Just typed this now, so be prepared for updates!
Lostbok-BahnStormer's little "MP3 tips for 2008 or earlier RNS-E's":
General tips:
1) when building an SD card, start small and make sure it's working before you dump 400 songs onto the card.
2) remember that 512Mb was a fairly big SD card when then were designed, so @4Gb, you're hitting it with 8x more data than they expected people to use, so more songs can mean it loads slower when you first start up (see "M3U tips" on how to help this).
3) MP3 files are not all created equal: in particular ID3 tags: I know I've had to go into the properties on some files and remove special characters on the ID3 tags.
M3U tips:
1) I'm happy to check people's M3U files if you're having trouble, or I'll send you some sample ones of mine.
2) speed up loading a little bit by using M3U's (playlists) in the ROOT (not in each subfolder)
3) M3U files have to be the simple format (i.e. NOT the one with ## all over them) just the path and filename on each line.
4) you can spaces in file names and should NOT have quotes!
5) the files should NOT have drive letters and they use relative paths, so load them up in notepad or notepad++ and remove all the "E:\" or whatever your SD drive is set to - just use a search and replace, the first thing on each line should be the name of the folders, separated by "\"'s and then the file name, e.g.: Snow Patrol\Up To Now\CD1\101. Snow Patrol - Chocolate.mp3
6) don't be afraid to create M3U's from scratch: start with an empty txt file, use windows "power toys" SendToX to send the highlighted list of files to the clipboard (settings need to be "new file for each line" and "no quotes"), then just search for the SD drive letter name and replace it with a blank.
7) you can reference the same file in multiple M3U files if you're creating two versions of a playlist (kiddies censored version, etc).
Things that do NOT work:
1) >500 allocation units (songs+each folder+each subfolder+each M3U/other file = total allocation units) - I think it's actually closer to 400, even though something like 512 would make more sense...
2) special characters: accents like "é and in particular apostrophe's are the killer - they will make that MP3 disappear from the playlist list.
Things that DO work:
1) 320kbps
2) variable compression rate (songs that are 320kbps, but change to 64kbps when less detail is required)
3) some slightly "special" characters like spaces, "_", "-", "." within the file names are 100% fine.
4) I THINK these brackets are okay, "()" and "[]", but not "<>" and "{}", but happy to be corrected on this.
Other known bugs:
1) When you turn the ignition off, it will resume on the track where you left off, but the NEXT track will be the first on the card listing.
2) Your display will not say 4Gb or 4000Mb, or 4096Mb, but most likely 373Mb or 381Mb for a variety of reasons, read on if you dare:
a) Boring maths bit:
i) 4Gb is 4,000,000bytes according to media salespeople, but it SHOULD be 4*2^30=4,294,967,296 bytes if you're a computer.
ii) so your 4,000,000byte card is actually 3.7253Gb or 3814.70Mb, those numbers are the same if you're a computer (or me
).
b) the RNS only expects up to 512Mb cards, so only has 3 numerical digits, so it will only show you "373Mb", when it actually means 3.725Gb and wants to say 3725Mb... I have one type of card that shows "373Mb" and another one that shows "381Mb" (3814.70Mb=4,000,000kb)...
3) countless other little things
