complectus Posted April 3, 2007 Posted April 3, 2007 Hi, I'm about to buy a TV & an upscaling DVD player & I already have an HD PVR STB and I've just realised that I'm not going to have enough digital inputs on my receiver. I'm wondering whether, if the DVD & PVR are connected to the TV via HDMI, & the TV has an audio optical-out connected to my receiver, will all the information from each source reach the receiver in its original form? Will the TV attempt to decode it & perhaps downmix it to stereo? The TV I will probably buy is the Panasonic 50PX600A, or maybe the new 70/700 if I can wait that long... Thanks.
Zacspeed Posted April 4, 2007 Posted April 4, 2007 Why cant you connect the video side of things direct to the TV from the DVD player and connect the audio (optical cable) straight to the receiver? Your method seems fair though. I take it by running both HDMI into your TV you only need the one optical cable to the receiver? I wouldnt think that it would down convert the audio signal at all. But I guess you'll never really be sure if the audio signals/channels are processed at all. ie Multiplexed etc. (MUX/De-MUX) Im not sure if your receiver does this, but on my Pioneer 7.1 system it lights up which channels are in use, ie I can tell if a DVD is stereo sound, 5.1, DTS, 6.1 etc as each channel will light up when its in use. If you can get a copy of Digital Video Essentials and run all the test sounds etc through it that will be able to give you an idea. As far as losing quality, you wont be able to tell really, but I highly doubt it & any loss would be negligible. Audio signals arent as complicated as video. I just wonder how the TV converts a digital HDMI audio signal to the pulsing optical fibre in the optical cable out socket. (ie how it converts the digital electric pulses to optical pulses)
aztec Posted April 4, 2007 Posted April 4, 2007 I don't believe the TV routes the input sound through to the optical out.
complectus Posted April 4, 2007 Author Posted April 4, 2007 Why cant you connect the video side of things direct to the TV from the DVD player and connect the audio (optical cable) straight to the receiver?Your method seems fair though. I take it by running both HDMI into your TV you only need the one optical cable to the receiver? I wouldnt think that it would down convert the audio signal at all. But I guess you'll never really be sure if the audio signals/channels are processed at all. ie Multiplexed etc. (MUX/De-MUX) Im not sure if your receiver does this, but on my Pioneer 7.1 system it lights up which channels are in use, ie I can tell if a DVD is stereo sound, 5.1, DTS, 6.1 etc as each channel will light up when its in use. If you can get a copy of Digital Video Essentials and run all the test sounds etc through it that will be able to give you an idea. As far as losing quality, you wont be able to tell really, but I highly doubt it & any loss would be negligible. Audio signals arent as complicated as video. I just wonder how the TV converts a digital HDMI audio signal to the pulsing optical fibre in the optical cable out socket. (ie how it converts the digital electric pulses to optical pulses) My receiver has only 3 digital inputs & I will have 4 digital sources (an XBox in addition to the 3 previously-mentioned ones). The TV I've been looking at has 1 audio optical-out & 2 HDMI inputs, all 3 of which are capable of carrying multi-channel audio. I was hoping that I could mute the TV's speakers & have the digital audio from the HDMI inputs pass straight through the TV's optical-out to the receiver. I'll be disappointed if, as aztec suggests, that's not possible.
Zacspeed Posted April 4, 2007 Posted April 4, 2007 If all else fails I beleive you can get a HDMI switching box that allows your HDMI inputs to go to the box and then from there you have one common HDMI cable that goes to the display. Im not sure how it works exactly but I remember looking into it a while ago for my receiver as I dont have HDMI on it, only optical. Then again im not sure if that leaves you with the audio problem still in which case you probably need the optical switching box instead which I just checked on google and they exist. They seem relatively cheap on ebay etc.
alanh Posted April 4, 2007 Posted April 4, 2007 All, For digital sound from HDMI, you need to get it from the display. The most displays store the image to display it. This means the sound will appear early. The HDMI, optical or coaxial from the display will be delayed by the time it takes to display the image. This will mean the sound amplifier will only require one input for any program with pictures and sound. You may wish to switch HDMI sources to the display to increase your choice, but since the HDMI also carries the sound it will be switched along with the pictures. AlanH
aztec Posted April 5, 2007 Posted April 5, 2007 My receiver has only 3 digital inputs & I will have 4 digital sources (an XBox in addition to the 3 previously-mentioned ones). If I understand correctly, you plan on connecting the PVR, DVD, XBOX and to the amp. What benefit to you is there in connecting the TV if the other three can be connected?
alanh Posted April 5, 2007 Posted April 5, 2007 astec, If you take the digital sound and decode it from its source, you must delay it to make the lip sync right. Otherwise the sound occurs before the picture. Some amplifiers will do this, however you do not need this feature if the display does it for you. I have not suggested you connect the other sources, DVD etc to the amp first unless it only is used as a vision/sound switch for the display. The easiest way is to use an HDMI switch box to give you 4 inputs to the display. HDMI carries both picture and sound so the single sound output from the display will only contain the sound of the program you are watching. Take the digital sound from the display and feed only it to the sound amplifiers. AlanH
complectus Posted April 5, 2007 Author Posted April 5, 2007 If I understand correctly, you plan on connecting the PVR, DVD, XBOX and to the amp. What benefit to you is there in connecting the TV if the other three can be connected? A number of HD channels are now broadcasting programs with DD5.1 audio streams. I'd like the TV's tuner to be able to send that to the amp directly. That makes 4 sources into 3 inputs. Also, my speakers are better than the TV's so 2.0 sources will sound better & will be distributed to all 6 speakers. Thanks to everyone who offered advice, especially alanh & his very informative remarks about delay... I hadn't realised that might be a problem.
uhf 2 Posted April 5, 2007 Posted April 5, 2007 While I'm not 100% sure, I think the output of the TV might only be in digital form from the built in HD tunner only. I don't think it would be a digital pass through, I do hope that I'm wrong, but I would check this out from panasonic. If it is a pass through that is the way to go, Good luck
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