Order of the Bath

I have finally had enough with Windows Media Player messing me about. The issues were

• Even though I operated every available switch to stop it, it continued to contact the internet to get what it thought were better track listings and cover artwork even if I had set them manually.
• When changing tags, you could never actually tell when they would make it into the files. The library database showed the correct information but the song files themselves may not be updated for hours, during which time, WMP had to be left running. Not a lot of use when my Sonos system gets its information directly from the files.

Maybe I was doing something wrong but I couldn’t figure it out. Anyway, now I have stopped using it. After asking around, the consensus was that Media Monkey was the best available, largely because you could customise it (trivially) with skins and (functionally) with scripts. The changeover was clean and painless and all the information loaded into the very fast database with no trouble.

I like a simple interface so off came the baby blue skin and back to windows default styling and all my earlier reservations about it vanished. Once I found my way around the powerful options and commands available I was able to clean the library up properly. The missing features that I wanted, organising classical music by composer and all music by the album artist rather than the track artists were easily added using the Magic-Nodes script. I will post the configuration lines for this another day.

Once version 3 is available, which adds navigation by cover art then I will be fully happy. I have purchased a Gold licence, not so much for the extra features it offers but to support the team developing it.

As I have written before, the Sonos is a great system for distributing music around your house. The current range consists of three items; The ZP100 player which just requires a pair of loudspeakers to play the music, the ZP80 player if you want to provide your own amplifier and the CR100 controller which is a sophisticated remote control. A weak point from the marketing point of view was that you had to use one of the ZP units (normally the cheaper ZP80) to connect to your computer network even if you didn’t want music in that room. In large houses you might also need one to act as a wireless relay to get the range you needed. This was seen as a waste even though, by buying a bundle, it was actually costing very little (less than £100).

It hasn’t been announced yet but it looks like the gap will be filled with a new bridge device (thought to be called the BR100) which will be a cut down ZP80 (i.e. without the audio output option) and at a much lower item price. To some extent I imagine that it is a bit of a loss-leader, or at least very low margin because there is not a lot to be left out—just the DAC, ADC and some analogue circuitry, but it is possible they will also leave out the local storage of the library index. The price, however, would need to be significantly lower to be seen as a sensible option.

I suspect that the margins on the BU130 bundle were getting to be too low so, together with this release, I would expect to see a new “Starter Bundle” consisting of a BR100, a ZP100 and a controller; a direct entry into the Sonos world for one room priced at about £600; add more rooms for £250–£350 a time.

This is a move in the right direction but still does not address the issue that it is a geek or professional installer system. The reason is that it is not a stand-alone package, it needs a lot of non-Sonos bits and pieces to make it work. As I mentioned in the previous article, it needs a broadband connection, a router with DHCP, some disk storage, a CD ripping mechanism and library management. All of this is computing stuff and puts the layman off. There has been some debate as to whether Sonos could make a box to reduce the geek aspect of the system a bit. opinions vary, as you would expect; the options run up to a fully integrated “library device” which includes router, hard drives, CD player/ripper, integrated auto-tagging (naming of tracks, artists and album cover art) with perhaps a keyboard socket and screen for editing.

There are many issues

• In the near future, broadband connections will come with a router integrated. This is already the case with the heavy promotion of wireless systems.
• A disk drive will never be the right size for everyone so do you just provide USB sockets for external drives.
• With disk drives you have to consider the noise, but integrating with the bridge rather than the player should solve that.
• Any storage system must have a backup facility as they are not reliable enough.
• The US people are suggesting that CDs are becoming obsolete and everything is moving to download and Rhapsody-like streaming. In Europe that is not happening quite so fast as it is bogged down with copyright issues.
• In my opinion, the one task that really needs a computer is library management and tag editing. Having to provide a decent dedicated interface would be a step too far. For the mass market user it won’t be necessary (often) as thy will have mainstream music which will be auto-tagged successfully.

My conclusion is that the best route for Sonos to take would be to work with one of the NAS manufacturers and come up with a re-badged or endorsed product which fits in with the Sonos style, plugs straight into the back of the BR100 and sits on top (or underneath as it is likely to be heavier). Very little development would be needed; it just needs to be a properly conformant CIFS NAS device with provision for two hard drives (perhaps with a range of sizes) and a RAID mirroring capability. Perhaps a little modification of the install procedure would be needed integrating with the Sonos controller to make it easier. Now with joint marketing you can put together a true starter system dedicated to music—just add the music.

