Posted by HP on 05/04/07 00:05

*alan* wrote:

SNIP

> Hi Ken ---- just out of curiosity I did a little test with that
> on-line zamzar conversion.
> I didn't have any wma files, so i converted an mp3 to wma and then
> converted that wma to mp3:

> original mp3 = bit rate 128 kbps, 2.79 MB
> converted to wma = bit rate 128 kbps, 2.95 MB
> wma converted to mp3 = bit rate 64 kbps, 1.38 MB

> Although my ears found it hard to detect a difference, I'd say the
> decrease in bit rate as well as in file size in the conversion from
> wma to mp3 is indicative of SOME kind of loss of quality.

> It'd be interesting to see if the same decrease in bitrate and file
> size would result from using that software referred to above.

> --
> Alan

You might test the converted mp3 format file and see if it is in the
Mp3PRO format, old default mp3 at 128 = Mp3PRO at 64 With a file size
reduction of approx. 50%
the Mp3PRO format will play in most all mp3 players with hardly any
decernable diff from the original 128 format.
WITH the proper decoding codec there isn't supposed to be ANY audible
difference (especially if you are listening with the average
PC speaker setup.

SO: coding in the Mp3PRO format would look like this when comparing
files and file sizes

Mp3PRO original mp3 format
64 bit = 128bit
80 bit = 160bit
96 bit = 192bit

Each iteration would see an average file size reduction in the
neighborhood of 50% from the original.

Now, when converting from one coded format to another, regardless of
the format, I believe that losses will and do occur. Thats the nature
of software conversions of music to digital formats. MANY times
probably Not readily decernable except with a serious ear test with
headphones, and long as you are converting compairable format bitrates.

It is always best to Code the first time in the format of choice from
the original source, that way you can decide the quality vs file size
you wish to live with.

A simple compairison, a standard CD can hold maybe 10 hours of mp3's
at 128bitrate, if the same material was coded in the mp3PRO format you
could get maybe 20 hours worth on the same CD. Where as, if you coded
at 320bitrate maybe 3 to 4 hours ???
Can one really hear the difference musically between 320 and 256???
between the original and 320???
between mp3 and some of the Lossless codecs???

You should really test some formats and bitrates with your own
equiptment and ears to judge what works for you

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