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DVD: Sound And Vision

PolarknightPolarknight Posts: 890
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in TV and Home Entertainment Technology #1
Is the audio track on a DVD read seperately to the visual track? I ask this because this afternoon I dug out my copy of 'The 39 Steps' (1935, Lazerlight Edition in case it's a fault that others may have noticed) and noticed that at several points the picture pixellated and the sound would drop back maybe about a second, then after a while there would be further pixellation and the sound would catch up. This continued throughout the length of the film. I'd never noticed it happening before (and I've had this particular film for about 5 years) and am wondering if the sound is read seperately on a DVD player and, if so, is this occasional sound delay caused by dirt on the lens or what? Will my other DVDs be read in a similar way (haven't noticed it happening yet, touch wood)? Any advice would be welcome.

Comments

  • PolarknightPolarknight Posts: 890
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    #2
    Nobody knows the answer? It seems a simple enough question!!
  • SystemSystem Posts: 2,096,970
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    #3
    I'm not sure if this will be of any help to you but on my freeview box i encountered those same problems and a few people on here assumed it was caused by interference from something like maybe a thermostat on a boiler switching on and off or by a fridge door being opened. Apparently this carries interference through the mains. I'm unclear as to whether this would apply to your dvd playback but i guess it would be worth checking out.

    PS, if this is a ridiculous answer then maybe it will spur someone who does know a solution to finally post it on here for you.

    Good luck!!!
  • PolarknightPolarknight Posts: 890
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    #4
    No, not ridiculous at all. All input gratefully received. :)
  • gomezzgomezz Posts: 44,611
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    #5
    Two things to try. Play the DVD on another player; Try a different DVD on your player.

    As the audio is recorded on a separate track from the video track [1] then obviously it must be read separately. How the two are synched, I have no idea.

    [1] As can be illustrated by looking at a DVD on a PC using any of several utilities.
  • fat controllerfat controller Posts: 13,757
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    #6
    VERY long shot this, but it might hold a grain of sense - I remeber when DVD appeared (shortly after gas lights :D ) some users experienced problems when their players were playing dual layer discs. This problem usually manifested itself in the form of a pause of sound and vision whille the player moved from layer to layer. I also remember some gripes about audio playback, although I can't really remember specifics. As players progressed, these problems gradually disappeared - this was mainly due to the improvements in the CLV motors, and the DACs for both sound and vision. Basically, the motors got faster giving the ability to 'oversample' (read and read again) and the DACs also got faster, processing the data quicker. There are so may possibile answers to your problem - player getting too hot (processors slowing with heat as your PC will from time to time); Disc clamp a bit sticky, slowing the oversampling down; dirt on the lens; a flaw in the disc; and more. The advice above to try the disc in other players is the best place to start.

    Good luck :)
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