Firewire's untapped potential - AVS Forum
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post #1 of 26 Old 03-15-2004, 05:03 PM - Thread Starter
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I was wondering if anyone had any knowledge of any movement within the CE and PC industries to advance Firewire as the replacement for SPDI/F. Aside from the increased bandwidth afforded by this standard, it could also allow for a smarter connection between audio devices.

Consider this:

I make a Firewire connection between my PC and my receiver. My PC has a standard driver for a "Firewire Audio Device". The PC is able to query the receiver to determine the types of audio streams it is able to handle (eg. 8 steams of 24-bit PCM audio @ 192 kHz, Dolby Digital, DTS, WMA, etc.) and then the driver will present these capabilities to the OS just as if it were a PC sound card. It really should be that simple. And the same protocol could allow for connecting consumer audio gear to a receiver, also.

I am sure I am not the first to think of this. But is anyone actually doing it?
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post #2 of 26 Old 03-15-2004, 05:38 PM
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It would make it too easy to pirate stuff. IE too easy to get sued by the MPAA and RIAA.

CE were talking about moving everything to firewire back in 2000, that talk just faded away.
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post #3 of 26 Old 03-15-2004, 07:12 PM
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post #4 of 26 Old 03-15-2004, 08:36 PM - Thread Starter
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@Versa - Copy protection would have to be implemented. This is more important for the CE stuff ATM. As far as the PC goes, if you are sending a digital stream from a PC, then it's not the bits going out of the PC that the content providers would be worried about. It would be how the bits got in the PC in the first place. :p

Firewire would address the problem people currently have with sending 6 channels out of a PC to a HT setup. Your only choices are to go analog, or use something like the NForce(2)'s APU to encode to Dolby Digital and send out the SPDI/F.
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post #5 of 26 Old 03-15-2004, 09:30 PM
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You guys are out of the loop. 1394 audio has been around since October of 2002
with the introduction of the Pioneer VSX-49TXi receiver and DV-47Ai DVD
and SACD/DVD-A player. The interface is encrypted and is the only
interface that SACD is allowed to be passed over.

See this wicked long thread for all the details:

http://www.avsforum.com/avs-vb/showt...hreadid=201258

Ron

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post #6 of 26 Old 03-16-2004, 02:39 AM
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1st post so be nice!

dr1394 does this mean that a PC can be connected to a suitable firewire equipped receiver (such as the Pioneer VSX-49TXi), and that it will appear as a multi-channel sounds card to windows (as mrcorbo asked originally)? Or does encryption prevent this, even wrt to non-encrpyted material eg games, cd audio, general windows sound schemes? I have read the thread you mentioned and it refers (correct me if im wrong) to use of 1394 as a digital interface between CE devices rather than between a PC and a receiver. Is this possible, and can it be enabled via software?

Thanks in advance

alistair
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post #7 of 26 Old 03-16-2004, 03:08 AM
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It's not an encryption issue. In fact, regular CD 44.1/16 bitstreams are sent
unencrypted even on the CE gear. The problem is nobody (including M$) has
bothered to develop a 1394 audio driver for the PC. If you plug a Pioneer
VSX-49TXi into a PC, the PC will recognize it no problemo and then ask you
for a driver (that does not exist).

Someone needs to write a 1394 audio driver for the PC (most likely Windows XP,
which has the most advanced 1394 capabilities). Although it couldn't do SACD
or DVD-A, it would work with CD, DD and DTS. Of course, writing a Windows
driver requires uber knowledge so there's probably only a few people out
there that could even attempt such a thing. I'm an embedded systems guy, so
it's way over my head (I can just barely use Windows, nevermind program
for it).

Ron

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post #8 of 26 Old 03-16-2004, 03:31 AM
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I see. So would it be best to actually petition the manufacturers to create windows drivers specifically for each device (or create generic drivers for whole classes of devices), or is this really down to Microsoft to create a reference driver that all manufacturers could support? Also, i notice in your post that DVD-A could not be supported. Is this due to encryption? From what i understand, dvd audio disks can be read by standard pc dvd-rom drives. However, to access the hi-rez mlp encoded audio, use of the 5c encryption protocol is necessary. Is this another software issue, ie are their no software dvd-a players that support this method to permit digital output over 1394. The holy grail would be to use one digital connection between the pc and receiver to carry encrypted/unencrypted multichanel audio in many different formats. Barring any licensing issues, is this possible, provided someone was willing to fork-out for the licensing?

thanks again

alistair
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post #9 of 26 Old 03-16-2004, 04:46 AM
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DVD-A on the PC is an encryption problem. There are no 5C enabled 1394 cards
for PC's. The reason for this is that a 5C enabled PC card can't satisfy the
robustness rules of 5C which state that the in the clear bitstream is not
easily accessible. Since the in the clear DVD-A bitstream would be right
on the PCI bus, it's a definite no-no.

