Discussion:
[Ardour-Users] Slice marks makes noise
jonetsu
2018-10-27 20:49:18 UTC
Permalink
Observed in Mixbus32C v5.1

1) Import a wav file of a sine wave.

2) Play the sine wave track. It will sound like an uninterrupted
sine wave from start to finish.

3) Add some slice markers using the 's' key. Do not do any further
operation and processing.

3) Play the track again. At each slice a click is heard.

Shouldn't slice marks be software pointers only and not have any
repercussion at all on the audio ?

Cheers.
Robin Gareus
2018-10-27 21:02:40 UTC
Permalink
Post by jonetsu
Observed in Mixbus32C v5.1
1) Import a wav file of a sine wave.
2) Play the sine wave track. It will sound like an uninterrupted
sine wave from start to finish.
3) Add some slice markers using the 's' key. Do not do any further
operation and processing.
3) Play the track again. At each slice a click is heard.
Shouldn't slice marks be software pointers only and not have any
repercussion at all on the audio ?
They're not "slice marks". You "split" the region in two.

http://manual.ardour.org/editing-and-arranging/create-region-fades-and-crossfades/

See also Session > Properties > Fades
Paul Davis
2018-10-27 21:03:56 UTC
Permalink
Post by jonetsu
Observed in Mixbus32C v5.1
1) Import a wav file of a sine wave.
2) Play the sine wave track. It will sound like an uninterrupted
sine wave from start to finish.
3) Add some slice markers using the 's' key. Do not do any further
operation and processing.
3) Play the track again. At each slice a click is heard.
Shouldn't slice marks be software pointers only and not have any
repercussion at all on the audio ?
by default, ardour adds declicking fade in/fade out curves at the beginning
and end of every region, to prevents clicks at region boundaries.

There is, however, no perfect fade in/fade out curve that can prevent all
clicks, AND these curves necessarily change the gain structure of the ends
of the regions.

You can disable individual region fades by right clicking on a given fade
in/out handle or curve, or disable all of them in one step with Session >
Properties > Fades > Region Fades Active
jonetsu
2018-10-27 21:28:39 UTC
Permalink
On Sat, 27 Oct 2018 17:03:56 -0400
Post by Paul Davis
by default, ardour adds declicking fade in/fade out curves at the
beginning and end of every region, to prevents clicks at region
boundaries.
There is, however, no perfect fade in/fade out curve that can prevent
all clicks, AND these curves necessarily change the gain structure of
the ends of the regions.
You can disable individual region fades by right clicking on a given
fade in/out handle or curve, or disable all of them in one step with
Session > Properties > Fades > Region Fades Active
If there's already a mechanism to lessen the impact of slices,
disabling it does not seem to be a good thing. I tried to add some
fades at the highest zoom level but the slice can still be heard.

The bottom line would be, never slice in the middle of an
instrument (violin) playing solo because that will leave a mark.

In this case it was to copy a part of the region to another audio
track, eg. to mult. What I will do is to re-import the original track.

Next time I'll import the same track twice and slice from one of the two
then discard it afterwards. Importing a track for slicing purposes
only, to mult.

I did slices before although in the context of a full band and as such
no clicks were ever heard from the slice marks that remained.

Thanks to all for the details on this.

By the way, is it possible to copy the level editing done in a region
to another track ?

Cheers.
anahata
2018-10-27 21:44:59 UTC
Permalink
Post by jonetsu
If there's already a mechanism to lessen the impact of slices,
disabling it does not seem to be a good thing.
It lessens the impact in this particular and unusual case, which is a
sine wave.
For many joins of actual music when editing, a short fade make *less* of a
click than an instantaneous switch.
Post by jonetsu
The bottom line would be, never slice in the middle of an
instrument (violin) playing solo because that will leave a mark.
That's generally a good principle for any kind of edit. If you moved the
slice to the transition from one note to another it might be less
audible. Also in general avoid slicing at all unless you really want an edit
at that point...
Post by jonetsu
In this case it was to copy a part of the region to another audio
track, eg. to mult.
Why not copy the whole region, then pull the start and end edges of the
copied region to encompass the part you wanted? No slicing required.
--
Anahata
***@treewind.co.uk -+- http://www.treewind.co.uk
Home: 01535 501017 Mob: 07976 263827
jonetsu
2018-10-27 21:49:28 UTC
Permalink
On Sat, 27 Oct 2018 22:44:59 +0100
Post by anahata
Why not copy the whole region, then pull the start and end edges of
the copied region to encompass the part you wanted? No slicing
required.
That 'sounds' like an excellent suggestion !

