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How is this?

Discussion in 'Blu-ray & DVD Players & Recorders' started by martian1, Oct 29, 2002.

  1. martian1

    martian1
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    I have changed my 5yr reg 1 Pioneer player [moded to play reg 234] for a Sony ns900. I use a decent s-vid to scart lead and i am struggling to get the great picture improvement i was expecting, i tried RGB without a noticeable improvement so i am sticking with original lead as i nead RGB for Sky box.
    Would a £50 t0 £70 lead make a difference?
    Here is the thread topic main question... How the hell can i get a better Sky movie picture than my DVD players can muster? Its not all films just the decent quality movies eg Gladiator, Ryan, U- 571
    I have even tried putting the same movie in my player and comparing quality. I am watching predator now and it pis..s on my reg 1 disc... :confused:
     
  2. Big_AL007

    Big_AL007
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    Digital pictures whether from Sky or dogi terestial are nearly always better than DVD sourced material.
    I think it is a popular misconception that dvd is the best source you will ever see on a TV.
    Remember Sky and other broadcasters are using reference and above kit to source their output, coupled with a digital signal the end result should be great.
    I get similar results when listening to my digital radio tuner, it is easily the best quality sound source I have because there is a reference CD player at the other end pumping it out, apart from Chris Moyles's big mouth that is :p

    Hope this helps.

    AL
     
  3. steelej

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    You've got to be kiding. Sky digital picture is crap compared with DVD. Dodgy Compression artifacts all over the place. I've never seen a picture from Sky that is as good as DVD.

    John.
     
  4. rjw

    rjw
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    Sounds like you actually have a very poor DVD player.

    IME DVD is far superior to Sky digital.
     
  5. Ian J

    Ian J
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    I presume that you are connectiong the DVD player directly to the TV and not via an amp as some video throughputs on the amp do degrade the signal significantly.
     
  6. lmccauley

    lmccauley
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    And DVD producers are using reference and above kit to create the DVD, coupled with a digital signal. Both DVD & Sky use MPEG2 compression. DVD uses a higher bit-rate that can be adjusted for each scene to get least compression artifacts whereas Sky uses a lower bit-rate and does on-the-fly compression.

    If you are seeing a worse picture with your DVD player than your Sky box, then I would suggest that you check your connections and make sure you are using the best connection type you can (component or RGB, next best s-video, worst composite). If you are, then there may be a fault in your player.
    Very odd. Uncompressed CD should definitely sound better than compressed digital radio.

    Cheers
    Liam
     
  7. lmccauley

    lmccauley
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    My 5-year old Pioneer 606 produced a picture very nearly as good as my 545. I think you would find more of a difference if you were using a plasma or projector. I don't think you will find a lead making much difference.
    The picture quality of an individual film will depend on more than just the box it's played from. It will depend on the film master it was sourced from and the quality and care taken during encoding/compression.

    Cheers,
    Liam
     
  8. Squirrel God

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    I'm another who disagrees vehemently with Big_AL007.

    Broadcast radio and broadcast TV cannot hold a candle to DVD or CD and that's an absolute fact which, as Liam has said, is down to the bandwidth available for broadcasting and the compression used. The only explanation I can think of for Big_AL007's thinking is that he is watching DVD through a composite connection and Sky through an RGB connection - coupled with a DVD that is delivering poor results all round, perhaps also coupled with Ian's suggestion.

    I'm confused by Martian's post as he talks about improving his Sky Digital signal to get it as good as his DVD images, but then talks about Sky Digital being better than his DVD... :confused:
     
  9. michaelab

    michaelab
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    I also have to say that Sky Digital has about the worst broadcast picture quality I've ever seen, certainly FAR worse than DVD.

    I don't have Sky (not much use in Portugal!) but I'm in London at the moment and watched the Newcastle vs. Dynamo Kiev game on Sky Digitial in the pub last night and I happened to be very close to one of the 42" NEC plasmas in the pub so I could see the digital artefacts very clearly. It was absolutely terrible! Each player was walking around the pitch with their own MPEG halo surrounding them. Just to make sure this wasn't some weird plasma problem I checked on one of the other screens which was a normal 24" CRT TV and the artefacts were just as bad.

    How does anyone put up with it?

    Michael.
     
  10. rjw

    rjw
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    Because it's the best there is for me.

    I can't get terrestrial digital, and normal analog is terrible (local geography is to blame).

    To be fair though, watching footy in the pub is probably not an accurate example of Sky digital performance.
     
  11. michaelab

    michaelab
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    Well, I don't see why the artefacting would be any worse in the pub than anywhere else.

    Perhaps I was being a bit harsh - from a normal viewing distance it's pretty hard to spot the digital artefacts and it is of course a lot better than an analog signal with cr@p reception.

    If Sky didn't insist on beaming down 450 channels of junk along with the 50 worthwhile ones then it could use a higher bit rate which would improve things considerably. NTL Digital cable in the flat that I stay in when I'm in London is miles better than Sky (for picture quality).

    Michael.
     
  12. Ian J

    Ian J
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    That's because they were winning. I bet that the Manchester United players didn't have halos.
     
