In yesterday's post I had mentioned that I get questions on the two compression types, lossy and lossless. Some have questioned the term compression and wonder, if it's compressed how can it be lossless? Is it a marketing scam or is it real? Probably worth spending a few minutes on this subject.
Lossless is indeed lossless. This means an identical copy can be extracted once uncompressed.
If you've ever gotten a ZIP file you're already familiar with compressing data. You would never expect to unpack a ZIP file and have your picture, text or document anything less than perfect. Audio compression of the lossless nature is the same.
The best known lossless compression schemes, FLAC (Free Lossless Audio Codec) and ALAC (Apple Lossless Audio Codec), are both able to compress a music file into about half the space of the original. Uncompress it and the bits are identical. There are other lesser known schemes just as accurate too, like MLP (Meridian Lossless Packing), WavPack, TAK, Monkey's, WMA, OptimFROG, TTA, among others. The list is long.
There is a lot of talk amongst Audiophiles that despite the fact lossless files are unquestionably bit perfect, they don't sound the same. How could that be? Well, for one thing, the amount of processing resources required to unpack a lossless file are far greater than those playing the original WAV file. If for no other reason, the extra number crunching impacts noise, jitter and increases power supply demands. So while the bits are identical, the playback demands are not.
If you download a compressed lossless file, uncompress it, and place it on your hard drive, that file will now sound identical to the same file on the same hard drive that had never been compressed. In other words, compressed or uncompressed the bits are the same.
Playback of compressed bits has different demands than playback of uncompressed bits. Hence, sound quality varies depending on the hardware reproducing it.
But that should be no surprise.