Isn it pointless to use gzip or bzip2 lossless compression on audio files?
It all depends on the audio file. It is true that using bzip2 on music ripped from a CD will result in poor compression rates on the order of about 5%. But since gzip and bzip2 are generic entropy encoders, the less information a file has the more it should compress in a lossless fashion. Here are some examples. • A quiet signal with much less than the 96 dB dynamic range allowed for in a 16 bit wav file will have a sample amplitude distribution that uses, lets say, half of the 16 bits. This audio file could of been stored as an 8 bit wav file without any loss of information, but it wasn’t, so using gzip or bzip2 will compress out most of that redundant information (roughly about a factor of 2). The same argument is true for a stereo file which is actually a mono file (both channels are the same). Even if the redundancy isn’t ideal, like the 8 bit and mono cases, an entropy encoder will still do a very good job. • Test signals like sine waves are very redundant and they compress very w