I would suggest leaving ripping and library management to the existing software on the home computer. There is a lot of choice and people use a particular one for a variety of reasons; the overlap into other technologies such as portable devices and video is too great. It is true that this will still leave out people that don’t use computers but I am not sure that they would be interested in this type of system anyway. For novice users, all home computers come with suitable software pre-installed and a set of decent beginners guides to the most popular solves most of the problems.

• One final plea—it is about time the controller came with a free cradle. Even though the cost is a small fraction of the total, it is seen as a rip-off.

I have a collection of music tapes; not commercial ones but bootlegs; every now and again I get a twinge of guilt.

Looking back at the history of this, my collection started when I was a poor student. I spent a significant portion of my grant on buying records. (Aside for younger readers: a grant is something the government used to give you to help with your further education, not to be confused with a loan. I don’t have any feelings of guilt over that, my education didn’t suffer in any way due to lack of funds and it was probably better for me than booze). Friends of mine did the same and, as I had a tape recorder (a big reel-to-reel thing), I recorded copies of theirs which increased my collection at lower cost. It was always my intention (honestly) to buy the records when I had the cash.

Then came the cassette. I adopted this format late and reluctantly because the quality at first was awful. It only improved a little later. My reel-to-reel recordings were transferred to the compact medium and the big beast put away in a cupboard. I remember at the time buying some of the records to replace them as I had a good job by then; but many were deleted and unobtainable.

Around this time (mid 1970’s) I had new friends with their own record collections. They had great recordings that I didn’t have and these were no longer obtainable either—so I took copies. The justification now was definitely that there was no other way to obtain the record.

Here we need a little political history. There has been an intermittent debate over home-recording rights for at least the last 35 years since the home cassette recorder became popular. The argument from one side was that we were stealing from the musicians—Remember “Home taping is killing music;” and on the other hand that the record companies were profiteering. The latter argument was boosted by regular stories of how musicians had been tricked into bad contracts. Every now and again the idea of a “home taping levy” on blank cassettes was brought up but it never came to much. There was a brief revival with a levy on blank audio CDRs but that is now dead as no one uses them any more, everyone uses ordinary data CDRs. It was really silly when it was apparent that the same companies who made the home recording equipment (notably Sony and Phillips) were also the owners of the record companies complaining about home recording. Now the attention is on downloading from the internet and sporadic attempts at prosecution. It is my firm belief that home recording boosts record sales. Without access to other collections over the years I wouldn’t have bought anywhere near as many for myself. There is also the argument of duplicate media for different locations but I have never got into that, not trusting cassettes to the car for instance.

Back to my story; In the 80’s I was doing a lot of music for parties, initially for children at the local schools but also for 21’st birthdays and wedding anniversaries. My trademark for this non-profit service, at least for the adult ones, was as a “human jukebox.” If there was a hit from the 60’s or 70’s then there was a good chance I would have it and could play it. A lot of the more obscure ones were (are) on tape obtained from scouring friends collections.

In the last 10 years I haven’t listened to music very much at all, but I have noticed a change in what is available. Suddenly all those records that were deleted only a few years after they were issued were being re-released on CD. I bought a few and retired the tapes but not with any great enthusiasm.

Recently two things have happened. I am going digital and we have been clearing out some cupboards and came across all the old reel tapes and the recorder. The recorder is still working fine—no rubber perishing or other problems, though it still has an intermittent fault with one of the playback amplifiers and some of the knobs are missing. More sadly, I have discovered that I had erased some of the tapes after transferring them to cassette and also that the lists of what was on them have got lost. It takes a lot of internet searching to identify recordings and I know that I will never find out what some are (I had a brief liking for atonal and “musique concrète.”)

So, at the end of it all, my Christmas list this year will be filled with requests for old and obscure recordings to try and replace them on CD. That will be a challenge for the children. The unobtainable I will digitise from the best copy I can find and I am only resorting to internet downloads when the CD I own refuses to rip.

Basic recording on a PC should be a fairly straight forward task. There are plenty of tutorial web pages around which tell you how to connect your equipment, such as a tape player, to the line-in socket (not the microphone socket) with the appropriate lead. Some even remember to remind you that most turntables require a special pre-amp.

