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Digital links

Discussion in 'AV Receivers & Amplifiers' started by paiger, Aug 8, 2002.

  1. paiger

    paiger
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    Anyone got any thoughts on the singal digital link issues? As far as I am aware, optical and coax are not up to DVD-A, SACD etc so we need something better. DVD-A seems to be possible through links such as Tags and Denons but SACD has yet to be licenced. I understand that Sony will push for Firewire which looks set to become an industry standard for digital data transmition. This is nice cuz it has other benefits too like control options.

    However, I read a bit by a guy at Tag who said they did not feel Firewire was good enough for the job and hence would not support SACD.

    Anyone got an insights on this? I am holding of buying high end gear until this gets sorted out. I want something like a Tag or Arcam processor and a one box CD/DVD/DVD-A/SACD solution. At present the Tag DVD32 has everything but SACD and it looks like it may not get it.

    I'm not spending £4000 on a DVD player and then finding that SACD lives and DVD-A dies and no digital link is available for my equipment.

    Comments from informed and techie types please.

    S
     
  2. Reiner

    Reiner
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    Grmbl, just finished my reply when the internet connection broke ... :mad:

    Well, here we go again:

    There are quite a few contenders for digital links, like SDSI, FireWire aka IEEE1394, DVI and the proprietery links like Denon and Tag.


    FireWire is limited to around 400Mbps and thus would require a compression to transmit a video signal, i.e. an (MPEG-2) encoder at the source and a decoder at the display - not good me thinks if you consider that the video doesn't always have to come from a DVD player.

    DVI in it's 1.0 flavour supports video only; it's alread available as some Asian DVD players and (Plasma) displays have it.
    As it does not carry audio a new version / standard has been written, called DVI HDMI. This will beat FireWire hands down with around 5000Mbps and can transmit HDTV (1920x1080i) or DVD-A (max. 8 channels @ 96kHz/24bit) without any problem.
    Intel's HDCP (High-bandwidth Digital Content Protection) will probably be the choosen format for copy protection and has been accepted by the MPA (Motion Picture Association) for digital broadcast.
    DVI+HDCP can therefore also used for DVD players (though not in HDTV form yet of course, there we need to wait for Blue-Ray ...).


    Haven't heard much about SDSI lately so I am not sure what's up with that.


    Well, in the end I guess we need to wait and see, but let's hope the (technical) best standard will be choosen and not some proprietery interface.
     
  3. HMHB

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    Firewire is set to become 1394b soon.
    This will start off with speeds of 800 Mbps. I've copied a paragraph from a 1394b article:-

    IEEE 1394b allows extensions to 800Mbit/sec., 1.6Gbit/sec. and 3.2Gbit/sec., all over copper wire. It supports long-distance transfers to 100 meters over a variety of media: CAT-5 unshielded cable at 100Mbit/sec., existing plastic optical fiber at 200Mbits/sec., next-generation plastic optical fiber at 400Mbit/sec. and 50-micron mulitmode glass optical fiber at up to 3.2Gbit/sec. The improved speed and distance capabilities of 1394b result from two major improvements: overlapped arbitration and advanced data encoding
     
  4. russraff

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    I thought that Pioneer's new flagship amp, the imminent replacement for the AX10, and DVD player were to use the Firewire standard? Could be a sign of things to come...

    Russell
     
  5. paiger

    paiger
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    Yes, I think Pioneer are going to be using Firewire. As I understand it, the idea will be to use Firewire as purely an audio link and HMDI (or whatever it is) as video. I have seen the new video plugs and they are tiny compared to scart and allow extreme high quality video transmition.

    I also hope we get the best as a standard but I think it's important that there is an industry standard and I guess Firewire has a good lead. I was just wondering if the Tag guy was right when he said it wasn't up to the job.

    S
     
  6. Reiner

    Reiner
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    I thought that Pioneer's new flagship amp, the imminent replacement for the AX10, and DVD player were to use the Firewire standard? Could be a sign of things to come...

    Yep, I posted that before in the Amplifier and Receiver section, was included in my above post, too, before it went into the internet nirvana ...
    Though I am not sure what Pioneer will use it for - perhaps audio only!?