  13. martian1

    martian1
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    Can anyone explain what and how MPEG effects a picture, i thought it was a sound format. I have heard it mentioned in dvd player reviews but i dont have a clue what it is.
     
  14. michaelab

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    MPEG is a 'consortium' of interested parties which develops compression algorithms. MPEG is the video equivalent of JPEG for digital pictures.

    I can't remember all the ins and outs, a quick Google search will find loads. Can't remember what MPEG1 is but MPEG2 is used for video compression and is the format in which all DVDs are stored. It's also the format used for digital TV (whether terrestrial, cable or satellite). MPEG3 (usually known as MP3) is a compression format for music. MPEG4 is a newer (and better?) compression format for video.

    MPEG2 is similar to JPEG in the way it compresses pictures. Like JPEG it is a 'lossy' compression system which means that data is lost in the compression and what you get back after uncompressing is not exactly what you started with. In this way it can achieve incredible compression ratios (like 1:10 or even 1:20). Like JPEG it's also 'configurable' in that you can use different compression ratios for different quality. Obviously the higher the compression ratio, the lower the image quality.

    I don't know exactly how MPEG/JPEG image compression works but it starts by dividing an image into square blocks - the bigger the blocks, the better the compression but the worse the quality. Somehow the data in each block is then encoded in the form of some function which doesn't store the exact data hence the data loss (but very high compression ratio). During decompression the blocks are reconstructed from the compressed data. The exact way that works I don't know.

    However, the basic 'block' algorithm is what leads to so called digital 'blockiness' - when you can see the blocks in the reconstructed image. This applies to MPEG2 and JPEG. The smaller the original blocks, the better the image quality because firstly, smaller blocks are less noticeable and secondly, it's easier to encode the data in a smaller block accurately.

    As far as still images go JPEG and MPEG2 are pretty similar. However, MPEG2 also uses compression from frame to frame so that parts of the image that don't change don't need to be compressed all over again. Only parts of the image that need to be re-encoded. This is why moving objects are often surrounded by a strange blocky 'halo' where the compression algorithm has tried to detect what changed. Clearly, the more accurately this is done the less artefacts you get.

    There are probably some errors in the above but it's basically how it works. Others with more knowledge please feel free to correct me :)

    Michael.
     
  15. martian1

    martian1
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    Cheers for that. I have compared my new sony with my old pioneer player and it is better at detail and colours but slightly worse at producing fast moving images smoothly, seem to get a slight stuttering effect in image. My old player had macrovision disabled not sure about sony could this effect picture quality?
     
  16. michaelab

    michaelab
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    AFAIK Macrovision only has a very slight effect on picture quality that's usually not noticeable. It certainly is not connected with MPEG compression and wouldn't make any difference to blockiness or jerky movement.

    Michael.
     
  17. Squirrel God

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    As with all MPEG standards, MPEG-2 is actually a collection of standards for video and audio, not just video.

    MPEG-1 was the prior standard, again for video and audio.

    MPEG-1 was not designed with broadcast media in mind so it is not very error tolerant. It also does not cope as well with interlaced pictures as MPEG-2 (in fact, dealing with interlaced pictures was strapped on as an appendix in MPEG-1).

    There is no such thing as MPEG-3.

    MP3 is in fact, Layer 3 of the MPEG-1 Audio standard.

    MPEG-2 Audio is backwardly compatible with MPEG-1; therefore MP3 can be used to refer to MPEG-2 Audio, but only those elements which are equivalent to MPEG-1 Audio Layer 3. MPEG-2 also provides AAC (advanced audio coding) which significantly improves on MP3 compression.

    Yes, but again, not just video. MPEG-4 was developed with computer applications and mobile broadcasting in mind; it therefore deals not just with video and audio, but also with graphics, textures, speech and so on. To do this, it differs radically in how it compresses images and audio; therefore achieving vast improvements over MPEG-1 and -2 (it takes an "object-oriented approach" to it all).

    30:1 is typical for MPEG-1. MPEG-2 is even higher.

    Each frame of video is split into 8x8-pixel blocks. The blocks are then converted from the spatial domain to the frequency domain using discrete cosine transform (DCT). Lots of other stages are involved, including Huffman encoding and differential encoding; all of which help to improve the compression ratio.

    MPEG1 uses the same technique. So does MPEG-4. In fact, most video compression techniques use motion compensated prediction where movement of pixels or blocks of pixels are encoded as motion vectors. It's essential for getting rid of redundancy and thus reducing the overall bit-rate.

    Done :)

    Best site for finding out more is www.mpeg.org
     
  18. Ian J

    Ian J
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    Martian,

    Assuming that you are watching on a normal size TV and not a projector I would suggest that your TV could well be the culprit.
     
  19. martian1

    martian1
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    My tv is a Hitachi 43" rear pro set, thanks for clearing up the mpeg confusion guys. I think the player may be highlighting the rear pros limitations regarding very bright or dark images just a case of finding the right balance.
    I would just like to add that my statement regarding sky compared to dvd picture quality was a dig at some of the poor dvd prints on the market and not singing the praises of sky.
    On a great transfer there is no contest.
     

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