Cheers.
jonetsu
2018-10-27 21:50:30 UTC
Permalink
On Sat, 27 Oct 2018 17:28:39 -0400
Post by jonetsu
By the way, is it possible to copy the level editing done in a region
to another track ?
What I meant by that is, to copy the gain editing points. Is it
possible to copy a bunch of them to another track ?
David Kastrup
2018-10-28 11:14:33 UTC
Permalink
Post by jonetsu
On Sat, 27 Oct 2018 17:03:56 -0400
Post by Paul Davis
by default, ardour adds declicking fade in/fade out curves at the
beginning and end of every region, to prevents clicks at region
boundaries.
There is, however, no perfect fade in/fade out curve that can prevent
all clicks, AND these curves necessarily change the gain structure of
the ends of the regions.
You can disable individual region fades by right clicking on a given
fade in/out handle or curve, or disable all of them in one step with
Session > Properties > Fades > Region Fades Active
If there's already a mechanism to lessen the impact of slices,
disabling it does not seem to be a good thing. I tried to add some
fades at the highest zoom level but the slice can still be heard.
You could try to change the kind of cross-fade to "Linear" instead of
the default(?) "Constant Power". The latter is intended for fading
between uncorrelated sound sources.

Could Ardour do this automatically if it detected a fade between tracks
corresponding to a continuing source?
--
David Kastrup
Chris Caudle
2018-10-28 21:32:56 UTC
Permalink
Post by David Kastrup
You could try to change the kind of cross-fade to "Linear" instead of
the default(?) "Constant Power". The latter is intended for fading
between uncorrelated sound sources.
Could Ardour do this automatically if it detected a fade between tracks
corresponding to a continuing source?
That seems to me just one step removed from compilers that attempt to
detect you are compiling a benchmark and produce special case optimized
code for that. By that I mean fading a continuing source is so unusual in
real world editing that writing code to automatically detect that case
would have no real world value, and would only be an improvement in
artificial cases like splitting a sine wave. The more typical cases of
editing different takes together, editing dialog bits together, etc. would
have natural discontinuities requiring a cross-fade, and all the work
wasted trying to make split sine waves sound OK would be no help for the
real world cases.
--
Chris Caudle
Axel 'the C.L.A.' Müller
2018-10-27 21:04:45 UTC
Permalink
On Sat, 27 Oct 2018 16:49:18 -0400
Post by jonetsu
3) Add some slice markers using the 's' key. Do not do any further
operation and processing.
These are no markers but actual cuts. By default short fades are added
to the resulting regions.
Al Thompson
2018-10-27 22:43:40 UTC
Permalink
Are you splicing at a zero crossing? Cutting/splicing at a zero crossing should prevent almost all pops.

----- Reply message -----
From: "jonetsu" <***@teksavvy.com>
To: "ardour-users" <ardour-***@lists.ardour.org>
Subject: [Ardour-Users] Slice marks makes noise
Date: Sat, Oct 27, 2018 5:28 PM

On Sat, 27 Oct 2018 17:03:56 -0400
Post by Paul Davis
by default, ardour adds declicking fade in/fade out curves at the
beginning and end of every region, to prevents clicks at region
boundaries.
There is, however, no perfect fade in/fade out curve that can prevent
all clicks, AND these curves necessarily change the gain structure of
the ends of the regions.
You can disable individual region fades by right clicking on a given
fade in/out handle or curve, or disable all of them in one step with
Session > Properties > Fades > Region Fades Active
If there's already a mechanism to lessen the impact of slices,
disabling it does not seem to be a good thing. I tried to add some
fades at the highest zoom level but the slice can still be heard.

The bottom line would be, never slice in the middle of an
instrument (violin) playing solo because that will leave a mark.

In this case it was to copy a part of the region to another audio
track, eg. to mult. What I will do is to re-import the original track.

Next time I'll import the same track twice and slice from one of the two
then discard it afterwards. Importing a track for slicing purposes
only, to mult.

I did slices before although in the context of a full band and as such
no clicks were ever heard from the slice marks that remained.

Thanks to all for the details on this.

By the way, is it possible to copy the level editing done in a region
to another track ?

Cheers.
jonetsu
2018-10-27 22:45:44 UTC
Permalink
On Sat, 27 Oct 2018 18:43:40 -0400
Post by Al Thompson
Are you splicing at a zero crossing? Cutting/splicing at a zero
crossing should prevent almost all pops.
Thanks, this is an excellent suggestion.

Cheers.
Paul Davis
2018-10-27 23:26:28 UTC
Permalink
Post by Al Thompson
Are you splicing at a zero crossing? Cutting/splicing at a zero crossing
should prevent almost all pops.
Zero crossings are a myth and do not exist in any real-world audio.
jonetsu
2018-10-27 23:33:26 UTC
Permalink
On Sat, 27 Oct 2018 19:26:28 -0400
Post by Paul Davis
Zero crossings are a myth and do not exist in any real-world audio.
There are always DC offsets ?
Will J Godfrey
2018-10-28 08:04:40 UTC
Permalink
On Sat, 27 Oct 2018 19:33:26 -0400
Post by jonetsu
On Sat, 27 Oct 2018 19:26:28 -0400
Post by Paul Davis
Zero crossings are a myth and do not exist in any real-world audio.
There are always DC offsets ?
You just get weaker and weaker oscillations until they become buried in the
noise - as I discovered very many years ago when trying to build an electronic
pulse generator.
--
It wasn't me! (Well actually, it probably was)

