video delay chips/circuits

Discussion in 'General Electronics Chat' started by relicmarks, Mar 28, 2008.

  1. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    who makes a cheap video delay chips or circuits?

    I'm looking for a cheap circuit or video delay chips that can take the video signals either VGA,S-video,composite,component,RGB and delay it in milliseconds but how?

    what are these types of chips and circuits called please?
     
  2. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    I have a audio delay cicuit that goes from 1ms to 20seconds , i tried plugging my RGB signal or composite signal into the input of the audio input , it didn't work

    How can i convert my RGB video signal down to a audio signal? what type of convert can i use to convert video signals RGB or composite into audio frequencys? like some type of AM or FM encoding or modulation i would need?

    Audio is from 20hz to 20K

    Video composite is from what to what?
    video RGB is from what to what?
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    Your video signals are relatively high bandwidth.
    Audio signals are relatively low bandwidth.

    Compare an audio cassette tape to a VHS video cassette tape. You'll notice that the videotape is far wider than the audio cassette. This is because the video requires much more bandwidth than the audio does. Even a VHS video cassette does not have sufficient bandwidth for your computer monitor or HDTV signals.

    It would take quite a bit of processing power and memory to do what you want to do.
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    A composite video signal needs about 4.5 MHz bandwidth. RGB depends on the framerate.

    Video tape recording is done with the read/write head moving across the tape to allow for the much higher signal rate. The tape moves enough slower that achieving milliseconds of delay would present a significant problem.

    Recording the video with a video A to D chip and playing it back with a video DAC after the desired delay is probably the most practical way to do it.
     
  5. Audioguru

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    Dec 20, 2007
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    Composite video from an old TV goes from DC to 4.2MHz. High definition video goes up to 37MHz. A video monitor video signal might go up to 50MHz.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    A high-quality audio sample is recorded at a 44kHz rate.
    With the not-so-great old NTSC video standard bandwidth being 4.2MHz, you need nearly 100x the bandwidth of audio just to get even poor video signal quality.

    I drew up a very crude representation of how differently audio cassettes and video cassettes are recorded, just so you could get an idea of how much more data is required to reproduce video & audio vs audio alone.
     
  7. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    Composite video from an old TV goes from DC to 4.2MHz.
    Video from high definition TV goes up to 37MHz.
    Video from a monitor could go up to 50MHz.

    So from DC to 4.2MHZ or 50MHZ i need to convert this signal to 20hz to 20Khz but how can i do this

    if the video signal is DC to 50Mhz modulated ,how can i convert it so the video signal modulation is still at DC to 50Mhz but its converted to 20hz to 20Khz?

    would i just have to change the carrier frequency? or AM frequency? how can i do this?

    My audio phase shift circuit input needs a 20hz to 20khz audio signal , but my video signal is DC to 50Mhz , how can i make the input see the video signal , some how i need to DITHER the signal you guys think?
     
  8. Audioguru

    New Member

    Dec 20, 2007
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    You want to delay video. So use a video delay circuit, not an audio delay circuit.

    If you ride a bike on the runway at an airport, will the bike fly?
     
  9. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    ya but can't i compress the video's bandwidth or convert the bandwidth DOWN to 20hz to 20Khz in the bandwidths range of audio?

    I'm trying to encoded or modulate the video's bandwidth to FAKE or "mimic" a audio's signals bandwidth but how can i do this? i need some special type of converter

    video bandwidth converter to audios bandwidth i need , but how and what will do this ? or in theory try to explain?
     
  10. Audioguru

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    Dec 20, 2007
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    You are dreaming and you don't understand electronics.
     
  11. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    they did it with audio converting to MP3 its compressing and encoding

    why not with video?
     
  12. Audioguru

    New Member

    Dec 20, 2007
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    They can compress video. It looks like big and little squares moving around.
    Years ago they made video phones. You needed to hold still for 20 seconds for it to make a fixed picture. Now it takes a picture quickly then plays it back slowly one pixel at a time.
    It is called, "Jerky Vision". The ones that don't jerk are called, "Fuzzy Vision".
     
  13. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    how would u delay video then? in a very cheap way or some tricks to do it?
     
  14. SgtWookie

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    Jul 17, 2007
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    relicmarks,
    When they did it with audio, converting it to MP3 format, they took a signal that was ALREADY low bandwidth, and compressed it by removing a lot of the redundant data.

    Now with video, there is SOME redundant data, and perhaps some of that data can be compressed with advanced algorythms. You might even get the output to 20% of the original size, without absolutely destroying the signal quality - although it would be very noticeably degraded.

    But even after compression, the resulting signal would still require 20 to 40 times as much bandwidth that is available in an audio circuit.

    What you want to do can be done - but it's not going to be cheap.

    If you want cheap - wait a few more years. Prices are still coming down.
     
  15. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    wait i don't get whats to much different than a audio delay chip VS a video delay chip

    The video delay chip should be a Bucket Brigade Device right? what is so much different than a video delay circuit VS a audio delay circuit/chip?
     
  16. beenthere

    Retired Moderator

    Apr 20, 2004
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  17. Audioguru

    New Member

    Dec 20, 2007
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    Has a semiconductor manufacturer made a "bucket brigade" IC since 20 years ago? and its bandwidth was barely enough for audio?
    Nobody made a video bucket brigade video delay IC.
     
  18. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    Then how did they do analog video delays then? using what type of IC chip ?
     
  19. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    You can transmit still pictures over the audio bandwidth using slow scan TV techniques, but I don't think that's what you want to do. What you want to do is impossible, as you have already been told several times.
     
  20. Wendy

    Moderator

    Mar 24, 2008
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    That compression you are talking about would remove so much information off the video signal that there wouldn't be anything left. I can understand the confusion, seeing how video is compressed for computers is pretty amazing. Thinking about it, that is the absolute best that has come out, as phone lines are nothing but audio and you can see low res video on there. But the video images involved with computers aren't just digitized, they are totally reformatted, converted, and compressed using some really advanced algorithms, and use huge amounts of computer power to get to where they are. Definitely not simple electronics.

    I used to see kids toys that did something similar to what you are talking about, using an audio tape for video. It had a display that was B&W and had a 256X256 pixel resolution, and didn't use anything like a video signal.

    Thinking about it, to do what you want to do could be done with a computer, if you are desperate enough to build a relatively high end machine for it. Possible, but good luck with the software.

    Sorry if I'm repeating some of what has already been said, I missed the second page in this thread.

    In any query like this it helps to know why you want to do what you are trying to do. Sometimes there are other ways of accomplishing the same thing.
     
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