HDMI, doing motion interpolation from 1080i or 1080p is much much harder.

I'm interested to try vdpau into a 3D capable display, some of them are able to accept 100/120hz input for 2D as a fringe benefit of the 3D capability, that will need a GT240 I think ;-)


> Paul.
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