What’s wrong with this picture?
You may trust Consumer Reports to test refrigerators and microwaves, but when it comes to computers and other digital gadgets, they just don’t seem to understand.
Look at the above graphic. In an article entitled How to make your digital music sound better, Consumer Reports tries to set out the differences between various audio file formats. One element they examine – and rightly so – is the size of files in different formats. They ask how many 4-minute songs can you put in a gigabyte of storage.
And their numbers are all wrong.
To start with, Consumer Reports claims that a 4-minute song in 256 kbps AAC format is 13 MB; it is closer to 7.5 MB. I’m not sure how they calculated; I just sorted my iTunes library by time, and averaged the size of 4-minute tracks (I’ve got plenty of them). Perhaps they’re looking at tracks to which they’ve added very large artwork.
So what about the WAV files? They’re a bit low, because 4-minute WAV (or AIFF) uncompressed files at CD quality are around 42 MB. (It also makes little sense to talk about WAV files; pretty much everyone who puts CD-quality files on a device uses FLAC or Apple Lossless, because they’re about half the size.)
As for the FLACs, since the size is variable, according to the type of music, this can vary a great deal. Also, Consumer Reports is looking at “high-res files” without specifying their bit depth and sample rate. I assume they’re talking about 24/96 FLAC files, the most common high-resolution spec. These files are much bigger than the average FLAC that most users encounter, which are CD-quality. The 4-minute songs I looked it, in 24/96, are around 80-90 MB. Again, they may have only sampled one or two tracks to get their numbers.
Finally, for the 24/96 AIFF files, they’re way off. As with WAV files, these are uncompressed, so, unlike FLAC or Apple Lossless, the file size doesn’t vary. According to this website, PCM files (WAV or AIFF) at 24/96 are 34.56 MB per minute; or 138.24 MB for a 4-minute file. That’s about 63% of the size that Consumer Reports claims. (I converted a 3:58 24/96 file from Apple Lossless to 24/96 AIFF, and it’s 137.8 MB.)
So, trust Consumer Reports, except when you don’t.