Lip synch fix for 1 frame delay

Discussion in 'AV Receivers & Amplifiers' started by dyson, May 27, 2004.

  1. dyson

    dyson
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    I have a Denon AV2803 receiver. I need to introduce a 1 frame audio delay to compensate for a tv which delays the image by 1 frame.

    I understand 1/25th of a second (PAL 1 frame) is about 40ms.

    The Denon AV2803 has a Delay Time function for the speakers, but they are in metres (or feet). I just need to be able to calculate how many metres equal 40ms delay and this should give me the delay I want - without having to buy another receiver. (Hey, I only just bought this one!) I now realise I should have bought a receiver with a master - or even component specific - delay, but it is too late now.

    Please help. Is there a chart that could help me work this out?
     
  2. karkus30

    karkus30
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    looks like an easy calculation.

    Sound travels at about 331m/s in air

    therefore in 1000/th of a second (1m/s) it will travel 0.331 metres

    x by 40 for the total delay 13.24 metres

    any takers............I will start with a vowel Bob and a .........
     
  3. Jasonjo

    Jasonjo
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    Unfortunately most amps dont let you set a delay this big...normally 5-6m is the limit...:(

    JJ
     
  4. dyson

    dyson
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    Luckily the Denon AV2803 Delay Time on speakers goes up to 18 metres. This could well be a solution for some people. Anyone else care to corroborate karkus30's figures?
     
  5. Jasonjo

    Jasonjo
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    Maths looks good...

    However I think most people use 80-100ms for their audio delays if I remember correctly...

    JJ
     
  6. dyson

    dyson
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    I've made the adjustements and I'm keeping an eye on lip synch.

    In the mean time - my wife pointed out that if I set the delay to increase by metres (i.e. 13.2 + real distance) won't that decrease the delay? As in the function is really designed to match varying speaker distances from the listener. So if if I am telling it that all the speakers are 13.2+ metres away, isn't it going to decrease the delay thinking the sound has to travel further - hence start earlier to get to the listener?
     
  7. dyson

    dyson
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    I have traded-in my Denon Amp AVR-2803 for an AVR-3803, as this has a dedicated Time Delay in milliseconds specifically designed to fix lip synch issues. (The speaker delay function in the 2803 simply couldn't manage the type of delay correctly - it is more for surround fx subtlety.)

    So... an extra $AU800 to fix the problem. Hmmm. Hopefully this thread will alert others to the perils of modern day image processing and lip synch issues.

    As my Sony KVHR36M31 86cm 16:9 CRT introduces a 1/25th of a second delay to the picture, I have added a 40ms delay to the audio. This has solved the problem. :)
     

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