Music for Mobile Games - Past, Present and Future

Monday, January 22, 2007

Posted by Jim Paterson

Music on early mobile games was often not much better than the annoying ring-tones we used to hear everywhere. No wonder people looked for the off switch! But as devices have improved in sophistication their music capabilities have grown significantly too, and many phones these days double as mp3 players. People now expect their games to be every bit as sophisticated as their phones, and that means games must look good and sound good too. You need to think carefully about the right kind of music to enhance your game, something that adds to the immersive experience and helps to keep the game-player coming back for "just one more game". And you need to find an experienced composer who understands the practical aspects of music on mobile platforms.

Past

It was about 4 years ago that I first became involved in writing music for mobile games. At that point in time most devices had passed the "beeping" stage and were able to play real Polyphonic music, i.e. they could play different sounds and notes at the same time. This was a big advance on the previous monophonic devices and meant that standard MIDI files could be used.

However the speakers in these devices were not quite up to the same standard as home or car hi-fi systems. They had a poor frequency response - shrill in the high frequencies and with very little bass. Composers could compensate for this by altering the pitch to better fit within the device capabilities, and changing the overall balance for example to boost the volume of the bass. Some instrument sounds were better than others and there was the need for experimentation to decide what instrument combinations worked best on the target devices. Another serious limitation was the limited amount of memory, which forced composers to be economical with their music. In practice this meant that the full benefits of polyphonic music could not be exploited - you needed to restrict yourself to one or two instruments or keep themes and loops very short indeed!

Present

So what has changed today? Well phone speakers have improved a little, but there's still a need for balance adjustment. It's more common these days for people to play games using stereo earphones and these are better at reproducing sound, but the composer must still achieve a reasonable compromise so that the music sounds good with either phone speakers or earphones.

While there is increasing support for the MP3 format, perhaps only 10% of devices support this music format currently. Games Developers don't want to limit the appeal of their games, and there is a tendency to develop for the "lowest common denominator". As a result, MIDI files are still the standard format for games music. Although there are new variations on the original standard, including Scalable Polyphony or SP-MIDI, these are still basically MIDI files. The main change is that memory capacities are significantly larger, so there is much more scope for larger MIDI files and the music can be both longer and more sophisticated.

Depending on the nature of the game, a wider range of music can also be supported. However games developers want to sell their games to as many people as possible, so the games and the music they contain need to be converted or "ported" to different devices. Some of those devices are more restrictive in their music capabilities and memory capacities, so the composer either needs to consider the SP standard or alternatively produce a number of different versions of their themes and loops. Typically the games and music will be created first for the higher-end devices, and then "simpler" versions will be created which play on more basic machines.

However there are still restrictions that composers and games developers need to be aware of. One of the most annoying of these is that the MIDI format does not support loops and the programming environments are inflexible and work on a file by file basis. If you want a 30 second piece of music to play continuously in a loop you play a 30 second MIDI file and then when it has finished, you need to play it again! This might not seem to be a major problem but in practice it means that there can be a small but noticeable gap between each repetition of the loop. If developers find this is the case, then composers need to use their musical skills to disguise this gap so that it is less noticeable. Other restrictions mean that it is generally not possible to play music and sound effects at the same time.

Case Study

Let's face it, there are always going to be restrictions. To a large extent creativity is about working within constraints and finding suitable solutions to a number of problems. This article is illustrated with graphics from a soon to be released game called "Rock'n'Roll" by a new Scottish based company called Tag Games.

The game developers had come up with a great concept where you rotate a maze to allow a character called Rocky to drop through and explore, picking up goodies and avoiding baddies along the way. The gameplay is instantly appealing using only 2 keys to control movement, though the underlying technology is quite sophisticated for a mobile game using smooth sprite rotation and scaling. Rocky is a wacky rock-shaped character and the graphics are bold and colourful with that same instant appeal. Needless to say with a title of Rock'n'Roll you need some Rock and Roll music to accompany it. Experimenting with different types of Rock and Roll it quickly became clear that the best match to the game was the early style of the 50s, but bright, up-tempo and simplified to suit the wacky character and the cute appealing graphics. So to sum up the concept, there's a Rocky character, a Rolling landscape and some Rock'n'Roll music.

The game has a title theme and 3 in-game themes to match the 3 types of environments that you can explore "Coral Reef", "Jungle" and "Mountain Top". Here are the 4 midi files used:

• Title Theme
• Coral Reef
• Jungle
• Mountain Top

These are the "long" versions of the loops for higher-end devices. Note also that these files have been rebalanced to sound better on PCs or MACs, but there is still the inherent problem that the actual sounds are generated by the target device.

Future

It is always hard to predict the future, but there is certainly a trend towards wider support of the MP3 format. Perhaps in a couple of years time we will see games on the market which exploit this trend. While large budget game titles (e.g. film tie-ins) might be able to use recorded orchestral music or chart songs, the smaller scale developer will still need to rely heavily on computer generated music. This is not as big a restriction as it might seem, because the sophistication of computer software is increasing all the time, and modern sample-based software instruments are increasingly used on music for film and television.

Enough of trying to predict the future - this is an opportunity to influence the future! If there are any platform developers out there, here is my wish list for the music capabilities of those platforms:

• Support for MP3 and other near-CD quality formats
• Support for a "loop" capability which doesn't create gaps
• Support for background music and sound effects at the same time
• And most of all, support for dynamic methods which allows the music to be adapted as the game progress

If you're wondering what I'm talking about with my 4th wish, the concept of "generative music" has been around on PCs for a long time. While some examples of this work by using random factors to influence how the music plays, the best examples allow a degree of creative control. Imagine for example that your character is wondering in an alien landscape. As you approach various threats or they approach you, the music might get darker and more threatening. Or perhaps it's one of those games where your avatar has a variable strength depending on energy or skill levels, or previous conquests. The music could continuously modify itself to reflect this status.

Now

I'll put these wishes on my wish list for next Christmas. In the meantime if any games developers are interested in using my music for their games, I can be contacted at jim@mfiles.co.uk and there are some examples of my music on www.mfiles.co.uk.

Jim Paterson