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Picture quality - help please

Discussion in 'TVs' started by online, Feb 11, 2004.

  1. online

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    Apologies for asking a basic question, but I'm new to this. I've just bought a Loewe TV (a Xelos). The initial reason for doing so was primarily design, but the excellent picture quality was also a factor.

    Now, having had it for a week or so I can see a big difference in the picture between DVD, Freeview and analogue. DVD is best by a mile, and usually analogue looks a bit better than Freeview. We get a good analogue signal (we can see the transmitter) and the Freeview box, although a Goodmans, had had good reviews.

    The question is, is this what I can expect, or is there anything I can do to make the broadcast picture quality the same as DVD? Most people with 'ordinary' TVs would say that the broadcast pictures are just fine, but I want to be sure I've got the best I can.

    Thanks for your help
     
  2. LV426

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    In what way would you say, the PQ of a digital broadcast, is inferior to that of DVD.

    (I'm not denying that it may be - just trying to find out what you would like help in fixing.....)
     
  3. online

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    Thanks for the response. I'd say that the broadcast images have less detail and are less 'real' than the DVD. The Freeview images sometimes look a bit 'digital' - similar to an over-compressed JPEG photo.

    As I said in my original post, the broadcast images are pretty good - better than most TVs I've seen. It's just that the Loewe + DVD quality is even better. What I'd like to know is if it's possible to get the same sort of quality from broadcast, and if so what I need to do.

    Thanks again for help with such a basic question - my Loewe has made me look at TV with a much more critical eye!
     
  4. lynx

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    Are your video outputs set to RGB where applicable (DVD, Freeview) and being sent to a corresponding input on your Xelos ?
     
  5. LV426

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    OK here is some information, and a guess.

    DTV broadcasts and DVDs alike use compression techniques in order to squeeze the huge amount of information needed to get a coherent moving image on your screen into the least amount of data.

    Any such compression technique will degrade the original source to an extent. And the extent depends on how compressed it is.

    The degradation occurs when (given an unlimited amount of data) the most data would be needed. Where there is a lot of fine detail movement, or in a longish soft dissolve (crossfade). Either of these examples involve much or all of the image changing from frame to frame -and that's what demands the most data.

    Data compression usually involves 'capping' the data rate to a given value. When the data required is greater than the 'cap' artefacts begin to arise - pixellation typically (moving coloured areas cluster together into larger coloured blocks momentarily).

    The theoretical definition of a DTV signal is the same as that of a DVD of the same TV standard (eg. PAL 625/50 vs PAL 625/50).

    BUT: The data rate 'cap' is much lower on DTV than on DVD, so as to make 'better' use of the number of transmitter channels (muxes) available.

    Therefore, DTV is much less able to cope with large amounts of change in the image - has a greater tendency to pixellate.

    Compression is applied at source and there is nothing you can do locally to get over its artefacts.

    One of the 'features' of a very high quality TV is that it will have a greater tendency to reveal shortcomings in the source. I guess that's what you are reporting.
     
  6. online

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    Thanks to both of you.

    The connections are all correct (or I think they are). Nigel's descriptions correspond closely with what I'm seeing - the effects are greater with a busier image - so I guess I'd better get used to it and start looking at the content rather than the technology.

    Is satellite better than Freeview, or are the compression effects the same?
     
  7. online

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    Thanks to both of you.

    The connections are all correct (or I think they are). Nigel's descriptions correspond closely with what I'm seeing - the effects are greater with a busier image - so I guess I'd better get used to it and start looking at the content rather than the technology.

    Is satellite better than Freeview, or are the compression effects the same?
     
  8. MartinImber

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    Sattelite is supposed to be worse.

    I have a top end 1st gen DVB-T tuner within my IDTV and DTTV is excellent, within limits it is as good as DVD - the limits are the capped bit rate ending up in occasional blocking.

    Try a different box RGB (S-ony/Pioneer/Netgem) connected or a component box if you have a component suitable TV.

    Edited to remove a funy link
     
  9. LV426

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    A direct side by side comparison of BBC1 and C4 between $ky and Freeview indicates to me that Freeview is noticeably much better (less compression artefacts). The same may not be true of the premium/subscription channels on $ky - no way of comparing like for like.
     
  10. Falp

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    Wich model of Xelos do you have?

    if it's a 32" model turn DNC and DMM on and resolution to 3.
     

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