Multimedia flac Audio Compression - Worth the space?

Recently a bud back home sent me a compilation of some of his OSTs that he converted straight from the CD in an interesting file format I'd never seen before- flac Audio.

Apparently the big thing behind this format is that you can break 360 kbps with the utmost of ease scoring bitrates of as high as 1114 (from my own experience). However just for me to get his collection I had to wait almost a day for it to transfer- the few CDs in his ost ran over 2 gigs.

Amazed at the sheer size of these music files I sat down and began to examine the bit rates these files were running at compared to my standard MP3s to see if this crazy new file format was really all that and a bag of chips. Examine my attachment down below, we'll use that as our mathematics guide. My purpose? To examine the number of kbits per meg thus giving us a visual example of how good each file format is at compressing the original music data. Better compression compared against bit rate = smaller file size compared to music quality. I wanted to see if flac was worth the Megs it took up for its insane bit rate when stacked against a standard mp3 file.

Almost all of the flac Audio files I examined were variable bitrate files- which means that the kbps changed depending on what was going on in the music. This helps to bring the file size down. The mp3 file I used was not => The Mp3 file had a natural disadvantage. Because it had one solid bitrate the file would end up being larger that it would have to be if it used a variable bitrate. What's worse was that my MP3 file was 224kbps, not 128 like most people use as a standard. This meant a larger file and thus a less economic compression ratio.

The song I used for both file formats was Yoko Kanno and Origa's "Rise"- The opener for Ghost in the Shell: Stand Alone Complex 2nd Gig (might as well use an anime song, yeah?). For both cases the song length was 5.5 mins (5 mins 30 seconds)

flac Stats for Rise: min bitrate- 630 kbps. max bitrate- 1114 kbps.

Mp3 stats for Rise: bitrate- 224 kbps


My goal was to convert kbps (kilobits per second) to kbpmb (kilobits per megabyte). The more kilobits per mb the better the music compression- the more kbits of audio file we were compressing into each meg. The whole point of a compression program is to shrink as much music, with the highest quality possible, into the smallest file size we can get away with. The more kbits per meg the better the compression for the given file size.

So let the testing begin.

Let's examine example A- What you see is a conversion table. I am trying to take kbps and turn it into kbpmb. As you can see minutes and seconds cancel out leaving us with Kbits per Mb

For Example A I took the highest bitrate the flac file achieved, multiplied it by the length of the track in minutes, divided it by the total size of the track, and multiplied it by 60 seconds to account for the fact that the file itself was originally in kilobits per SECOND, thereby finishing the conversion into kbpmb.

For Example A the compression for the given file size was an impressive 9330.4569 Kbits/Megabyte. Not bad at all!

For Example B I took the lowest bitrate achieved and applied the same math. This time the resulting compression was not so good. Only 5276.6497 Kbits/Megabyte.

Example C I did the same math for my Mp3 version of the same song. Its bit rate about right at 8419.1344 Kbits/Megabyte. If you do the math a little further you realize that the Mp3 at that bitrate is squishing a little more than a meg per minute into each megabyte of HDD space. That's the whole point of compression!

Now the first two examples (A & B) are both really great and dismally bad when compared to my Mp3 and its static bitrate. Because the bitrate of the flac file was constantly fluctuating, in order to get a definitive answer we need to get the average of both those numbers to see how flac stacks up overall to Mp3.

Enter Example D- 7303.5533 kbits/megabyte. Not nearly as good as my Mp3.

Take the kbpmb and divide that number by the bitrate you’re running at to get some more interesting numbers. Mp3 compresses at 37.5848 to 1, while flac rolls at only 8.3752 to 1 at any bitrate.

The results of this test lead me to believe that flac compression is economic than Mp3.

Now compression doesn't mean anything if the audio quality suffers as a result, yes? When played side by side (flac Rise and Mp3 Rise) both files sound exactly the same through my sound system (Zalman surround sound headphones). The ultra high bitrates sound the same as our standard Mp3. The quality change is negligible. Now not everyone has a $500 surround sound system or $1000 headphones, so unless you have the best and want the best out of your audio files flac may be the way to go simply because of the insane bitrates. Your HDD space will suffer as a result, however.

I, myself, will stick with Mp3s until something more viable (maybe .ogg) comes out for me to test drive. The ultra high bit rates are pointless if you cannot discern the difference between them and the 224 kbps that Mp3 offers. What's worse is the average compression for flac is less than Mp3, which means you're wasting more space for the same relative file size per bitrate.

Second opinions and other dirty math are welcome from all.

~W