Firewire's untapped potential  

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.

They are doing it for HDTV recording atm

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

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

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

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

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

I don't get this. Creative Audigy 2 ZS supports DVD-Audio. So, in theory some hacker might access the decoded audio stream. :confused:

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

i've just sent amirm of microsoft a pm. will report back if he responds to me.

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.

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.
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

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?

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).

Justin

You can already control many receivers, so that part has long been available, just not via Firewire.

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.).

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.

Ron

Not a custom app, but a control and automation system that can control them all. Put the control and coordination at that level.