My interest in MP3's centres around downloading music files of 1920's music - dance and jazz standards. Naturally, sound quality is not a primary concern. I have a query about MP3 file sizes.
I have downloaded hundreds of tracks from sites such as ‘redhotjazz’ etc (click here)
I play these tracks back via ‘Real Player’ and store these as MP3 files using a Magix program. ie. ‘Audio Cleaning lab 2004’. This works successfully. I transfer these files to CD at the rate of 200 plus files per disc.
The average size of the MP3 is about 2.9 MB.
However, on downloading MP3's from another site, ie click here I notice that the MP3 file size is considerably smaller...approx 860 KB.
Is there a simple explanation for the difference in file sizes. I do not notice any difference in playback quality. However, playback quality is not an issue.
My typical MP3 file size is about the 4mb size thats at a bitrate of about 128kps for a typical song lasting about 4 minutes. Just downloaded one of the files to see, its mono rather than stereo, about a minute shorter and at a bitrate of 40kps. That explains the size difference.
Having had a listen to both websites mirta, the 1st with larger RAM files has recordings of lower quality in the 1st place (hiss & crackles) whereas the 2nd (MP3 downloads) files are slightly better original recordings.
If both were the same, better quality recordings, you probably spot the difference quite easily.
Yet another description of MP3 conversion is: click here This guide is not graphical but does explain the psychoacoustic reason MP3 works with so much compression (around 10:1 or more). A small excerpt from the website says:
"For example, if two notes are very similar and very close together, your brain may perceive only one of them. If two sounds are very different but one is much louder than the other, your brain may never perceive the quieter signal. And of course your ears are more sensitive to some frequencies than others."
So, MP3 cuts out the bits of audio that the compression designers think we can't hear.