There is, however, a big gap in most instructions (the ones I link to above are the better ones). I will use the standard windows tools as an example but your sound card may provide its own version. When setting up the recording you are presented with a “Recording Control” window (one route to find it is Control Panel—Sounds and Audio Devices—Audio—Sound Recording—Volume.) On here you would un-tick the Microphone Select and tick the Line-In Select then, just above it is a Volume control. What do you think it does?

There are supposed to be standards for audio interconnection but they have not been consistently adhered to by manufacturers. In the golden years of Hi-Fi (mid 1970’s) there was a de-facto line-level sensitivity of about 200mV and you could buy virtually any combination of equipment and it would connect together. This was the boom of mix-and-match. Prior to that it was a bit more hit-and-miss but the critical change was when the CD player was invented. Whether it was to hype the supposed quality of CD or some other reason I don’t know but they consistently had a much higher output. People connected them to the AUX sockets on their amplifiers and were blown across the room; isn’t it loud and clear! But after that, they had to remember to turn the volume down when switching over to CD; I am still doing it. This didn’t matter a great deal because the analogue circuits are flexible enough to cope though the more discerning can tell that they are really being over-driven causing a brittleness to the sound.

Getting back to the PC, sound cards do seem to adhere to the standard which, by the way, is -10dBV sensitivity for domestic audio. Instinct would suggest that the volume control is like the record level on a tape recorder or the gain control on a mixing desk. That is mistaken; those controls are passive attenuators BEFORE the active pre-amp circuitry. The control you see here is a digital control AFTER the Analogue to Digital Converter (ADC). The important point is that if your input signal level is too high then the damage has already been done. The overload will have been converted into very nasty digital distortion. In fact the volume slider is practically useless as the standard one is not even calibrated with a zero mark. I presume that above a certain point it offers gain to boost signals that are a bit quiet but, unless you are mixing it with other input signals in real time (in which case you really need a lot more sophisticated equipment) then setting it below the imaginary zero mark is unnecessary—why would you want to waste any of the signal you have been given.

My problem is with an old reel-to-reel tape deck (remember them?) which is an early 1970’s model with a very high output. I realised when I bought a decent sound card that had calibrated controls (E-MU 0404), that I was well into the red before starting. So what to do about it.

You could follow some advice given and use the headphone out socket but some, like mine, do not have a level control, and even then you are subjecting the signal to an often low quality headphone amplifier. You could try sending the line signal via an intermediate pre-amp but this may pass the signal straight through unless you have an adjustable line level output; mine doesn’t, and in any case it would be a bit of a nuisance to extract it from the Hi-Fi system. A third possibility is to use a mixing desk. These are designed to handle a wide range of input levels but not many people have one in the cupboard (and I discovered that mine was broken).

The ideal solution would be a passive attenuator between the deck and the line-in socket. I have found one cottage industry maker of these which he calls Goldenjacks. He does them primarily for the audiophile improvement of CD reproduction but he reports that he is selling more and more for our purpose. Mine haven’t arrived yet but I have ordered a pair of -10dB “source end” plugs and I fully expect them to do the trick. I thought initially that I would need a variable control but really it is a case of you either need attenuation or you don’t; in which case they can be removed. If you need more than 10dB (1/3 the signal level) then you have a more serious problem.

After we cleared out and re-carpeted the study, it was always our intention that it should be used as a dining/entertainment room but it had been lacking any music system. I was not looking forward to running loudspeaker wires from the room above where the Hi-Fi is. Even the family dining room was inconvenient since, though I had wired it up many years ago, it was a bit of a bind having to run up and down the stairs to change CDs. How we managed in the days of vinyl I don’t know—fitter then perhaps.

Another possibility was to install a mini system but I have always been fussy about sound quality and, even then, we would be bound to get into a state where the record we wanted was always “in the other room.”

A couple of years ago I had heard about networked media players when they were in their infancy and, though I didn’t like the idea of having to have the PC switched on, this was the incentive to look at them more closely. The first I saw was that Richer Sounds had a Phillips model for £99. This would require amplifier and speakers but investigations showed that the quality wasn’t great. looking at the market more seriously the front runner seems to be the Slim Devices Squeezebox at about £250 which has decent D-A converters. They also do the Transporter which is a serious audiophile device but way out of my budget. All these type of systems work the same sort of way. They use the UPnP network system to communicate with the media player on your PC to pick up your library of digital music, sometimes direct from your media player or sometimes using dedicated software. This is transmitted over your network, either wired or wireless and then converted to analogue where you want it to be fed into a traditional Hi-Fi amplifier. You can also get dedicated media servers which handle the UPnP protocol and avoid having to have the PC switched on.

