hdmi switching vs. pass through

Discussion in 'Amps, Pre-Pros & Receivers' started by enoch, Jan 30, 2008.

  1. enoch Audioholic Intern

    enoch
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    Im looking to get a reciever and was wanting to know what the difference between those two are and whats better? Im hooking up a blu ray, hd dvd, cable dvr box to the receiver all via HDMI and then hdmi from the reciever to the tv. So which one do i need to get...hdmi switching or pass through?

    Enoch
  2. TLS Guy Audioholic Overlord

    TLS Guy
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    Don't get pass through or a lot of things won't work because of the repeater architecture of the HDCP codes.

    I would get HDMI 1.3, the latest standard, and since you want Blue Ray, get a receiver that will decode Dolby True HD.
  3. enoch Audioholic Intern

    enoch
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    So whats the difference between HDMI pass through and HDMI switching on a av reciever?

    Enoch
  4. Zetram Audioholic Intern

    Zetram
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    I believe that w/ passthrough the hdmi signal from your devices isn't touched by the receiver. While switching it actually tries to emulate the signal.
  5. no. 5 Audioholic Field Marshall

    no. 5
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    This is the way I've always heard it:

    HDMI switching does not use the audio stream

    HDMI repeating does.
  6. enoch Audioholic Intern

    enoch
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    So i need to get a reciever that has HDMI pass-through? right?

    Enoch
  7. TLS Guy Audioholic Overlord

    TLS Guy
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    We have had this issue a lot. Please put HDMI in the search and look at some of the threads. I did explain this in my first reply.

    HDMI started out as intended as a good digital interface. Then what I call the unsatisfactory people who inhabit Hollywood wanted DRM. So Digital Rights Management Corp LLP came into being. Six digital keys were introduced and there had to be a handshake between the sending and receiving unit. These are the HDCP codes which have to be in compliance.

    Then switchers and receivers with HDMI inputs were created, and Hollywood became paranoid that the output ports would be a haven for pirates. Repeater architecture was the result. Now a TV is an end device and one wobbly handshake is enough. So you can connect a cable box, satellite receiver DVD etc to a TV with one certification. However if you connect those devices to a receiver or any other device that outputs HDMI, there has to be constantly repeated wobbly handshakes of the digital keys between the sending device and the receiver, otherwise no output to the TV.

    Now pass through is just that. No repeated handshakes of the HDCP codes.
    A switcher of recent vintage should have HDCP compliance with repeater architecture.

    So what you actually need is HDMI switching with repeater architecture.
    Now there are no comments for version 9 of the HDCP codes. That makes eight already not including errata. The latest version is HDMI 1.3 which will pass the lossless audio codecs of HD formats such as Blue Ray. If it has HDMI 1.3 the receiver should also be able to decode the new lossless audio codec Dolby True HD.

    Now if think you might escape this nightmare by using component video outputs, think again. The Hollywood crowd have now taken care of that by insisting that devices that output HD downgrade the quality to 480i at the analog outputs including component video. Bottom line you can only enjoy HD from HDCP compliant HDMI inputs and outputs.

    If you this is heavy handed, so do I.
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  8. Seth=L Audioholic Overlord

    Seth=L
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    TLS Guy, you aren't answering his question.

    The correct answer to the question is this. HDMI pass-thru and HDMI switching are the same thing.;)

    Less expensive receivers have HDMI pass-thru, or switching only. What this means is the HDMI ports are used just like any other video switcher, it takes video inputs, and has an output to a display. That is all they do.

    HDMI repeating is a step up from HDMI pass-thru/switching. It still does the switching, but adds the ability to take the audio bitstream from the HDMI source. Such sources include satallite/cable box, upscaling DVD player, Blu-ray player, HD DVD player, PS3, or an X-box 360 (the newer that features HDMI output). Some of those receivers also have scalers, but I wouldn't get to excited about those.
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  9. TLS Guy Audioholic Overlord

    TLS Guy
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    I probably am guilty of not making it completely clear. However I did say he needs switching with repeater architecture. For example my Direct TV Tivo HD DVR was installed just under two years ago. It passed HDMI through my Gefen switcher fine. In October Direct TV had to change it out for a newer model to handle their new 5 LLB system. The new HDDVR has repeater architecture and will not pass through the Gefen switcher, as it is a vintage prior to repeater architecture.

