FLAC - audio contents
FLAC files are the audio equivalent of ZIP files, squeezing all of the data into a smaller container. When we encode a master file (normally stored as a WAV) into the FLAC format, the encoder looks for data patterns within the WAV file that can be more simply represented in such a way as to preserve all the data but to reduce the filesize.
For example, if the encoder finds a row of 64 zeros in the file, it can say "64x0" rather than "000000000000..." etc. (This is a simplification to give you the gist of it.) When the file is replayed or decoded, these are correctly read back as all those zeros, and nothing is lost, even though a lot less room was needed to store that data. You can reconstitute the original WAV file with no loss of data at all, and if the original master was a CD file, you'll have a bit-perfect copy of the data on that CD.
Conclusion - a FLAC file holds identical information to our studio master file.
So what's the difference between FLAC and MP3?
MP3 files are often much smaller than FLAC files. This is because they compress the data in a different way, using a process called psychoacoustic modelling. This recognises that within the audio data there is a degree of redundancy - stuff that's there but can't be heard because other, louder sounds are masking them. These sounds are simply discarded, allowing for a much smaller filesize.
This kind of encoding, at its very best, should produce MP3s that are audibly indistinguishable from the original master files from which they were taken. However, there are different levels of compression, and the more that you discard, the harder it gets to fool the ear - especially with certain types of music and with high quality replay systems.
Pristine Classical has always taken the approach of using high quality MP3 compression, designed to match or surpass the resolution of our historic recordings. But with our FLAC files you can be sure you're not missing anything, as you'll have a perfect copy of our original master, with literally nothing thrown away.
Conclusion - an MP3 hold information encoded to sound as close as possible to our studio master file
FLAC vs. MP3 vs. WAV - file sizes
Here we see what a difference data compression makes to an hour-long mono recording from the 1950s:
|Original CD-master WAV
|MP3 LAME -extreme encoded
Remember that we're using a mono file here - the original master is a stereo CD-standard file where both channels are identical, and thus there is a big built-in redundancy for the compression routines to work with, as half of the data in the master file is duplicated.
However, this does give an accurate indication of the sort of download sizes to expect from our files. In this example we used Charlie Parker With Strings, which runs to 59 minutes and 29 seconds, and contains a lot of high frequency information that's hard to compress using a lossy format such as MP3.
Conclusion - MP3s are much smaller than FLAC files.
FLAC vs. MP3 - sound quality
Now take a listen to the difference - if you can hear it - between the file formats. Remember that FLAC and WAV files are played back identically - there is literally not a bit of difference between them when the FLAC has been decoded. Thus we're offering downloads of just the FLAC and WAV files for this example.
The downloads consists of the first movement of Mendelssohn's Violin Concerto, recorded in 1954 by Jascha Heifetz with the New York Philharmonic Orchestra under Guido Cantelli, live at Carnegie Hall.
If you need help playing the FLAC file, see our FLAC help guide here.
FLAC vs. MP3 - the verdict?
We strive to make our MP3 files of sufficiently high quality that you'll not normally hear any difference between these and a CD of the same recording. However, if you choose our FLAC files you'll be getting a download that is identical to that CD - it contains all the same information, just encoded in a slightly different way.
FLACs are bigger and take longer to download than MP3s. But if you need a smaller file at a later date, for example to use on an iPod, then you can of course compress your FLAC file to fit. FLAC files also cost a little bit more than MP3s.
Conclusion - The choice is yours - exact copy (FLAC) or very close copy (MP3). Take a listen and see what you think!
The XBMC Media Canter - A Universal Free Replay System
Pristine Classical recommends the XBMC Media Center software for all audio replay on all computer plaftorms. Click here for further details of this comprehensive, free, universal audio, video and photo replay software.
Postscript - about bit depths and sampling rates
Sampling Rate: At Pristine Audio we always work using a sampling rate identical to that of CDs - 44.1kHz. This is more than adequate to cope with the frequency range of the historic recordings we're remastering. As such there is no frequency loss when downloading any of our recordings or listening on standard CDs. We remain totally unconvinced of the merits of higher frequency recordings, ancient or modern.
Bit Rate: All of our recordings are processed at higher bit rates - normally 32 bit floating-point, though some of our software does use a 64-bit internal processing resolution. There is very good reason for this - with each process we expect some tiny rounding errors which, in a CD-standard 16-bit environment would eventually encroach on the fine resolution of the sound. Our processing has a dynamic range from -765dB to +765dB - this is a huge amount to play with! By comparison, your ear may just about manage a dynamic range of 120dB, equivalent to 20-bit sound, and a 16-bit CD has a range of 96dB.
When our finished 32-bit master is prepared for CD we use a process called dithering to optimise the resolution and reduce digital 'quantization' noise . This remarkable technique allows us to effectively squeeze more out of a standard CD, with a noise floor that represents something closer to 18-20 bits rather than the 16-bits of the CD. Given that our analogue recordings all have noise floors much above this, we can be sure that there they are being accurately represented in a 16-bit format, and thus we don't currently plan to offer them at higher bit-rates.
It should be pointed out here that no electronic audio equipment is capable of working at the theoretical dynamic range offered by 24-bit sound of 144dB. Beyond about 20 bits you're getting into a numbers game for the purposes of replay!
Conclusion - properly done CD-resolution audio is just about spot-on for superb audio reproduction, whatever the hi-fi industry might want you to believe.