Analog composite audio converted to Digital Audio (SPDIF)?

[sbook73]

I just recently purchased a new HDTV widescreen. When connecting everything I had the optical audio from the dvd player directly to my stereo reciever then the optical audio from my cable box directly to my stereo reciever (which I had to use composite cables as well to get sound from my 0-70 channels) as well as composite cables from my VCR to the stereo. So when ever I swapped video input on the TV I also had to swap audio channels on my receiver.

Then I saw the SPDIF output on the back of my TV. Which is strange because there are no digital audio inputs to the tv except the HDMI but I use component video cables for my HD. So i went ahead and tried connecting everything to the tv via composite cables and then connecting the tv via coaxial from the spdif to my stereo receiver and it doesn't seem to lose anything? Is this posible? How do it work does it take the analog signal from the composite cables and convert them to digital? And if so am I losing anything in the process? Will I still be getting 5.1 surround? Someone please help I am over my head.

 

[MDS]

The TV has a digital output most likely because it has a built-in atsc tuner. If you were using the tuner in the tv with an antenna you could then use the coax s/pdif to connect to the receiver so you would get digital sound from the internal tuner.

If I understand correctly, you now have the dvd player, cable box, and vcr connected to the tv with analog cables and one single coax cable from the tv's digital out to the receiver. So you only have to select one input on the receiver to hear all sound. That tv must convert analog inputs to digital if that is the case.

You will still get surround that way but not the original DD or DTS from the dvd player or cable box. If the cable box is receiving a digital signal or the dvd player is playing a disc with DD or DTS and you connect those devices to the tv with analog cables, they will convert the digital signal to 2 channel analog which is now sent to the tv. The tv in turn will turn it into 2 channel digital and send it back to the receiver. If the receiver is set to use a matrix decoder like PLII, it can turn it into 5.1.

Your setup is actually backwards from the way it is most often done. You want all audio to go to the receiver and a single video connection to the tv, that is if your receiver can switch video. Then when you switch the input on the receiver, the video will switch too and you never have to touch the tv input. If you aren't using the tv's internal tuner, then you don't need to use its digital out. The way you had it originally is the way to do it if your receiver can switch video - you don't need to get audio to the tv unless you need to use the tv speakers.

What tv and receiver are you using?

 

[sbook73]

I just bought the Philips 51" HDTV (51PP9100D) and am using an old Aiwa receiver. The receiver does not have the component in and out. It does have two optical digital ins and one coaxial digital in. The TV does not have that many av connections to begin with.

So basicly the way I have it now I can still get the 4 channel surround sound but I will not get the full 5.1?

 

[j_garcia]

You cannot get digital sound at all the way you have it hooked up. You've taken a step backwards, IMO. The optical connections were giving you true multichannel digital surround (when available for the HD box). Now, despite a digital connection, you are only going to get stereo from the TV from which you can use a DSP to "simulate" surround. You would need to use HDMI from one of the other devices to get surround from the TV, and then it would only be for that device.

If you want to switch everything via the receiver, you will need a receiver that does more than just switch video, you will need one that does transcoding of the signal so it can accept a variety of inputs and transcode them to component or HDMI. Pretty much all receivers will switch video, but not all can transcode from one type to another.