    So the big point is he needs a fully HDCP compliant unit with repeater architecture. If he buys an older unit at a discount price that does not have these features he will have grief with a new Blue Ray player and any other device that requires repeated handshakes when connected to a device that outputs HDMI.
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  10. Seth=L Audioholic Overlord

    Seth=L
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    For the record, I am not saying you where incorrect.

    What you where saying was right, but I am sure it went above his head. You have to assume the OP didn't know what repeating even was considering he didn't know that switching and pass-thru where the same thing.;)
  11. enoch Audioholic Intern

    enoch
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    hey :( atleast im trying to learn before i speak and try to sound like i not what im talking about. But i really appericate the help his statement did go alittle over my head but once i do even more research i will totally understand what he is saying. Thanks for the help.

    Enoch
  12. Seth=L Audioholic Overlord

    Seth=L
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    You do understand now that HDMI switching and pass-thru are the same though right?

    Let me show you a receiver that does pass thru/switching only.

    Onkyo TX-SR505. http://www.us.onkyo.com/model.cfm?m=TX-SR505&class=Receiver&p=i

    It will only allow you to connect them much like any other video format, just for switching purposes.

    This is a receiver with a repeater.

    Onkyo TX-SR605 http://www.us.onkyo.com/model.cfm?m=TX-SR605&class=Receiver&p=i

    Think of it this way. Before when you had a DVD player connected to a receiver you needed a digital audio cable and the video cable for it to work all at once. With HDMI, you don't need to. HDMI carries the video and audio signals in one cable at the same time. The receiver will take in the DVD's output and will extract the audio from the HDMI cable and process it for surround sound. It then sends the full signal to the display (both audio and video)

    The true advantage of the repeating feature is when you have an HD DVD or Blu-ray player that has the next generation of surround sound formats on them. Older receivers can't decode these formats, but the receivers with HDMI repeating can utilize them in one way or another.

    A few of these receivers can't decode the bitstreams of the new formats, but can decode lossless PCM over HDMI. Most of the HD DVD and Blu-ray players can decode the bitstreams inside the player (for the HD DVD and Blu-ray formats) and that converts the audio to high resolution lossless multichannel PCM. The audio is still digital and needs to be converted to analog inside the receiver, and HDMI is the only data transfer cable type that can accept that kind of input. If the receiver was pass-thru or switching only, the HDMI would "pass-thru" the receiver and the audio would not be derived from the HDMI source.

    Feel free to ask any questions you might have, and I will gladly clear anything up that is not understood. I know it's hard to soak in all at once, so don't be afraid to ask.:)
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  13. TLS Guy Audioholic Overlord

    TLS Guy
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    Well, I think we got it clear between the two of us. Sometimes when you post it seems clear to the author. Glad of your feedback.
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  14. Seth=L Audioholic Overlord

    Seth=L
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    We are all here to learn some way or another.:)
  15. xboxman2 Audiophyte

    xboxman2
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    hdmi and optical cable

    i was reading this post and i have a question. if i have an hdmi receiver without repeater architecture it will only pass the video and not the digital audio to the receiver rigth? but then if i put a optical audio cable will it work?
    for example let say i have a 360 conectec to the pass through receiver through hdmi but also optical audio will that work or in order to get the true sorround i have to have the repeater architecture in the receiver?
    thanks in advance
  16. Seth=L Audioholic Overlord

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    If you have the HDMI connected to the receiver, then passed on to the TV (logically I will assume this is the case) then you should connect an optical cable from the xbox to the receiver to the related input with the HDMI. What receiver do you have?
  17. JK_Livin22 Audioholic Intern

    JK_Livin22
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    Hi guys, I am somewhat new to the world of hi-fi audio/video and am inferring that enoch is too. Perhaps I have a better understanding of his perspective as much or your comments have been helpful to me, but perhaps may be much more in depth than what he was looking.