    Re Tag: as I understand they would like to see DVI-HDMI as the choosen standard.
     
  7. Nic Rhodes

    Nic Rhodes
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  8. paiger

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    Very interesting Nic. So, are you saying that Tag are actually using DVI now? Basically, the problem they have is Sony refusing to license it for SACD? Typical Sony if course, I guess they own the patent on Firewire or something. It's a shame.

    So basically, we are saying that Firewire is fully capable for high res audio but not audio/video? I guess the alternative is two leads again. Pity, if it can be done with one.

    S
     
  9. Nic Rhodes

    Nic Rhodes
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    The Tag PSM board output DVI now. People who are using it speak very highly of it. I have seen it only once and put it at the top of the deinterlacing solution pile.

    DVI is a lovely solution that has real future proof capability now. Firewire can currently send

    compressed video and PCM sound
    compressed video and compressed sound (DD /DTS)
    high quality audio (PCM?)

    It cannot do any high def stuff like I am seeing sunday. It can't do pictures and decent non compressed multi channel audio. Blue ray? Forget it. DVHS HiDef. No way. Scaler to projector / plasma once the signals have been 'expanded'? Forget it. Analogue RGBHV or DVI only apply please.;)

    If anyone has bothered to fire up a PC with a DVI aware plasma / projector and seen the difference we would not even be talking firewire.

    Firewire is along way from this and needs MUCH work. DVI is there now hence Tag, Goldmund etc etc. I just wished I knew more about the DVI plans but the regulatory bodies make it REALLY difficult for non industry bods like to see the stuff. :mad:

    Don't forget if we transfer SACD digitally, non of the current amps / processors / receiver can understand it anyway! They are ALL PCM for PCM stereo or DD / DTS / MPEG. Even if we put a SACD aware chip into 'modular' receivers (Tag / Theta) then the whole output chain needs to be changed unless we convert SACD (and all it noise) to PCM which completely defeats the object of DSD in the first place. Mind you they currently do that for bass management but don't tell anyone anyway!

    The industry is dangerously close to be palmed off with a substandard half solution with firewire. Buyer beware.:D
     
  10. Matt F

    Matt F
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    I agree - especially regarding having an industry standard otherwise if you own, say, a Tag AV32R and an Arcam FMJ23 then you'll be stuffed if Tag and Arcam decide to use different digital transfer methods?

    Matt.
     
  11. John Dawson

    John Dawson
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    Well with a CD23 you would always use an SPDIF output to go to the TAG processor - this is an industry standard :) However since the CD23's digital to analogue conversion is arguably better than that inside just about any processor it would IMO be better to use a processor with a very clean analogue pass through path for the best results from CD using a CD23.

    On the hi res digital link it seems to me that HDMI is the way to go and it is the only way you can carry everything at full resolution on one cable. There are question marks over the link's audio jitter performance however which won't be resolved one way or the other until proper evaluation samples of chipsets appear - probably sometime next year - and it is not IMO a given that such a digital link will necessarily outperform decent D/A conversion inside a DVD player followed by an analogue pass through in the processor. It is also bloody complex to put inside a processor. It will however be very convenient from the user's point of view. And if you haven't guessed it I have read the spec.

    John Dawson (Arcam)
     
  12. paiger

    paiger
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    Hi John, thanks for the reply.

    Do you know if Arcam have any plans to incorporate SACD? All I want is a top-notch player that does it all. I could even put up with seperate DVD/DVD-A and CD/SACD players if I must. The reason I asked about ditial links was that many DVD players are starting to appear that do it all (Pioneer 747 etc) . The problem with 2 boxes is that you need 2 sets of 5.1 cables unless said link exists. I suppose one digi cable from DVD and 5.1 analogues from a CD would be OK but it's a lot of wires.

    Also, just had a quick look at the AVR100 and 200. Do you know if these come in Silver? I'm upgrading my amp soon and these look promising.

    Steve
     
  13. Dubbing Mixer

    Dubbing Mixer
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    Perhaps worth pointing out that the DSD lot allow 384kHz sampling rate PCM to be used in producing for SACD so perhaps that is what we should be looking for in the reproduction chain...
     

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