Sometimes, what you think is obvious does not always turn out to be the case.

So it was when I decided to connect my Tablet PC (an HP Tx2000ed) to my audio amplifier (a Denon AVR-3808). I was driven to this step by the fact that trying to browse through the music libraries stored on my Media Servers while using the interface on the AVR-3808 was an exercise in frustration. The performance is absolutely abysmal.

But then I thought, why don’t I use the GUI of Windows Media Player to browse my music libraries?  I can use my Tablet PC running Windows 7 to browse the libraries (the browsing performance is good), and if I play back the tracks on the Tablet PC, and connect via the digital S/PDIF interface to the AVR-3808, then I will send a high-quality digital audio stream direct to the 3808 amplifier, and have the best possible results.

It seemed like a good idea, so I found a cable that had a 3.5mm jack on one end (to plug into the Tablet PC) and a Coax plug on the other (to plug into the 3808) and made the connection. The trouble was, nothing happed – no music emerged from the amplifier. I tried all the settings on the interfaces at both ends – the Tablet PC and the AVR-3808. Result: nada, zilch, nothing – no sound at all.

Luckily, Google is my friend. I entered the search string “HP tx2000ed S/PDIF problem”, and the very first result told me what was wrong. I had assumed that the 3.5 mm jack socket on the front panel of the Tablet PC was for a coaxial connection of the digital signal. After all, the other two 3.5 mm sockets alongside it are also for copper-wired connections. Nope, wrong; it’s actually an optical connection, and doesn’t use copper but fibre-optics. There is, of course, absolutely nothing in the HP documentation to point this fact out. Thank you Google*.

HP – pull your socks up and produce decent documentation.

* Of course, entering the same search string into Microsoft’s Live Search produces no results at all. Sigh. Live Search still sucks.

Last month, I wrote about some of the ways in which consumer technology doesn’t always work as promised. Today I’ll continue with the saga of the SNAFUs I’m encountering in my quest to have a media network in the house. I should start off by pointing out that today’s episode deals with cutting-edge features of products that are not in their final state, so it’s hardly surprising that not everything works as it should. Still, I post this as a counter-balance to some of the rah-rah blog posts that I’ve seen to illustrate that things aren’t always as wonderful as they seem.

Today’s topic is the “Play to” feature that will be in the upcoming version of Windows Media Player that will ship with Windows 7. That means that when browsing my music library, instead of choosing a track (or an album) and having it play on my computer, I can send it to be played on the Denon AVR-3808 that sits at the heart of our home’s audio-visual system. What I see on the PC is something like this:

Let’s take a closer look at the “Play to” window:

Here you can see that a track from a Kate Bush album is being played through the Denon AVR-3808. At the bottom of the window are the playback controls. The “Play”, “Pause”, “Stop” and “Track skip” buttons work correctly. In theory, I should also be able to set the volume level on the Denon via the volume control here, but this currently has no effect. This is probably because it’s an attribute in the new version 1.5 of the DLNA specification. The Denon is currently only certified to version 1.0, but a future firmware upgrade should be able to take care of this.

Well, this was all very nice, thought I, I’ll be able to assemble Playlists on my Tablet PC and use them on my Denon. But there’s many a slip ‘twixt cup and lip… I found that many tracks simply would not play on the Denon. When I tried, the “Play to” window would report that an error had occurred on the Denon, like this:

As you can see, it’s not a particularly informative error message, and looking through the error logs on the PC using Event Viewer didn’t reveal any more information that I could see.

What was going on? Further experimentation revealed that some tracks worked while other tracks didn’t – and it was consistent. Those that worked, always worked; and those that didn’t, always failed. And just to be clear – all of the tracks worked when I called them up off the Media servers using the Denon directly. But when I sent them to the Denon via the “Play to” feature, some of the tracks would always fail.

Finally, I found the correlation. The tracks that work were encoded using the default Windows Media Audio codec, encoding at a bit rate of 192 kbps. Tracks encoded using the Windows Media Audio Pro codec (also at a bit rate of 192 kbps) and those encoded using the Windows Media Audio Lossless codec (which uses higher bit rates) always fail with the “Play to” feature. This is a bit of a bugger, since these days I always use the WMA Lossless codec to rip my CDs to my Music Library.

So, to summarise:

As I said at the beginning, Windows 7 is still in Beta, and the Denon has not yet been certified to the new 1.5 version of the DNLA specification. So the problems could lie in either of them or both. But I do find it interesting that the Denon has no problem with all forms of WMA codecs when the files are streamed directly to it, which leads me to suspect that the issue may well lie with the current Beta of Windows 7. Whatever the cause, I hope that it gets resolved soon.

Important Update, 13 March 2009: I’ve discovered that I am in error in believing that the Denon works directly with WMA Pro and WMA Lossless streams – it doesn’t. The reason why I thought that these were working when streamed directly to the Denon (as shown in the table above) is that the streams were actually being transcoded into PCM format on the fly by the Media Servers I was using. Clearly, the servers were negotiating with the Denon over a supportable format when talking directly with the Denon. When using WMP12’s “Play to” feature, there are three devices in the chain, and a proper negotiation is not taking place. So, the server sends WMA Pro or WMA Lossless to the Denon, which can’t dealt with the formats, and the process fails.

Second Update, 14 May 2009: Using the Windows 7 Release Candidate, I’ve found that there is are scenarios where the format negotiation will fail, and ones where the negotiation will succeed. It’s all down to how you access your music files in Windows Media Player, and what the media server is. I’ll document all this and add it as a fresh entry into my blog… It’s now posted see Fun with Technology – Part IV.