    HDMI pass through has already been explained, it simply passes the video signal from your source component (Blu-ray player, CD player, cable box, etc.) through an HDMI cable that connects the source component to the receiver and then from the receiver through a second HDMI cable that connects the receiver to the television. The video signal is not processed but merely passed through the receiver to the television. With HDMI 1.3 it will also carry the audio signal because of the repeater architecture. But with HDMI 1.1 you will also have to connect a digital coax or digital optical cable to carry the audio from the source components to the receiver. (I'm not sure about HDMI 1.2)

    HDMI switching simply allows the receiver to switch which source component it is sending to the television through the HDMI cable that connects the receiver to the television. Depending on what you have your receiver set to, it will switch between the Blu-ray player, the CD Player, cable box, etc. To the best of my understanding, this is what is meant by switching. If the specs for a receiver say that it has HDMI switching, it is basically just stating that it has multiple HDMI inputs (usually a bare minimum of 3, most likely 4 or more on newer models) to accommodate several source components and at least one HDMI output for connecting the receiver to your television or video projector.

    This is the first question I have ever tried to answer, so I am hoping that what I have said is both helpful and accurate. Seth=L and TLS guy, perhaps you guys can check out what I have said here to make sure I have not provided any inaccurate information. Thanks.
    Last edited: Feb 2, 2008
  18. TLS Guy Audioholic Overlord

    TLS Guy
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    Don't forget HDMI is two way! There is a communication port. Anything outputting an HD signal will require full HDCP compliance with REPEATER architecture. Otherwise no output from the receiver. This is the part that causes the grief, and the question no picture, just error signal, PLEASE HELP.
  19. Seth=L Audioholic Overlord

    Seth=L
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    You admitted you are pretty new to audio, so you won't be surprised to find you are a bit off on a few things.;)

    HDMI 1.3 is a specification for the interface capability. HDMI 1.1 can carry multichannel LPCM, HDMI 1.2 can carry multichannel LPCM as well as DSD streams (sacd), and HDMI 1.3 can carry multichannel LPCM, DSD streams, and the new surround format bitstreams (Dolby Digital Plus, TrueHD, and DTS-HD). HDMI 1.3 can also support deep color on the video side.

    The Onkyo TX-SR505 I linked above has HDMI 1.3, but it does not process audio for example. At the same time the TX-SR605, also has HDMI 1.3, can process audio.

    Then as described before there is the repeating feature, which allows a receiver to decode information off of the HDMI transmission, but is limited to the HDMI spec it uses (1.1, 1.2, 1.3).
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  20. JK_Livin22 Audioholic Intern

    JK_Livin22
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    I am currently using a Marantz SR4001 with HDMI v1.1. It seems that the only disadvantage is that I also have to connect a digital coax for the audio, no big deal to me. Are you saying that if I replaced the SR4001 with a receiver that had HDMI 1.3, then the new receiver would have problems sending the video signal from the source components to the television? If my understanding of what you are sayings is correct (and I don't think that it is) then either source components or source material (the actual Blu-ray disc) that were created prior to HDMI 1.3 will not be in compliance with HDCP / repeater architecture and therefore will not play on receivers that have HDMI 1.3 with repeater architecture? That doesn't make sense. The cable companies aren't going to supply all new HD cable boxes to everyone who has purchased an AV receiver with HDMI 1.3. Nor would consumer go out an repurchased Blu-ray players or discs that met the new HDCP protocol. Where is the problem by the way, with the hardware or source material? There is something that I am not understanding correctly; I am confused...
    Last edited: Feb 2, 2008

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