What formats should you save your files in?
Sensible advice for future-proofing
So far, we’ve explained the general principles of digital preservation. Hopefully you can now make some pragmatic decisions and take preventative measures to ensure you’ll still be able to open your files in many years to come. Taking our earlier advice about future formats a step further, here we offer you some specific guidelines about what formats you should use for the most common file types.
Photos
If your photos are in JPEG format, we reckon they’re safe. JPEG may not be an open format, but it’s so ubiquitous today, it’s hard to imagine the world will lose the ability to open it soon. (PNG, incidentally, is an open format, and it’s higher-quality than JPEG too since it doesn’t compress with a lossy algorithm – though that does mean the file sizes can be larger.) If you’re shooting in raw, however, you’ve got trouble. Raw formats are usually not only proprietary but unique to each manufacturer – so be wary. You could convert to DNG – this format isn’t open, but Adobe lets anyone use it for free. Lightroom can convert to DNG on import, or you can download the free Adobe DNG Converter.
Music
Even if we ignore music files that are protected by a DRM system, MP3 is proprietary, and may not always be accessible. AAC is also restricted, but support for it is more flexible. The open-source option for music is OGG, but iTunes doesn’t support converting files to it easily, so it will be a pain to get your whole library set up. The best way to go is actually likely to be Apple Lossless, since although it started life as a proprietary format, Apple made it open in 2011. You can copy CDs or convert iTunes tracks to it by setting the app’s preferences to encode in Apple Lossless and then right-clicking on your tracks to convert them.
Contacts
If you drag your contact details out of Contacts or Address Book on the Mac, they’re saved as v-Cards. These are little XML files with a VCF file extension, which should prove almost as robust as pain text files. For that’s essentially what they are – XML documents being just plain text files with special codes and characters to separate out and structure bits of the text. This means that even if nothing can natively open v-Cards in the future (which looks pretty unlikely over the decades-long timespans we’re talking about here) you can still open the XML documents and, with a little brainpower, search for and extract Auntie Mabel’s old address.
Documents
If you’re talking about documents that are mostly straight text with minimal formatting, your safest option is TXT – Pages, Word, Text Edit and basically every other text editor you can name can save to plain text. Try to choose Unicode (UTF-8) as the encoding method; it’s the emerging modern standard for the web and even operating systems, and it’s backwards-compatible with ASCII. For documents with formatting, save a copy as PDF; even if your app can’t export to PDF itself, you can ‘print’ to PDF from any OS X app. Although it’s a proprietary format, its ubiquity should mean it persists well into the future.
If your email app saves messages as individual files on your hard drive using a MIME standard, you might be safe keeping them as they are for the future. However, unless your email software uses a proprietary database to store messages (Entourage, for example), most email clients allow you to save messages as plain text or RTF. (Both formats are robust, but RTF is only really necessary if you need to save in rich text.) Having said all that, you should really consider actively migrating your email as technology progresses: most apps and services will have import features for common formats, allowing you to move to newer versions regularly.
Movies
The future isn’t so clear for video formats. Most video codecs are still both very complex and very locked down. The safest thing you can do is to make sure your movies are encoded in a format that is popular now and has a good future ahead of it. For the moment, that means H.264. It’s been Apple’s go-to format for encoding videos for years. If you have movies hanging about on your hard disk in weird, old formats, now’s the time to convert them to H.264 while you still can. Handbrake, VLC, Perian (hooked into Quick-Time Player) and MPEG Streamclip are handy tools for this task Finally, the open alternative to H.264 is Web-M – Miro Video Converter supports transcoding to it.
Archives
The good news is that the basic ZIP format is in the public domain, so we should be able to open ZIP files for a very long time indeed. The archival format TAR is open too, so we have high hopes for that. Other formats including the SIT files that Stuff-It creates, have a much more uncertain future. Frankly, though, we’d recommend the same thing for all: just uncompress your archives today. Compared to a few years ago, hard disk space is so cheap and plentiful now that your old files can probably abide on your drives in their full size. The Unarchiver (free) might help in that regard; you can still get Stuff-It Expander for free, too.