HDMI help

March 11, 2011 1:29 PM

What's the difference between using A/V receiver to do switching (all HDMI) and using HDTV to do it?

Is there a difference? I can connect three sources (cable box, blu ray player and Apple TV) to receiver with three HDMI cables and then connect monitor with HDMI cable. Or I can connect monitor to receiver, then connect the three sources to the TV. I can't seem to get any HDMI all on/all off going either way.

posted by fixedgear to technology (13 answers total)

What my friend told me was that hopping from the receiver to the TV could cause degradation to the signal - but I have yet to see anywhere with proof of that. From what I understand, because the signal is digital, it does not have the same degradation problems as analog signals. This thread on avsforum.com seems to agree.

The difference I see is that with your receiver, you can control both the sound and the video with one remote, whereas if you go through your tv, you have to change the input on the tv and then change the input on the receiver.
posted by jillithd at 1:48 PM on March 11, 2011

Another thought: on our system, the A/V receiver switches input sources very loudly. One the TV, the switching is quieter, but there is also an extra one second delay as the inputs are switches. Each is annoying, but the end result is the same. FWIW, we chose speedier switching over quieter switching.
posted by mosk at 1:51 PM on March 11, 2011 [1 favorite]

Gah, too many typos...:(
posted by mosk at 1:52 PM on March 11, 2011

Switching sources using A/V receiver causes a loud and noticeable click that sounds like a relay being thrown.
posted by fixedgear at 1:53 PM on March 11, 2011

Or I can connect monitor to receiver, then connect the three sources to the TV

Are the monitor and the tv the same thing there? Or two different things?

More broadly:

ISTR that when tvs have an hdmi out, it doesn't always send the full signal. So if you run your bluray to the tv and then connect your tv's hdmi-out to the receiver, you might be getting only DD5.1 instead of one of the advanced audio codecs. Your tv owner's manual should tell you whether it passes the full hdmi stream it's receiving on to the receiver or only some subset.

If you connect everything to the receiver and then the receiver to the tv, that's not the case. The receiver talks directly to the output device and gets whatever the best sound option is.
posted by ROU_Xenophobe at 2:22 PM on March 11, 2011 [1 favorite]

All on/all off (via CEC over HDMI) is very, very dicey at this point in development. If it doesn't work it's probably the manufacturers of your devices who did something wrong, not you. If you haven't yet you can dig through all the setup menus and make sure "HDMI control" or "CEC" or whatever cockamamie name the particular vendor has chosen to use is turned on, but to be honest you're probably better off turning it off for everything and using a universal remote the old-fashioned way, unless your components are all from the same vintage and manufacturer.

In terms of video quality, you will not see in reduction by going through the receiver first. HDMI is digital right up until the display device decrypts it, and bits are bits. That said, HDMI can be finicky about handshaking, especially with older receivers, and you'll probably have better compatability by going straight to the TV (although if your receiver doesn't get the HDMI stream you will miss out on the newer high-bitrate surround formats that only available over HDMI.)

It's also worth noting that control becomes more complex if you have to change inputs on two devices (the TV and the receiver) instead of just leaving the TV on one input all the time and turning it on and off, so that's another reason to go through the receiver if it can successfully pass video to the TV.
posted by contraption at 2:37 PM on March 11, 2011 [1 favorite]

any reduction
posted by contraption at 2:38 PM on March 11, 2011

Seconding (or thirding) that their won't be any signal degradation, but you will be able to still listen without the TV being on. I find that particularly useful when listening to the music channels through the cable box, because that way you can shut the tv off.

I also really enjoy that audible click for some reason. I'm not sure why, I always have.
posted by mhp at 3:50 PM on March 11, 2011 [1 favorite]

For normal runs of cable (6--12 ft), I think the advice you have received is good. However, it is important to note that digital does not imply lossless transmission. Errors do occur - especially over long links, high video bandwidth (3d transmission for example) or with substandard cables. How these bit errors impact the image depends on lots of factors - most you won't see at all, others you will see as block artifacts.

It is possible the pre-amp in your receiver could be better than the pre-amp in your TV which might give you a preferred configuration - but this is not typically an issue for most people...
posted by NoDef at 4:09 PM on March 11, 2011

TV=monitor, sorry for any confusion.
posted by fixedgear at 4:11 PM on March 11, 2011

While it's technically true that dropped packets can lead to signal degradation of the displayed image, it's very different from the sort of degradation you see with component video or other analog sources. In the latter case there will always be a measureable drop in signal quality each time you increase the length of the cabling or add intermediate switching or other links in the chain connecting the source to the display. It's an expected and unavoidable consequence of transmitting an analog signal from one place to another. In the case of HDMI, artifacts tend to be glaringly obvious (blanking, bright horizontal lines across the screen) and exceedingly rare, and should be taken as a sign of a bad cable rather than an incorrect hookup.

I set up HDMI-based video switching systems as part of my job, and 98 times out of a hundred the image will either be perfect or it will not be displayed at all, since the HDCP handshake is usually the part that goes awry. Artifacts are an extreme edge case, and in my experience they invariably disappear when the faulty cable is identified and replaced.
posted by contraption at 6:03 PM on March 11, 2011

ISTR that when tvs have an hdmi out, it doesn't always send the full signal.

Yeah, it bears repeating. If you have decent speakers, care about audio, and if your receiver supports the HD audio codecs (DTS-HD Master and Dolby TrueHD) then you'll probably want to at least connect the Blu-ray player directly to the receiver. Most TVs won't pass HD audio back to to the receiver.

I think the HD audio codecs are the best things about Blu-ray. DVD picture quality is good enough for me. YMMV.
posted by sockpup at 6:39 PM on March 11, 2011

Yeah, to be explicit, going through the receiver is the better way to do it unless there is a problem with your particular receiver that keeps the video from displaying on the TV when you go that way, as is the case for many (even very expensive) early HDMI devices.
posted by contraption at 7:21 PM on March 11, 2011