1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Lip-syns and Iscan

Discussion in 'Projectors, Screens & Video Processors' started by Johnty, Oct 24, 2001.

  1. Johnty

    Johnty
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    I`m posting this one again with different subject heading to attract a
    response

    My HC system is a Tosh 100E DVD (SVHS O/P) and sony VCR(composite O/P) fed
    to Sony AV amp(DB840) feeding an iscan with component input to sony 10HT .

    If I feed the received TV signal from VCR via iscan to PJ then I get
    serious lipsync
    problems.These are eliminated if I bypass the iscan and feed PJ on a
    composite link. I have also determined that if I use a seperate TV
    tuner(composite O/P) and feed that via the iscan -then no lipsync problem.
    Currently have no space to install seperate Tv tuner so need to solve
    problem.

    Any ideas why tuner O/P from VCR could delay video to this extent?

    ----------------------------------------------------------------------------
    -----------------------

    Also any comment why PJ picture is brighter on direct composite feed to PJ
    than when thru iscan.I believed that linedoubling would give increased
    brightness.

    So far on subjective viewing I am not seeing any great improvement with the
    iscan
     
  2. Roland @ B4

    Roland @ B4
    Active Member

    Joined:
    Apr 11, 2001
    Messages:
    2,238
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Reading.
    Ratings:
    +32
    Each transition has to go through a buffer which processes the signal then passes it.

    The Iscan is known to do this by a frame or two, the Sony will do the same as it remaps the image from the processor. I would image you are loosing 2 to 4 frames.

    The only way I can see round it is feed the signal straight to the Sony or to check your Amp to see if it can delay the audio sufficiently.
     
  3. Nick Beecham

    Nick Beecham
    Standard Member

    Joined:
    Oct 23, 2000
    Messages:
    132
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Location:
    Hockley, Essex, UK
    Ratings:
    +2
    OR buy a Pioneer DV 717 where the video is around 2 frames ahead of the audio so the error caused by the Iscan is cancelled out.

    Roland: Do you happen to know the frame delay caused by the Vigatec or the Rock+?

    Cheers
    Nick
     
  4. Gordon @ Convergent AV

    Gordon @ Convergent AV
    Distinguished Member AVForums Sponsor

    Joined:
    Jul 13, 2000
    Messages:
    13,978
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Living in Surrey, covering UK!
    Ratings:
    +2,779
    Hi Nick:

    Depends who you ask.... Vigatec has same de-interlacing chip as Iscan. Vigatec claim 4 FRAME buffer for working out de-interlacing. Iscan claim 4 FIELD. Bit of a difference.... Me, I think 4 Field makes sense but 4 Frame seems more realistic when you see the delay at times.

    Having seen the Rock Plus recently I can say that, on limited material I watched, it has no noticeable delay. At least none as significant as Vigatec. The Runco I'm playing with just now has no delay either but the Terranex over in the US has something like a 9 Frame delay I believe!

    All the best,

    Gordon
     
  5. Roland @ B4

    Roland @ B4
    Active Member

    Joined:
    Apr 11, 2001
    Messages:
    2,238
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Reading.
    Ratings:
    +32
    Hey, you could hear the bang of the gun and duck before the bullet got you!;)



    The Rock still has a frame or two but as Gordon says its not noticable. The S&W does it too but it doesn't take NINE frames.

    But you try taking a video frame looking at the last two frames and the next four and working out what is going to move. Oh and add a few million extra pixels too. and do it 60 times a second and see how many fames you need. these boxes are clever. the maths is (are)just unbelivable.
     
  6. RichardA

    RichardA
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Hi,

    Unfortunatley all video processing induces some delay!

    The Iscan Pro (Sage 503) chipset on it's own I believe induces around 4 fields but this is extended by a the scaler section, which has to use more memory to process, which will end up with a de-interlacer + scaler with about 4 frame delay.

    The S&W Interpolator uses our own single stage (i.e one memory block)processor and the total delay through the system is 3 1/2 FIELDS plus or minus 1 FIELD.

    The Teranex's 9 frames does not seem unusual with their processing scheme - in a broadcast domain audio delay lines would be used in the system anyway to compensate.

    As a note, the other box I work on - Archangel (it's a film and video realtime restoration system) the delay is in excess of 15 frames - now that's lip sync error!

    Sadly I don't know of any readily available solution to this problem except for the high end Meridian type processors that have a lipync delay - I could offer you our nice Analog or digital (AES/EBU)delay lines but I don't know of any AC-3 delays comercially available.

    Sorry I can't be of more help,
     
  7. Jenz

    Jenz
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Actually there is a solution that I have that may be applicable but sadly it's not cheap :(

    I use a Rock+ Video Processor connected to an Arcam DV27 DVD Player. As the Arcam is Progressive Scan (NTSC and ahem wink wink say no more P*L) you can set a Progressive delay in the Audio output.

    As a result there's no issue :D

    Of course that combo is not cheap...
    Regards Jenz.
     

Share This Page

Loading...