Re: LP3 hardware Mpeg player

[Rob West <rwest@xxxxxxx>]

Stuart,

The size of a wav file is only dependent on the sample rate, sample
resolution and time (plus the header - but I'll ignore that!) It is not
dependent on the frequencies that are contained in the sound that you've
sampled. For a standard CD the sample rate is fixed at 44.1kHz and the
resolution is fixed at 16 bits - so the size of the wav file for a one
minute track will be the same regardless of whether the track contains
silence, a song ripped from another CD or wav data generated from an
MP3.

A waste of space it may be, but the plus side is that you don't have to
decode a wav file on the fly - you can send the data to a Digital to
Analogue Converter with minimal processing and out pops the sound.

An MP3 to wav conversion won't add white noise back to the sample, but I
suppose you could look at the process as padding out the empty
frequencies with values of zero, rather than just ignoring them as you
do in the MP3.

Hope that helps,

Rob.


Grimshaw Stuart wrote:
>
> I wasn't after reducing the bit rate, but as I understand it, one of
the
> major saving mp3 makes is to remove all the frequencies the human ear
> cannot hear from a wav file, if this is then converted back to a wav
> file, would it pad out these frequencies with "white noise"
or whatever.

--
Rob West                                   +44 (0)1536 201202 Ext.230
Senior Software Engineer                   rwest@xxxxxxx
Intelligent Network Services Ltd.          http://www.insvcs.co.uk

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