It was around then that I discovered the Sonos system. At first sight it looked like a “Mercedes” range—what everyone wanted but couldn’t afford. It had a very good reputation for quality, ease of use, flexible with a responsive support team—but expensive. For my situation, this proved to be an illusion. I already had a (plain) file server with big disks, a network with router and broadband connections. To set up a UPnP system the way I wanted it would have meant replacing or adding a compatible server and disks. The Sonos system bundle 130 (at £700) comes with an amplifier built in (so just add speakers) and would give me two rooms of quality music which would mean I wouldn’t have to use the grotty PC system in the office (despite all the hype and marketing, these are never Hi-Fi). It also comes with a very slick wireless remote control which appeals to the technical and non-technical alike.

So I bought it.

How does the Sonos work

The philosophy behind it is rather different to most other media players. It is first and foremost a Hi-Fi system so attention has been placed on sound quality and convenience and minimising the technical input to a step by step “Getting Started” sheet.

Although it is possible to set up a system with just one player, its strength comes with two or more (up to 32) communicating around the house. One needs to be wired to the network containing the router, internet connection and server. This can be used as a player, but also acts as the gateway for the rest of what they call “Zones” and streams all the music on demand. It can use cable interconnects, for those with the luxury of a house with structured wiring, but it comes into its own using the built in wireless system. This uses the same frequencies as 802.11 Wi-Fi but they use a proprietary protocol which is optimised for music streaming and automatically invokes a WPA standard encryption scheme with no interaction with the user. It chooses the best channel for itself, avoiding interference from neighbouring wireless networks.

The star of the show is the hand-held wireless controller which has a 3.5″ colour screen. From this you can control what is played where and it also gives feedback of what is in the library, what is playing now and quite a lot else. It is possible to add multiple controllers to the system e.g. one per floor, but each one is universal and interchangeable.

Not surprisingly, each player is, in fact, a diskless computer processor with embedded Linux. Each holds its own copy of the library index in memory which makes navigation very quick, not requiring network traffic or server response. The ZP80 adds a quality sound card (with digital output) and a wireless adapter and the ZP100 also has a 50W per channel audio amplifier. They have decided to keep the dedicated software closed, only publishing the source of the modifications to the Linux as required by the GPL. This means that, unlike say the Slug, there not a strong “hacker community” though some have had a look at the controller interface and produced alternatives based on web browsers for PDA hand helds.

Conclusion

How has it worked out in practice? Was it the right decision? Overall, I think yes. The sound is good. It is reliable, easy to set up and fun to use.

Would I recommend it to any/everyone else? Yes, with reservations. The system they supply is very easy to set up. The bits they don’t supply are not. This is not just a Sonos failing but the whole concept. For Hi-Fi to have to rely on a dirty distant cousin, the PC, is a big drawback and will put most people off. Many people now have broadband, and many of those will now have a router because that comes with the wireless systems being promoted, but few actually understand it and installing a server, whilst a piece of cake for a geek, is not for the average domestic user. Perhaps the answer is for Sonos to produce a dedicated music server in the range, but somehow I don’t think they will because it is only half the problem. There is the library creation and management which requires the use of the PC and software such as Windows Media Player; I have written earlier about the headaches and problems using this and, unless Sonos unexpectedly expands the role of the Desktop Controller (a PC version of the remote control), I don’t think they want to get into this end of the market competing with Microsoft, Apple and Real.

So it will appeal to the already geeky, and perhaps to those having been brought up on iPods and suchlike, moving onto more serious stuff, but for the average casual music listener, probably not. The resellers have found a market, however, in processionally installed systems. They can do all the planning and setup and, so long as the customer only buys new mainstream CDs, they are easily run with a little instruction.

As for ourselves, now we are started we are already planning future zones and how to get some of our rare vinyl onto the system.

Appendix—the downside of the Sonos system

• It doesn’t handle WMA Digital Rights Managed (DRM) music well—the stuff you buy from Napster, and DRM music from iTunes and Rhapsody is not supported at all.
• The support for internet radio is there but, in the UK at least, is a bit patchy. It doesn’t support the BBC’s Listen Again.
• The advertised streaming music services, Rhapsody Live, Pandora and Sirrus, are USA only.
• By the standard of the iPod, the controller is a bit on the chunky side.
• It requires a router with DHCP, a broadband Internet connection, an available file share, preferably a file server, and a PC (or Mac) to rip the music and manage the library.

