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Suggestion on old stereo and HDMI

n3pla2000

New Member
Initial Information
My stereo receiver is an A/V unit that has composite video for some of it's selections, these selections are LD, TV, VCR1, and VCR2. It also of course has a single composite video output. It is possible to switch the composite video separately from the audio, but normally what ever selection is made to the audio source also selects the video, if that component ALSO has a video input. So here is my problem:

  1. Modern video devices use HDMI
  2. Converting 4 HDMI signals to composite degrades the signal.
  3. I then would have to convert them back, also a point of degradation

Here is what I wish to do

  1. Be able to use a mix of older composite sources and modern HDMI sources
  2. Have the stereo be able to switch these sources
  3. Have audio from both HDMI devices as well as from the composite video sources be passed through to both a HDMI and composite destinations.

Ideas on solutions

  1. I could simultaneously pass tones using four DTMF generator chip to the four video inputs of the stereo, then use a decoder on the video output to determine which of the four inputs were chosen by the stereo. Use the binary output of a DTMF decoder to control an HDMI switch. This would then require me to strip audio from the output from the HDMI switch. Some switches already do this for me, some do not. It also requires to have a composite to HDMI converter for each composite device I wish to connect to the HDMI switch inputs. I would also need to tie the four left input, and four right input audio channels together since the switch would be the only audio source, possibly with an audio distribution amplifier.
  2. Again using DTMF input four tones to the stereo, this time using a single DTMF generator chip. Next use a counter to switch the generator between four sets of tones, while also using maybe 4066 chip to switch tones 1 through 4 to their respective video inputs. Again stripping audio and sending it to all four stereo inputs, also using again converting composite inputs to HDMI. If I use this solution I am unsure how fast I can switch between tones, and still have a decoder reliably decode them. Too slow, and the lag between switching from one audio source and video source other would be too great, too fast and the decoder may not properly decode. Also I can tie the rows and columns together as follows, so both the high and low tone of the DTMF signal will change at the same time, but does that make decoding more reliable?
    1. Row 1 + Column 1 tied together outputting tone "1"
    2. Row 2 + Column 2 tied together outputting tone "5"
    3. Row 3 + Column 3 tied together outputting tone "9"
    4. Row 4 + Column 4 tied together outputting tone "D"
  3. Generate a fake video signal, with an embedded signal that can be detected as one of four and use that as one of four and detecting that at the video output. This idea seems overkill but maybe there is something out there that makes this easier than is sounds.
Any ideas or suggestions? This project will take a while since I'll have to send for each part I use, and funding is out of my meager pocket...

And no I am not replacing the unit as suggested by someone and as per the above statement about meager out of pocket funding.
 
Last edited:

gophert

Well-Known Member
Most Helpful Member
Use your TV as the HDMI switch (all components connected to TV's HDMI except receiver) and send the audio out from the TV via the fiber optic connector to your AV Receiver. The fiber optic can carry the multichannel audio signal for Dolby digital/DTS so no losses.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Use your TV as the HDMI switch (all components connected to TV's HDMI except receiver) and send the audio out from the TV via the fiber optic connector to your AV Receiver. The fiber optic can carry the multichannel audio signal for Dolby digital/DTS so no losses.
Unfortunately that doesn't work.

The optical out on a TV generally only provides the full range of multi-channel audio from it's internal digital tuner, aux inputs (such as HDMI) are down-converted in the TV and only offer a MUCH reduced audio output, often only stereo or ProLogic.

The answer is to dump (or sell - if you can) the old amplifier, and buy a new one to do what he wants - as it has labels for Laser Disk and VCR it's a seriously old antique!.
 

n3pla2000

New Member
I would NOT ever dump this receiver, too much invested including 3-100 disc changers, turntable, equalizer, dual cassette, et cetera. All of these use the same remote signal since the units also have connections to tie together all units remote signals. Also, although I can find other similar units, some older some newer, I rarely see this one, and when I bought this unit NEW in 1996, LDs were already mostly history. Also many newer stereo's do NOT have features this one has, unless I by an expensive unit, even some of theme do not have Dolby and/or ProLogic. Besides this unit is flawless, not a reason to replace it, and none of you actually answered the question I asked. Seems simple enough.
 

gophert

Well-Known Member
Most Helpful Member
Unfortunately that doesn't work.

The optical out on a TV generally only provides the full range of multi-channel audio from it's internal digital tuner, aux inputs (such as HDMI) are down-converted in the TV and only offer a MUCH reduced audio output, often only stereo or ProLogic.

The answer is to dump (or sell - if you can) the old amplifier, and buy a new one to do what he wants - as it has labels for Laser Disk and VCR it's a seriously old antique!.

My Sony says there is Dolby Digital Plus output on the optical output.

 

Nigel Goodwin

Super Moderator
Most Helpful Member
My Sony says there is Dolby Digital Plus output on the optical output.

As I said, there's only a very limited number of audio types available from the optical output, other than from the internal digital tuner. And the page you linked to actually says:

"When receiving the Dolby Digital Plus audio, the TV is designed to mute audio from the DIGITAL AUDIO (OPTICAL) OUT jack. "

It's really a very confusing and difficult situation, and is almost impossible to predict what 'might' actually work.
 

n3pla2000

New Member
Then why are you asking? The more you know, the more challenging you understand. Good luck.
I am asking a specific question, and seeking answers to that question, not answers to questions I am not seeking answers to.

If I had schematics for this unit, I might have asked about hard wiring to the internal switching of the stereo send signals to a HDMI switch, so the stereo could control it, and mount it inside since the unit has plenty room inside, and space on the back for HDMI jacks. On the other hand I might not have, as this stereo is worth a lot to me and is not replacible.

Why am I being questioned about what I seek to do, and why, when an answer to how to do it will suffice? This is getting ridiculous. If you do not have an answer to the question, please do not give "solutions" not involving the initial question. This is like asking can I paint my bike red using paint, and being told "No, you have to replace the entire frame. I know my idea can be made to work, but not sure my method is the best solution and am seeking advice, information, and suggestion along that line. Not seeking to throw out the baby with the bath water.

BTW. What does: "The more you know, the more challenging you understand." even mean? I think it was miss typed, and I am curious...
 
Last edited:

gophert

Well-Known Member
Most Helpful Member
Why am I being questioned about what I seek to do, and why, when an answer to how to do it will suffice?
Because we are here to solve the problem you really have. We are not here to solve the problem you think you have... and we are definitely not hear to solve your proposed solution.
 

unclejed613

Well-Known Member
Most Helpful Member
HDMI hardware isn't something you can retrofit to older equipment. it is designed that way. the whole idea behind HDMI is to eliminate analog conversion of video completely. there are equipment identification codes used on all HDMI equipment, which identify the video/audio formats the equipment will work with, and what that piece of equipment can do. there are also embedded encryption keys unique to each implementation of hardware. if it comes to the attention that a manufacturer is somehow providing a path to analog conversion of content, that manufacturers HDCP keys are revoked.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
What make and model is the existing AV receiver, so people can examine its capabilities?
 

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