Firewire Audio IEC61883-6 aka mLAN/A&M Protocol

[Clemfm]

I have a device which requires the SPDIF protocol (IEC60958) over Firewire standard IEC61883-6 and I can verify that OS X CoreAudio does not support this.

Firewire Audio, and specifically IEC 61883-6 (otherwise known as Yamaha mLAN or Audio and Music Transmission Protocol or A/M Protocol) is on the verge of extinction. Yamaha dropped support in about 2008 whilst other vendors appear to have also moved on.

Apple CoreAudio is not as universal as Apple would have us believe. 61883-6 products have had issues with the various versions of OS X whilst many of these products use the more standard (as opposed to SPDIF over firewire) RAW data format.

Does anyone know of:

1. A way to replace CoreAudio with FFADO etc?

2. A tool which allows CoreAudio to be 'tweaked'?

3. A driver for any other device which may support SPDIF over 61883-6?

Clem

[Clemfm]

Judging from the overwhelming response to my post, I gather that Firewire audio has gone the way of the Dodo as far as board members are concerned?

[gdoubleyou]

Not quite, I'm using a UA Apollo Duo via FW800, mLan died a LONG time ago.

[G]

Which device do you have and what are you actually trying to do?

Indeed, I'm still rocking a Firewire MOTU 828mk3. It has always worked perfectly, and does more than just simple IEC 61883-6 audio, which is probably why MOTU has their own drivers for it and keeps them maintained.

The last time I read about mLAN, we were still complaining about switching from ADB to USB, and from PPC to Intel. Yamaha was providing the only impetus and at least half of the code for it on OS X. Yamaha is also notorious for dropping anything and everything for unknown reasons. No one else ever really jumped onboard with mLAN (or have since jumped off), so it wouldn't surprise me if Apple stopped diverting resources towards it years ago.

However.. Was Yamaha solely responsible for S/PDIF audio over Firewire?

[Clemfm]

I'm trying to connect a Sony Lissa amplifier, it is recognized by OS X, however CoreAudio appears to expect only RAW streams and not streams formatted to the SPDIF protocol.

The name mLAN, and A/M protocol etc, have faded, however they were simply alternative names for IEC61873-6.

I can't believe there are no generic drivers or hacks for AppleCoreAudio.

SPDIF over Firewire does appear to have originated with Yamaha, however I have not been bake to find mention of any device using this combination, other than some Sony equipment, which is not surprising given their bias toward the protocol, after all, the 'S' in SPDIF stands for Sony.

[G]

Yes, and the 'P' stands for Philips, but that will be even less useful.

Are you sure about IEC61873-6? From what I can see today, that's simply audio over Firewire, which leads me to believe it's native (aka class) audio. mLAN and other proprietary protocols (it was never a native standard) might have used it, but there's nothing in the code of IEC61873-6 that mentions mLAN specifically. And from what I remember, mLAN was capable of more than just audio--It was also a kind of networking system for multiple devices. Anyway, if the Lissa is indeed using mLAN, you will likely need specific drivers from either Sony or Yamaha, as the functions should not be expected in CoreAudio natively.

The most recent work on mLAN that I recall was a Universal Binary (Intel) update from Yamaha many years ago. Just to get that out of the way, have you installed that?

[Clemfm]

IEC81663-6 is 'simply' Firewire audio and is thus supported, and actually a major part of, Apple CoreAudio, however the IEC standard did not define exactly what formats the streams could be. Raw data is the most common, however other formats are possible such as SPDIF. Apple chose not to support SPDIF over IEC81663-6.

The name escapes me now, however as some vendors began to ship Firewire audio products using parts of IEC81663-6 which were not precisely defined in the standard, Apple created a KEXT/API which allowed vendors to 'patch' IEC81663-6 as required.

IEC81663-6, from my research thus far, was originally mLAN. Yamaha present mLAN to the IEC and it was ratified as the IEC81663-6 standard (I'm open to other opinions on this).

mLAN becomes a 'networking system' when combined with the AV/C control protocol. There is an AVCBrowser included with XCODE which people are using to control set top boxes equipped with a Firewire connection and indeed they are able to also use VLC to recored an MPEG HD stream from the box, but I digress.

Sony did release (eventually) a Lissa driver for Windows XP, I believe this 'simply' added SPDIF over Firewire support to Windows Firewire 81663-6 drivers.

I've tried a few Yamaha drivers, however I'm yet to find one that will even install in 10.8.5, I'll take another look whilst I'm also going to try some Steinberg drivers as it appears that they have partnered with Yamaha on Firewire drivers, to at least some extent.

[Clemfm]

I've spent some more time on this and can now confirm the information in my earlier posts.

I also read about a tool in the AppleFWAudio SDK called IsocViewer. It scans the Firewire bus for any isochronous (audio) streams.... and it can see my Sony Lissa amplifier/receiver.

OS X System Information and the SDK's AVCBrowser could also see the Lissa, however IsocViewer can see the actual 44.1KHz SPDIF (IEC60958) over Firewire 81663-6/A&M Protocol/mLAN stream

Screen Shot 2015-01-03 at 10.59.02 PM.png

FDF= Sample Rate hex op code
FMT = Stream formatting, 0x01 = an audio stream

I've done further research and it appears that I'm going to have to delve into XCode to access the stream, although this post is encouraging:

"The nice thing is that, on a Mac running OS-X, it can all be done in user space without any kernel programming required. There are nice user-clients provided for interfacing with the IOFireWireFamily, and the IOFireWireAVC kexts in user-space, even for handling isochronous streams without writing any kernel-level code. Check out the FireWire SDK (http://developer.apple.com/sdk/#FireWireX.) for details on using these user-mode interfaces."
http://lists.apple.com/archives/firewir ... 00043.html

[Clemfm]

If anyone has any other 'legacy' Firewire audio interfaces (those that wont work beyond OS X 10.6,10.7,10.8 etc) , I would be interested in seeing what IsocViewer tells us when they are connected. I am certain at least some of them probably also used SPDIF over Firewire, however I'm yet to verify this. However, if IsocViewer can see the stream, then it can be read...with the right code etc, unless it is of a totally proprietary, non-standard format.