I extrapolated a 16 bit MP3 to 24 bit, when I injected it
into Cubase. But then the audio file was a bit longer than
when I don't extrapolate. And, the audio sounds really bad in
places.

Then, I tried to time stretch the other tracks, to fit an
un-extrapolated MP3, and then IT sounds like ****!

Apparently, this time stretch function doesn't work
well in Cubase LE 4.

Paul <(E-Mail Removed)> wrote:
>
> I extrapolated a 16 bit MP3 to 24 bit, when I injected it
>into Cubase. But then the audio file was a bit longer than
>when I don't extrapolate. And, the audio sounds really bad in
>places.
>
> Then, I tried to time stretch the other tracks, to fit an
>un-extrapolated MP3, and then IT sounds like ****!
>
> Apparently, this time stretch function doesn't work
>well in Cubase LE 4.

Well, time-stretching is inherently never going to sound natural
since you're basically resampling everything and then shifting
all the tones by a factor.

But, time-stretching an MP3-encoded file is going to do that and
on top of that it's going to exaggerate all the MP3 compression
effects substantially.

Lossy compression is not acceptable for any kind of production work,
but if you're going to do stuff like resampling it's even worse than
usual.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Oct 3, 1:16*pm, klu...@panix.com (Scott Dorsey) wrote:
> Paul *<quiller...@gmail.com> wrote:
>
> > * * I extrapolated a 16 bit MP3 to 24 bit, when I injected it
> >into Cubase. *But then the audio file was a bit longer than
> >when I don't extrapolate. *And, the audio sounds really bad in
> >places.
>
> > * * Then, I tried to time stretch the other tracks, to fit an
> >un-extrapolated MP3, and then IT sounds like ****!
>
> > * * Apparently, this time stretch function doesn't work
> >well in Cubase LE 4.
>
> Well, time-stretching is inherently never going to sound natural
> since you're basically resampling everything and then shifting
> all the tones by a factor.
>
> But, time-stretching an MP3-encoded file is going to do that and
> on top of that it's going to exaggerate all the MP3 compression
> effects substantially.
>
> Lossy compression is not acceptable for any kind of production work,
> but if you're going to do stuff like resampling it's even worse than
> usual.
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."


Yeah, tons of aliasing and digital artifacts.

The MP3 was used just to demo ideas, but it's good
to know you cannot resample without severe consequence.

On Sun, 03 Oct 2010 13:03:13 -0700, Paul wrote:

> I extrapolated a 16 bit MP3 to 24 bit, when I injected it into Cubase.
> But then the audio file was a bit longer than when I don't extrapolate.
> And, the audio sounds really bad in places.
>
> Then, I tried to time stretch the other tracks, to fit an
> un-extrapolated MP3, and then IT sounds like ****!
>
> Apparently, this time stretch function doesn't work
> well in Cubase LE 4.

Time stretching is always a bit weird, but there are a few things you can
do in Cubase to improve it. I use Cubase 4, and as far as I can tell this
function is identical in LE4.

There are two ways Cubase does time stretching. In real time, or as an
offline process. You can choose in the preferences which one it will use
by default, and the type of algorithm it will use.
When using the real time time stretching, (called 'warp') you need to
select the appropriate algorithm for the kind of audio for each track.
There are options for 'drums', 'plucked', 'pads' etc. This will make a
huge difference to how good it sounds. There is also an advanced mode
that lets you play with things like variance and grain size to get it
just right.

The other way is as an offline process. You get this by right clicking on
a section of audio and selecting timestretch from the 'process menu'.
This gives you more options to play with for different kinds of audio and
generally sounds better than the real time warp, except in the case of
drums or percussion.

There is a lot of depth and options to play with here, so read the
manual! The defaults are almost always wrong, as they don't know what
kind of audio you are stretching!

They have screwed it up unfortunately though, as the best time stretch
for many purposes was the old 'time bandit' one. This was in Cubase3 but
sadly vanished from version 4 onwards. Now there is just the realtime
warp which is a little buggy and somewhat painful to configure, and the
mpex offline stretch which is very slow, way too clever and sometimes
turns transient material into bubbling noises.

I generally just use the offline stretch, but you can use the realtime
one if you freeze or bounce the track after getting it right.

>
> > * * * Then, I tried to time stretch the other tracks, to fit an
> > un-extrapolated MP3, and then IT sounds like ****!
>
> > * * * Apparently, this time stretch function doesn't work
> > well in Cubase LE 4.
>

see

http://www.dspdimension.com/admin/time-pitch-overview/

Mark