Appendix—the upside of the Sonos system

• Any file share will do, not a PC or dedicated music server
• Most well known file formats are supported; MP3, WHA, Ogg, Flac, WAV, Apple etc. The only notable exception is WMA lossless and, as mentioned above, DRM downloaded stuff.
• Use a high bitrate format and the sound quality is excellent. Whether it justifies the lossless formats like Flac or Apple Lossless, my ears can’t tell.
• It is dead easy to set up; plug it in and press two buttons, tell it where your music is and you are away.
• The controller is unmatched by any other system.
• Music “Zones” can run independently or in combination with any others right up to a house party where every system is playing the same thing.
• The wireless range is excellent and, with careful positioning, even coped with a two floor jump in our solid Victorian house. Multiple zones are a breeze as each one acts as a relay for the next, all perfectly synchronised.
• Each player comes with a 2 or 4 port Ethernet switch so, as a bonus, your computer network is distributed around the house for free.
• The internet radio runs independently of the PC and does not require plugins or anything like that.
• Updates are handled directly across the internet and usually transparently.
• The support and user forum are first class
• The green credentials are good with everything possible shutting down when not in use.
• Although they don’t advertise it, it is possible to run it without the internet connection after the initial setup.

Sorry about the gap, it has been holiday time here.

Creating a music catalogue is something that has bothered me for decades, ever since (or soon after) I first started my record collection in school. There just seems to be no logical way to do it, I don’t know how libraries manage. People have always been confused by my record cabinets because I insisted on indexing solo artists by surname so James Taylor was under “T” (but of course Jethro Tull was under “J”). Mixed artist compilations have to go at the end because there is no other way. Classical records have their own section ordered by composer and, again, mixed records are put to the end.

Doing the same thing for an online library is even harder. You would have thought that a lot more thought would have been put into it; perhaps other software is better but Windows Media Player is infuriating. It does a good job of ignoring the “The” from the front of everything but insists on sorting everything else strictly alphabetically so James Taylor ends up under “J”. The file system is first by artist, then album and finally track and this works quite well (and is largely transparent anyway). What the system does have is separate indexes for each, and also Composer, and Contributing Artist (the artist on each track) if you want it.

It is when you come to do classical recordings that it runs into serious trouble. The first problem is that there is only one catalogue—so, although you can put in the correct composer, if you look at the composer index you find it is cluttered up with people like Neil Sedaka from the popular catalogue when all you want is Brahms and Liszt. On top of this you have the problem that classical works are generally broken into movements which are not separately named and the pieces themselves can have very long titles which often includes the opus, key, instrumentation and sometimes a nickname. Then, what do you use for the “Artist”? Is it the composer, conductor, orchestra or principle soloist—I have seen all of these used. There are separate Conductor and Composer fields so I have tended to use either the orchestra or the soloist in the Artist field, whichever is more appropriate. The downloaded album information is very inconsistent and, for classical recordings, quite often wrong.

I thought I would look at Windows Media Player (WMP) to see how good it was before considering alternatives. After all, you can’t (easily) remove it from your PC even if you don’t use it. It is surprising how little information there is out there about this other than the official Microsoft Guides or rehashes of them. Just why I am looking at it now, having ignored music on the PC for all these years, I will leave to another post.

I started with WMP 10 which is what I had available and my first impressions were very good. The controls are straight forward and clear. I don’t have a lot of time for skins, the player is not what you want to look at and it just hides all the useful controls, nor do I really want to hide the menu bar though, once it is set up the way you want it, you won’t be using it much as all the day-to-day commands are available elsewhere.

