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:
Here is what I wish to do
Ideas on solutions
And no I am not replacing the unit as suggested by someone and as per the above statement about meager out of pocket funding.
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:
- Modern video devices use HDMI
- Converting 4 HDMI signals to composite degrades the signal.
- I then would have to convert them back, also a point of degradation
Here is what I wish to do
- Be able to use a mix of older composite sources and modern HDMI sources
- Have the stereo be able to switch these sources
- 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
- 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.
- 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?
- Row 1 + Column 1 tied together outputting tone "1"
- Row 2 + Column 2 tied together outputting tone "5"
- Row 3 + Column 3 tied together outputting tone "9"
- Row 4 + Column 4 tied together outputting tone "D"
- 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.
And no I am not replacing the unit as suggested by someone and as per the above statement about meager out of pocket funding.
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