The only way to do this (and be able to sell it) would be to have a card that
does everything. That is, the DVD-ROM drive would have to directly plug in
to the card and the CPPM decryption (the encryption used on DVD-A) and 5C
encryption would have to be done on the card (preferably inside one chip
so that the in the clear bitstream never sees the light of day). At this
point, you have almost a whole stand-alone DVD-A player on a card, so it's
not very cost effective.

As for a PC 1394 audio driver, a generic driver would be adequate. It would
be an A&M (Audio and Music) or IEC 61883-6 protocol driver (which is what
all the 1394 receivers use).

Ron

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post #10 of 26 Old 03-16-2004, 05:33 AM
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I don't get this. Creative Audigy 2 ZS supports DVD-Audio. So, in theory some hacker might access the decoded audio stream. :confused:
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post #11 of 26 Old 03-16-2004, 07:52 AM
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dr1394: thank you for the explanation. i had no idead that the robustness criteria were so stringent. Unfortunately your response has also raised two further questions:-) Firstly, is it necessary for the dvd audio stream to be partially decoded before it is sent to the receiver via firewire? Otherwise would it not be possible to read the encrypted data off the dvd and send it directly to the firwire port without the data ever being in the clear? Secondly, if decoding is to be done on the pc, can this decoding be done on a pc sound card provided that the data is sent to the card in the 5c format, and that once the decoding to high-rez pcm audio has taken place, the information is then encoded into the 1394 serial stream on chip, thereby never exposing the unencrypted information?
Sorry, i think that was more than two questions, but i would really appreciate any input.

jfma: i think (in light of what dr1394 has said) that the encrypted audio stream is read off the disk and then sent to the sound chip where it is decoded and converted to an analog signal on chip. At no stage is the decoded, high-rez unencrypted signal ever exposed, thereby preventing any access to the information. the only output is in the analog domain and the content producers seem less concerned about copying this degraded material
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post #12 of 26 Old 03-16-2004, 08:01 AM
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i've just sent amirm of microsoft a pm. will report back if he responds to me.
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post #13 of 26 Old 03-16-2004, 11:13 AM - Thread Starter
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@ dr1394 - Thanks for the responses. I was aware that some receivers and players were already using 1394, but was under the impression that they were proprietary (i.e. Pioneer receiver only connects to Pioneer DVD-A player). Is this still the case?

Further, besides a driver on the PC side, I think there needs to be some kind of standard protocol for the receiving audio device to transmit its capabilities to the transmitting device, so that if a receiver supports WMA decoding, for example, the PC (or other audio source) knows that it can just send the WMA bitstream unaltered. Otherwise, the sending device would know that it had to send multiple PCM streams, instead.

@honeyjigga - Good idea about the PM. Hopefully we get a response from him or someone else from MS.
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post #14 of 26 Old 03-16-2004, 11:20 AM - Thread Starter
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Quote:
Originally posted by jfma
I don't get this. Creative Audigy 2 ZS supports DVD-Audio. So, in theory some hacker might access the decoded audio stream. :confused:
The Audigy does all of the audio processing onboard the card. There is never any decoded data going over the PCI bus. The fact that the Audigy can't support a 5C certified 1394 port is why it will only output DVD-A data via the analog outputs or downsampled and sent over SPDI/F. You will likely never be able to output full fidelity DVD-A digitally from this card.
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post #15 of 26 Old 03-16-2004, 11:25 AM - Thread Starter
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While a generic driver is necessary and would certainly fulfill all of the important functions, imagine if a manufacturer came out with a custom driver that allowed you to set up your receiver from a GUI on your PC!

How about clicking a button to download a new firmware for your receiver that updates it to decode the latest Dolby surround technology?

Once you have this digital connection, it opens up all kinds of possibilities.
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post #16 of 26 Old 03-16-2004, 11:55 AM
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Imagine now *having* to start downloading bug fixes and patches for your receiver because its so easy to update the BIOS so they decided to release it early in a buggy condition to meet the marketing milestone.

Imagine now *having* to connect your receiver to your PC becuase they decided to save 30 cents and remove the functionality from the remote and front panel.
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post #17 of 26 Old 03-16-2004, 02:20 PM - Thread Starter
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@ kromkamp - Not very likely. CE appliances are held to a much higher standard than PC peripherals are and any CE company knows that if you develop a reputation for buggy products it will hurt you more than would be gained by being able to hit a release window.