Once you have set the “Rip” destination to what you want (it defaults to My Documents\My Music) and chosen the format and bit rate, creating the files is all automatic. It uses the file structure <artist>\<album title>\nn <track name> by default (where nn is the track number) which makes things quite easy to find and the database allows you search on other criteria. Choosing the format and bit rate is largely a matter of personal preference. Of the ones available I rejected WAV because the files are large and the support for tags is limited. I rejected WMA lossless for other reasons so there was a practical choice between WMA and WMA Variable. The latter is supposed to be higher quality for any particular file size so I set it to that and the maximum bit rate. This requires around 125MB for a typical CD. If you are playing back using an onboard sound card and budget speakers you can get away with a lot less than this though you should think ahead for future requirements to avoid having to go through your collection again later. In WMP 11, the popular MP3 format is available but is generally thought to be slightly lower quality than WMA for the same file size. There is no reason why your library cannot contain a mixture of types depending on need and availability; for instance you may need a smaller format if you are loading them onto a portable player. There are other formats which I won’t be considering in this article as WMP doesn’t support them.

Most file types allow for the embedding of meta data; tags which describe the music. These range from the specific—song title, artist, composer etc.— to the more subjective such as genre and style. The ability for WMP to find some of these details online (based on the nearly unique disk serial number) was very good but I found that obtaining the Album Art was rather intermittent. The record so far, having ripped 24 albums from a wide a variety of types, is:—

• Full information available, including artwork—6
• Most information obtained and correct but cover picture downloaded from Amazon by hand—16* (only one typo spotted. It even found the details for a Sue White Cornish Folksongs album which surprised me)
• Faulty Information (wrong and missing tracks)—1 (Hayseed Dixie—A Hot Piece of Grass)
• Track names only, rest wrong or missing, no image on Amazon—1 (v. old compilation album)
• No information at all—1 (Sampler album bought from street buskers)

The most frequent error was a missing date. This is disregarding information that I have never seen such as Copyright, Language, Key, Writer and Conductor, but perhaps I haven’t loaded the right type of disk yet.

What I can praise WMP for is that it is very easy to alter any of this information with just a “right-click Edit”. If you have the “Rename and rearrange music using media information” flag set then it also tidies up your library automatically in the background. Other important options to set are “Update my music files from the internet” but NOT “Overwrite existing information” otherwise you will find all your edits disappearing. Similarly you should think carefully before using the right-click “Update Album Info” command as this also overwrites your changes.

An aspect that I have not yet fully understood is the Data Provider. This is one of the optional fields you can display and most often it is “AMG” (All Music Guide) or AMG/Microsoft but sometimes it is “User Feedback”. The information from the latter is generally accurate but incomplete. The errors with the Hayseed Dixie album were possibly because it had detected another edition. Checking the AMG database by hand it only has what is presumably the US edition and the UK one must be different. With WMP 9 and 10 you could select “View Album Info” and then select or reject different alternatives if they were available. There was also the option to edit this information directly which is presumably what was used to create the “User Feedback” Data Provider information but I am not sure where it went. As far as I can tell this facility has been dropped from WMP 11. The help file and online guide still talks about “Find Album Info” but the option is not present on the menu nor is the prominent “View Album Info” button.

The “Genre” tag is really perverse, even to the extent of two disks in a double album or the same disk in different editions having different values; this is the field I find myself altering most often. Really this system is not sufficient to categorise music properly as, quite often, an album can fit a number of pigeon holes. For instance Andrea Bocelli—Romanza comes in as “Classical”. That is certainly wrong, though he does also record Opera. The songs are in Italian so perhaps it should be “World” like Edith Piaf. Iona is marked as “Religious” which is right but that doesn’t say anything about the style which I would put in the same group as, say, Enya which is marked as “New Age” whatever that means. With such a limited system I don’t think they can win, just as record shops could (can) never sort out their racks rationally. I see that the AMG database has quite a sophisticated “Styles” and “Moods” system but this doesn’t find its way back to the WMP tags.

Finding the album art was better for recent (last 5 years) and mainstream disks but even then it failed on quite a few. It doesn’t seem to get these from the AMG database but some other source so perhaps that is not as comprehensive. As I have fiddled with the settings so much on my machine, I tried on Mary’s laptop and this seemed to be a bit better as was my work machine (WMP 9) even though it is behind a corporate firewall. To try and reset my machine I have installed WMP 11. This may have been a mistake as it now seems to find even fewer but I haven’t done a systematic analysis. As a minimum you need a file called “folder.jpg” in the album folder in the library and it can be any size. The automatic system also creates AlbumArtSmall.jpg (about 72 pixels square) and copies of both files with some sort of randomised file name. It is also possible to embed images in individual track files but support for this in media players is mixed.

[update: I think that there may have been a temporary problem somewhere. Asking for an “Update Album Info” today found the art work for a further 9 discs.]