On the right track

If you’ve been using digital music for a while then the chances are you’ve endured file format problems at some point in the past. Conversely, if you’ve just bought a mobile audio – or MP3 - player for the first time, you might be unsure about how these formats work, which format is good for what kind of use, and what files are capable of being transferred between devices. As ever, Windows is here to help…

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By  Matthew Wade Published  April 2, 2007

|~|ipods---m.gif|~|The iPod supports AAC (up to 320kbit/s), MP3 (up to 320kbit/s), MP3 Variable Bit Rate (VBR), WAV and Audible (talking book) audio file formats. Is does not support Microsoft's .wmv format however.|~|When sound waves are digitized for use by a computer they are translated into one of several file ‘formats’. These formats are easily described using three distinct categories: 1. Uncompressed audio formats retain - as their name suggests - their original size. Examples are WAV (wave), AIFF and AU formats. 2. Formats with so-called ‘lossy’ compression include MP3, Ogg Vorbis (.ogg), lossy WMA and AAC (with its .m4a and .m4p file extensions). 3. Formats that feature ‘lossless’ compression include Apple Lossless, lossless Windows Media Audio (WMA), FLAC and APE (Monkey’s Audio) formats. Let’s examine these file types in detail… No compression allowed Uncompressed audio formats contain exactly the same data and therefore use exactly the same storage capacity as when they were first recorded into digital form. The most well-known of these formats is the humble WAV (.wav) file. The native digital audio format of the Windows OS. You’re likely to find WAV files used online for sample chunks of downloadable audio, rather than entire tracks, and this is because of their large file size. A 3Mbyte MP3 file for instance might give you three minutes of pure pop; whereas a similarly sized WAV file will give you just 18 seconds of audio. The content inside a WAV file is Pulse Code Modulation (PCM) format, which refers to uncompressed digital samples derived from the original analog source. However, WAV files can also be used to store compressed formats including MP3, ADPCM, GSM, G.723.1 and others. (The way this works is that the headers in a file differentiate the type of content inside, however the .wav file extension is still used.) The Windows OS uses WAV files for general system sounds, such as the ‘ping’ you might hear when a warning window pops up. The WAV format is also widely used as the medium for professional recording and editing; when music companies create CDs for sale for instance, they first convert WAV files into the equally-uncompressed CDDA format. WAV files are effectively a variant of the RIFF bitstream format method that stores data in chunks. This Audio Interchange File Format (AIFF) format is an Apple audio file format used on Mac computers. It uses the .aiff file extension). Looking at lossy With the so-called ‘lossy’ method of audio file compression, a track is made more compact by excluding the audio parts deemed unnecessary for human enjoyment. For example, sounds below 20HZ in frequency and above 20KHz are withheld, as they can’t be heard by most people. Far and away the most popular lossy file compression format around is MPEG Audio Layer 3 – that’s the latest version of MP3 to you and me. Part of the MPEG-1 and MPEG-2 specifications, the MP3 compression format effectively compacts down CD quality sound by a factor of around ten, but whilst retaining the original fidelity. A 30Mbyte CD track therefore equates to a 3Mbyte MP3 file. Whilst MP3 sound quality is not up to the near-perfect audio standards offers by CD recordings, one reason this format has exploded in popularity is that, considering the file sizes possible, its quality is good enough for most listeners. After all, it lets us pack hundreds or thousands of songs into our pockets via MP3 players! As far as the bit rates that apply to MP3s are concerned, 128Kbps (kilobits per second) is the norm, although MP3s can be ripped (from CD) at rates of between 8Kbps and 320Kbps. (Again the higher the bit rate, the better the sound but larger the file.) On the down side, the MP3 format requires software and device makers must pay a royalty to use the format, which means the MP3 player you bought cost you more than it would have if the OGG Vorbis format – which is free to use and incorporate – was currently the de facto standard. The open-source audio codec, OGG Vorbis, leads to smaller files than the MP3 approach, and is also a lossy file format. Due to the fact it isn’t patented, and therefore doesn’t cost cash, the OGG is used a lot by video game developers anxious to keep their expenditure down. Less of the loss Third up is ‘lossless’ compression. This sits between uncompressed audio and lossy in terms of file sizes and sound quality. Less widely used than lossy compression, lossless audio methods such as Apple Lossless, WMA Lossless and FLAC reduce a full audio CD only to roughly half its original size (rather than the one-tenth size the MP3 format can manage), however in the case of lossless no high and low frequency sound chunks are discarded. As an example, WMA Lossless can compresses an audio CD to somewhere between 206Mbytes and 411Mbytes (at bit rates of 47- to 940Kbps). By and large equivalent to the original audio track, WMA Lossless is therefore the highest quality WMA format for ripping audio CDs; better than lossy WMA. It uses the same .wma file extension as other Windows Media Audio formats. ALL ABOUT ITUNES As Apple’s iPod remains the mobile music player of choice in this region, music lovers here need to know their way around iTunes. Easier said than done right? Not with this quick guide… What file formats does an iPod recognise? On the Windows PC platform, the iPod supports AAC (up to 320kbit/s), MP3 (up to 320kbit/s), MP3 Variable Bit Rate (VBR), WAV and Audible (talking book) formats. It does not support the Windows Media Audio (WMA) format. What about iTunes? When iTunes collates and centralises your music library to sync with your iPod, it converts tracks into AAC (or MPEG-4) format. This is why you might find you can’t play tunes from your PC’s iPod folder in Windows Media Player for instance. What legally downloaded tunes does the iPod support? Your iPod will only support songs that are purchased from Apple’s iTunes legal online download service. As this service hasn’t officially launched in the Middle East - in that we simply can’t buy songs from it – this is a cause of frustration for some iPod-holding, music-loving users. Creative others however simply burn their downloaded tunes onto a CD, rip them back into MP3 format and load them that way. How can I change the AAC format songs on my PC to MP3? You might want to do this so that you can load some of your favourite tunes onto a different audio player. The process is easy: first, change iTunes’ ‘Import Using’ default setting from AAC to MP3 by heading to Edit/Preferences/Importing (or Advanced/Importing) and choose ‘MP3 encoder’. Step two is to select the track you want to change in iTunes and choose Convert Selection. How can I copy songs from my iPod onto my PC? There are two methods of doing this. First, you can use a third-party app such as iPodAgent (www.ipodsoft.com) or iPodRip (www.thelittleappfactory.com), for which you’ll also need Microsoft’s .NET Framework installed (www.microsoft.com/downloads). Alternatively, due to the fact that an iPod is effectively a type of hard drive, you can copy your files across using Windows Explorer. First however you must sort out two issues: • First you must open Explore, head for Tools/Folder Options and choose the View tab. Then check the ‘Show hidden files and folders’ option. • Second, you need to know where to look, but it’s not a tricky one as the music on an iPod is stored in the iPod_Control/Music folder (which you’ve just changed from hidden to shown). Inside this folder are numerous others called ‘FO’ all the way to ‘F50’. In these folders you'll find your songs. ||**||

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