Media player to DAC
 

In article , Mike Scott
wrote:
Jim Lesurf wrote:
In article , Rob
wrote:


That's really why I ask - I think. If there's more than one way to
downsample properly, I'm stuffed.

In principle 'downsampling' should be done 'properly' and will then
lead to a uniquely defined results - even if done in various
algorithmic ways.


That's not so.

Downsampling always involves a reduction in Nyquist frequency. It's
necessary therefore to filter the input to make sure frequencies above
this are sufficiently reduced.

Correct.

That filter can never be perfect, and there will be various tradeoffs,
involving extra loss of top-end, in-band ripple and 'wrap-around'
garbage from insufficient rejection of higher-than-Nyquist signal.

Also correct in practice. But you missed my "in principle" in what I wrote
above. (Which you have snipped away.) And presumbly then failed to
understand why I then went on to discuss how "in practice" will be
different - for reasons like the one you mention.

To remind you, what I wrote that you quoted above was immediately followed
by my saying:

But in practice any downsampling or resampling can produce its own
(needless in theory) alterations that vary with the method used.

Perhaps you failed to read that before leaping in. Pity, as understanding
it would have meant you'd have had no reason to write what you did. :-)

It's all down to what the person doing it thought would be best (by some
arbitrary criterion), and there is no unique or 'right' answer.

It is formally incorrect to say there is no "unique or right answer". The
formally correct and uniquely correct "answer" is to have all the in band
components preserved whilst losing all the out of band ones. This follows
from the sampling theorem, etc. That then represents the uniquely "correct"
answer in terms of information theory.

However, as my previous posting on this did point out (but you snipped and
ignored), in practice you tend to have to accept some level of
imperfection. Albeit very small if the resampling is well done.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Media player to DAC
 

In article , Arny
Krueger
wrote:
"Mike Scott" wrote in
message
Jim Lesurf wrote:
In article , Rob
wrote:


That's really why I ask - I think. If there's more than one way to
downsample properly, I'm stuffed.

In principle 'downsampling' should be done 'properly' and will then
lead to a uniquely defined results - even if done in various
algorithmic ways.

That's not so.

If you are defining "uniquely defined" as being some precise bit
pattern, then I am forced to agree.

The problem arises when the poster snips away a following comment and
ignores the distinction I made quite clearly. But which apparently escaped
his grasp. :-)


If computational resources are highly estensible, it is possible to
product digital filters with very nearly ideal phase and amplitude
characteristics.

Indeed. That is a matter of how much care, effort, and computation time,
the people involved are willing to apply to the process.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Media player to DAC
 

On 09/04/2010 12:10, Arny Krueger wrote:
wrote in message



The Java app looks fine, encoded the wav CD file, but
wouldn't encode the HD or mp3 files. I'm not sure why it
has to encode anything, and I tried it with the
'standardise' (gain and offset correction) on and off.

I haven't tested the Java app on a machine that can play HD files natively.

I've only tested it with 44/16 .wav files on a machine that can only play
44/16 .wav files.


I'd guess and say it doesn't work with anything other than 44/16 wav.

You can convert MP3 files to .wav files a number of different ways that are
accurate. One is to load them into Audacity, and export them as .wav files.
MP3 files can also be accurately saved as .wav files using WinAmp. By
accurate, I mean that the resulting .wav files are represntative of what the
MP3 sounds like when played with a MP3 player.

Dirty little secret - all MP3 files are converted to .wav files during
playback, on-the-fly.


Does no harm. I'll try it some time with Windows - but from what you say
there's more to these Naim tracks than differences in sample rate. So
not much point A/B testing then.

Media player to DAC
 

In article , Michael
Chare scribeth thus
"tony sayer" wrote in message
...
In article , Michael
Chare scribeth thus
"tony sayer" wrote in message
...


Better than CD eh?, so just where do you obtain this from?...
--

There are a number of websites which offer downloads.



Are they really any better?..
--

Depends whether your ears (and hifi) are good enough to tell the difference,

I rather think they'd suffice;)..

and whether you brain appreciates the difference it.

I rather think that may well to .. but perhaps the problem is I listen
to far far too much live stuff these days;)..



--
Tony S