stereo audio delay

Discussion in 'The Projects Forum' started by okeytheone, Nov 15, 2009.

  1. okeytheone

    Thread Starter New Member

    Nov 15, 2009
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    Hi guys, this is my first post, as i have been looking at this site and it looks prety impresive.

    I have various home cinema systems connected to my tv, and seem to have a lip sync problem, looking at other forums, this seems to be quite common.

    I was wondering is there a simple circuit out there where you could put it inline with the audio in on the home cinema, so to create/add a delay.

    The delay must be variable between 0 - 4 ms.

    your thoughts please
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    Here's a link which describes a method to create audio delays programmatically:
    http://www.cse.msu.edu/~cse471/variabledelays.html

    It also describes the old-fashioned way of creating delays, using a speaker in a long tube with a microphone on the other end.

    For the digital delay method, you would require a computer with a pair of sound cards, or a microcontroller capable of processing digital audio data at a 44kHz rate.
     
  3. okeytheone

    Thread Starter New Member

    Nov 15, 2009
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    the problem i have is with the speech on the tv not in sync with home cinema system.
     
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    One could start with a dsPIC and create a delay line, but the audio quality may suffer, depending on definition of "fidelity". I would guess that if the sync is an issue with many people, there is a DSP product for correcting it. Surround Sound processors need delays, it is just a matter of having a "Master Delay". My receiver has delay options for inter-channel balance, but no setting for offsetting the entire signal.

    It would sound fine to most of the population, but there is always a group that can allegedly tell the difference between the type of copper used in power cords or speaker wire. I myself wouldn't notice a 5 millisecond delay between soundtrack/video, I've played with delays in BSPlayer on the PC watching a movie and can't notice much until it is in the realm of 100 milliseconds.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    I understand that.

    You could create an audio delay using a speaker, a tube that telescopes, and a microphone with suitable amplifier for the speaker, and preamp/amp for the microphone.

    Or, you could do it digitally - but that's not so simple.

    I did a search for audio delay equipment, but there doesn't seem to be a lot out there right now. You might search for lip-synching software.
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
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    My oldest says that he sees a delay between lips moving and the sound. If this is the case, then delaying the sound only makes the problem worse. The cure there is a video delay.
     
  7. okeytheone

    Thread Starter New Member

    Nov 15, 2009
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    that sound's about right to me then, now that puts a different light on it, i watch sky hd using hdmi in to the tv, now how the hell do i delay that.
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
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    Can you assign some post number to "that"? Hard to tell which problem you have.
     
  9. BMorse

    Senior Member

    Sep 26, 2009
    2,675
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    Are you running the audio through a Home Theater Surround Sound receiver?? On my receiver, there are actual delays you can set up for the different channels to accommodate for distance of the viewer from the speakers..... maybe yours is set with too much delay??
     
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