Audio Compression
 

I used the Frequency Analysis function in EAC (Exact Audio Copy) to discover which was the best format for compressing audio. Obviously having it uncompressed is the ideal option but it is not always possible to do this on computers (generally due to memory problems), so ehre is what I found.

I used Wanted Dead Or Alive ripped from the This Left Feels Right CD layer of my SACD copy of the album.

This is the frequency analysis for the original WAV file:

http://members.lycos.co.uk/squirrelo.../01%20WAVE.gif

This is uncompressed so contains the full set of frequencies for the song.

MP2 128kbps:

http://members.lycos.co.uk/squirrelo...d/02%20MP2.gif

This is quite heavily compressed, and 128kbps seems to be a standard that people use, but as you can see most of the frequencies above about 15khz have been cut.

MP3 128kbps:

http://members.lycos.co.uk/squirrelo...d/03%20MP3.gif

Again I have used 128kbps and again it has cut frequencies this time moreso, cutting at around 14khz.

MP4 128kbps:

http://members.lycos.co.uk/squirrelo...d/04%20MP4.gif

This is the new standard of music soon to replace MP3 (probably), and is not quite as compressed, only cutting at around 17khz, but this is still a lot.

OGG 128kbps:

http://members.lycos.co.uk/squirrelo...d/05%20OGG.gif

It seems OGG is the best of the compressers I have found, as it only cuts at around 21khz, keeping most of the frequencies and thus losing little. This probably makes it the best of all the formats to use, and also it allows higher encoding rates than MP2, MP3 and MP4, allowing up to 512kbps whereas the others stop at about 321kbps

WMA 128kbps:

http://members.lycos.co.uk/squirrelo...d/06%20WMA.gif

This is the standard for Windows, and is less lossy than MP2, MP3 and MP4, only cutting at about 18khz, but this is not as good as OGG.

It seems if lossless formats are unavailable due to memory restrictions, then OGG is the best format to use.

compression on audio is the devil unless it's to make meaty overdrives

Thank you Neil - you are precise as always. I will now steal your display and use it to show certain friends of mine the evils of mp3s :D

Kathleen

Re: Audio Compression
 

I could have told you that. :wink:
But thanks for the diagrams.

Actually best ones to use would be lossless ones, flac or shn.

yeah I was gonna say, you dont personally need to analyse all this shit. Shn / flac or nothing !

and if you aint got enough hdd space...get more !

Of course that would be the best options, but not everyone has a hard drive big enough to store it all. I have an 80gb hard drive and even having files as mp2 and mp3 that is already half full, and if I had tried to use flac or shn or something it would have been full long ago.

It's not just hard drive space though, playing such big files is not always good when trying to run lots of programs at once as the songs often pause and skip because they can't load into memory at the same time as all of your programs.

Until now I've ripped all of my CD's to MP2 384kbps to try to keep them as high quality as possible, but now I think I will go back and do them to Ogg instead.

Whats the point in keeping everything on your hd anyway? U make em flacs and share ur stuff, then delete them. As for flacs downloaded, u burn them as audios. Most people do have room for videos, why not for couple of shows as flac? full show as flac takes something around 1GB, IMO that's not too much.

What comes to skipping and such, I think most players can buffer the audio to avoid skipping....or well, just don't run all the progs u got all at once :-p

Well the point of keeping them all on your hard drive (shows and original cd's) is to listen to them. I don't just have audio on my pc to trade with, I listen to it too...don't you?

Also if I tried having each show as FLAC or SHN at around 1gb a show my hard drive would definitely get full fast, as now it is half full just from mp3 stuff (40/80gb).

Well sometimes it's not possible to close lots of program just for the sake of not compressing audio...I have 256mb RAM but if I tried running IE, DC++, WinMX, Overnet, WinAmp and whatever else it wouldn't always play the songs skip free.