The second scenario is even more unlikely. Look at all of the threads dealing with people wanting to use their remote controls to control their PC's. I have Girder set up on my PC to control Zoom Player and MyHD even though I have a wireless keyboard and mouse. So I doubt that consumers would ever buy a receiver that *required* a PC connection in order to fully function. I like the concept of being able to set up my receiver via a WIMP interface, because the more features available the harder it is to navigate the various set-up menus with a remote.
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post #18 of 26 Old 03-16-2004, 03:46 PM
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Quote:
Firstly, is it necessary for the dvd audio stream to be partially decoded
before it is sent to the receiver via firewire?
Yes, it's actually decoded all the way to PCM. This avoids having an MLP
decoder on the receiver and saves on licensing costs. The important point
to realize is that 5C encryption only exists on the 1394 link between devices.
The bitstream input to a 5C enabled 1394 link layer controller (LLC) is always
in the clear. Same thing for SACD, the DST is decoded and only DSD is sent
on 1394.
Quote:
Thanks for the responses. I was aware that some receivers and players
were already using 1394, but was under the impression that they were proprietary
(i.e. Pioneer receiver only connects to Pioneer DVD-A player). Is this still
the case?
Although there is some early high-end 1394 equipment that is proprietary (the
dCS stack is a good example), all the current stuff follows open protocols
established by the 1394 Trade Organization (http://1394ta.com). It has been
verified that the Sony XA-9000ES 1394 SACD player works with the Pioneer
receivers and the Pioneer players work with the Yamaha RX-Z9 receiver.

Ron

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post #19 of 26 Old 03-16-2004, 04:53 PM
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Quote:
While a generic driver is necessary and would certainly fulfill all of the important functions, imagine if a manufacturer came out with a custom driver that allowed you to set up your receiver from a GUI on your PC!
That functionality wouldn't be in a driver, it would be in software running on the PC and talking through the driver. The driver only provides the conduit via which software can talk to the device via the Firewire bus. You don't want to make every device have it's own driver, you want to have a generic driver and have software that uses that generic driver to talk to devices that it understands.

This type of architecture is already there in control and automation software products (like my own), but so few products use Firewire that not many of us have gotten into supporting them. Does anyone know if any of the vendors who have put Firewire on their receivers actually provide documentation of the protocol?

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post #20 of 26 Old 03-16-2004, 06:57 PM
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I have been saying this for so long.

How sweet would it be if you plugged a receiver in through firewire and it became a 7.1 sound card in windows with the software volume controlling the receiver volume! And anything else on the receiver.

Maybe then we could stop squabbling over whether or not to use WMA instead of DD on new HD material because the digital interface to our audio equipment would be decoupled from a compression scheme.

Heck you could even plug a second receiver in for another zone.

You can get unamplified solutions now that do these things. They are pro grade digital recording interfaces like the ones from: http://www.motu.com . I have seen these in action and I am considering one myself with some separate amps to drive the speakers. They just plug in, have WDM and ASIO drivers and just work as a 8 channel in/out sound card. You can even stack 4 of these on firewire bus for 32 96/24 channels in/out! There not even that expensive and can be found on Ebay.

I cant believe there hasn't been more progress in this area, spdif needs to be replaced bad, and firewire is the perfect fit for audio (DVI having the same advantage over firewire in the video side of things).

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post #21 of 26 Old 03-16-2004, 09:11 PM
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You can already control many receivers, so that part has long been available, just not via Firewire.

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post #22 of 26 Old 03-16-2004, 09:38 PM - Thread Starter
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@ dr1394 - Looks like I haven't been paying enough attention. You can actually get one of the Pioneer Elite models (VSX-55TXi) with i-Link for under $1000. Now show me a DVD-A & SACD compatible mega-changer with 1394 output and we'll be in business. :D

@ Dean - Your right, of course. This would be more of a custom control panel that would interface with the driver itself. People do tend to use the term "driver" inclusively, though, to refer to the support software as well. I do realize that it's not technically correct, though.
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post #23 of 26 Old 03-17-2004, 08:38 PM
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Right, but my point was the control over firewire is icing on the cake, its the cake I want which is raw uncompressed 96/24 multichannel audio over a digital interface from my pc which for some reason seems to be hard to find.

Also IR/rs232 reciever control software as far I know is not going to expose the recievers volume and routing controls to the directx/win32 api's as a sound card driver would, so yes you get computer control through the one custom app, you do not get it through anyone else app that understands sound card control(such as media center, dscaler, etc.).

Quote:
Originally posted by Dean Roddey
You can already control many receivers, so that part has long been available, just not via Firewire.
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post #24 of 26 Old 03-18-2004, 12:36 AM
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On the Pioneer VSX-55TXi 1394 receiver, the control is in the other direction.
That is, the receiver controls the player over 1394 so that one remote can
control both the receiver and player.

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post #25 of 26 Old 03-18-2004, 02:07 PM - Thread Starter
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@ dr1394 - How much of the functionality that I referred to in my first post is actually available now, with the present protocols, as implemented in currently available receivers?

Specifically WRT the ability on the PC side to query a device for its capabilities to determine what types of audio streams it can accept via 1394.

Is it just a matter of Microsoft or a 3rd party writing a proper driver for the PC side?
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post #26 of 26 Old 03-18-2004, 02:23 PM
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Quote:
Also IR/rs232 reciever control software as far I know is not going to expose the recievers volume and routing controls to the directx/win32 api's as a sound card driver would, so yes you get computer control through the one custom app, you do not get it through anyone else app that understands sound card control(such as media center, dscaler, etc.).
Not a custom app, but a control and automation system that can control them all. Put the control and coordination at that level.

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