mp4 player choice

Choosing an mp4 player - I wrote this article for a magazine in autumn 2006

When I first arrived in Hangzhou in Spring of 2005, I was fairly hot-foot from a consulting company
where I'd been working on a design for a personal media player (PMP - a kind of mp4 player on steroids)
so I was very curious to find out what the selection of similar goodies was like in the world's mecca for
consumer electronics manufacturing. To my great surprise the answer was: no selection at all !
18 months on though, all has changed and the choice of gadgets is rather bewildering. Even if you've
learned the necessary vocabulary to ask intelligent questions, many of those won't get an answer even
from the user manuals ( some of which do have an English translation ). So in the end, its only experience
of playing with them - let's face it they're really just toys - that develops the ability to choose amongst
them all wisely. So here's my distilled wisdom from over a year's experimentative purchasing in Hangzhou's
electronics malls.

Firstly, I'll explain the scope of my treatise - I'm not intending to talk at all about 'PMPs' - they're relatively
expensive, bulky and heavy. They contain a hard disk which accounts for the increased weight and can
store 10's of gigabytes. Nor will I entertain straightforward mp3 players - ones with small screens which
play just music or occasionally, at the top end, might be able to show photos. No, I'm concerning myself
here with players that fall between these two genres - that have colour screens and can be bought usually for
well under 1000RMB and in addition to playing audio can show motion pictures. For your money you'll be
looking at a 2inch or greater sized screen with hopefully at least 1Gbyte of storage space.

In autumn 2004, back in UK, I bought a 1G mp3 player - which was as big as could be found then, and the
price was 200UKP. Of course, it wasn't a particularly cheap brand, but the price was high as 'flash' memory
then was so expensive. Nowadays, the price of the raw memory chips has fallen by around a factor of more
than ten. Nowadays the difference in price between having 1G and 2G in a player is around 100RMB, so its
definitely worth paying that little bit extra if you can. The alternative is to find a model which supports a
plug-in memory card (usually mini-SD) - though that's not so essential now since the price of memory is
no longer in free-fall, rather on a steady inexorable decline.

So what's really necessary in terms of storage space ? Well as ever, it all depends on what you'd like to do
with your new toy, and it also depends on what features it has in the video department, as I'll explain a bit
later. For audio, if you have any pretentions towards sound quality, you'll be wanting to encode your CDs
at a bit rate higher than the bog-standard 128k settings. What do you mean you don't buy CDs, you just
download ? OK, so even then look for files that have been recorded in 'vbr' format. 'Vbr' stands for variable
bit rate - this means that the file is smaller for a given audio quality than for a constant bit rate ('cbr'). What
happens is that the software uses up more bits when there's a lot going on in the music, then for very quiet
or simple passages, uses fewer bits. In the olden days there were odd players that wouldn't play vbr files,
but I've not found one I've bought here which has a problem playing them. Variable bit rate with an average
of around 160k I've found to be fine for sound quality, and I'm fairly fussy. With a 2G player, this will give
you 25 - 30hours of listening to music. Of course, the battery is unlikely to last that long.

When it comes to storing movies, things are a little different. Firstly, the bigger the screen your player has,
the better the picture quality and so the more data that's needed to store your movies. I started out with
a player with a 2.2" screen which had 220X176 pixels - this popular size is called 'QCIF+' and many mobile
phones also have a similar sized screen. The next size up is QVGA at 320X240 and its the size I recommend
if you want to sit through a whole episode of 'Friends' at one go - watching a screen any smaller than this
for more than five minutes at a time makes me go boss-eyed! Next you'll be wanting to know where to get
movies to play. Well, if you're not a downloader, then the obvious source of material to watch is DVDs.
However DVDs are designed to play on TV screens which generally have resolutions of 720X480 (or better)
so you'll need some software to convert them to watch on a handheld player. Some (if not all) players come
with such software on a mini-CD. For enthusiasts who'd like to experiment a bit more, I'll talk about how to
do that next month with freely downloaded conversion software.

What to be aware of with movie files is the formats which a player supports, and here things get a little
technical. The type of movie file that these players will play is called a '.avi' file. That's a container for both
a video file and its associated soundtrack. The video file will be in mp4 but the audio soundtrack need not
be in mp3. Whilst all players can play mp3 sound files by themselves, not all can play an mp3 sound file at
the same time as mp4 moving pictures. Simply put, the battery powered processor in your player mightn't
have enough horsepower to do the job. If so, it will only handle mp1 audio which takes up to three times
as much space as an mp3 of the same quality, but needs less power to decode. What happens then is that
the size of your movie file comes to be dominated by its mp1 soundtrack, not the pictures! I found this out
the hard way, of course... So it turns out that a small screen player might actually be able to store fewer
minutes of video than a large screen one, even if the memory size is the same.

The other thing to watch (pun definitely intended) with players is how many fps they will show. 'fps' means
'frames per second' and this figure is a measure of the horsepower lurking behind that screen. A low number
of fps means your video will look distinctly jerky. I've noticed that manufacturers quoted figures aren't
always accurate either so it does pay to take along your own material on a mini-SD card (with adapter for
those players taking only SD) and ask to see it played. I've plagued many a couple of booth vendors for
hours with this ploy, the results of which I'll be happy to reveal next month....