... the hard part is not dodging what life throws at you,
but trying to catch the good bits.
Al Thompson
2018-10-28 01:55:14 UTC
Permalink
But they do in a sine wave, which is the example given.
And I don't think I'd day that they don't exist in real-world audio, just that they are so clear cut. (No pun intended)

----- Reply message -----
From: "Paul Davis" <***@linuxaudiosystems.com>
To: "Al Thompson" <***@gmail.com>
Cc: "jonetsu" <***@teksavvy.com>, "ardour-users" <ardour-***@lists.ardour.org>
Subject: [Ardour-Users] Slice marks makes noise
Date: Sat, Oct 27, 2018 7:26 PM

On Sat, Oct 27, 2018 at 6:43 PM Al Thompson <***@gmail.com> wrote:
Are you splicing at a zero crossing?  Cutting/splicing at a zero crossing should prevent almost all pops.

Zero crossings are a myth and do not exist in any real-world audio.
Paul Davis
2018-10-28 17:04:23 UTC
Permalink
Post by Al Thompson
But they do in a sine wave, which is the example given.
They don't exist in the overwhelming majority of sine waves.

A true "zero crossing edit" requires that there is a sample of value zero
where the edit/cut can be applied.

Almost all sine waves will instead have a pair of adjacent samples slightly
and slightly below zero. How "slightly" depends on the sine wave frequency
and the sample rate.

If you cut at one of the adjacent samples, you are actually creating a
discontinuity in the output, the audible impact of which will depend on a
variety of factors. Obviously, the if chosen sample's value is very close
to zero, then the effect will be fairly similar to the "true zero crossing"
case.

Apply this to real world audio, with much more complex signals than a
single frequency sine wave... the results of the "zero crossing edit" not
actually using a zero value are much more likely to be an audible
discontinuity (aka "pop" or "click").

This is why Ardour doesn't bother with attempting to "find a zero
crossing", and instead applies a predictable and controllable fade on each
side of the cut. Even this cannot be guaranteed to work - there is always a
hypothetical pathological case where it fails - but it is much more
reliable than the "zero crossing' woo that somehow made into digital
editing lore some years back.
Adriano Petrosillo
2018-10-29 13:19:02 UTC
Permalink
On Sun, 28 Oct 2018 13:04:23 -0400
Post by Paul Davis
Post by Al Thompson
But they do in a sine wave, which is the example given.
They don't exist in the overwhelming majority of sine waves.
A true "zero crossing edit" requires that there is a sample of value zero
where the edit/cut can be applied.
Almost all sine waves will instead have a pair of adjacent samples slightly
and slightly below zero. How "slightly" depends on the sine wave frequency
and the sample rate.
If you cut at one of the adjacent samples, you are actually creating a
discontinuity in the output, the audible impact of which will depend on a
variety of factors. Obviously, the if chosen sample's value is very close
to zero, then the effect will be fairly similar to the "true zero crossing"
case.
Apply this to real world audio, with much more complex signals than a
single frequency sine wave... the results of the "zero crossing edit" not
actually using a zero value are much more likely to be an audible
discontinuity (aka "pop" or "click").
This is why Ardour doesn't bother with attempting to "find a zero
crossing", and instead applies a predictable and controllable fade on each
side of the cut. Even this cannot be guaranteed to work - there is always a
hypothetical pathological case where it fails - but it is much more
reliable than the "zero crossing' woo that somehow made into digital
editing lore some years back.
Technically, finding the closest value to zero and applying a short fade there could minimise clicks though. The fade will progressively decrease sample values until, while not zero, they will become close to zero, and if they're already close to zero, they will/might be practically inaudible. This *should* be able to decrease the length of the fade required to minimise large value discontinuities. It's academic though. Nobody slices sine waves, and real world fades are usually quite long (because you don't need them to be short, as in, a dozen or two of samples).
--
Adriano Petrosillo <***@gmail.com>
Ralf Mardorf
2018-10-30 06:24:22 UTC
Permalink
Post by Adriano Petrosillo
real world fades are usually quite long (because you don't need them
to be short, as in, a dozen or two of samples).
For many real world audio tasks I migrated to proprietary software. It
for example could be very pleasant to cut several WAVs at the same
location, to just reduce the level of a part of those WAVs, by
selecting the cut parts individual or all together and reducing the
level by moving the mouse.

You might say, that instead of the cuts, you better should use the
fader automation of each individual track or to make them a group and to
use the fader automation of the group to adjust the levels.

Now just imagine that all the WAVs already belong to tracks that belong
to different groups for good reasons and you can't make them a group or
the cuts are at different locations in the time line.

You want inaudible short fades, that short, that they aren't noticeable
(resp. minimal noticeable, if you SOLO listen to a track) e.g. even in
the middle of a hold chord. Neither a noticeable click, nor a
noticeable fade is tolerable.

Also imagine you want to get that without using a preferences menu, to
chose the way the WAV cut works, without the need to add tracks to a
group, if it should be possible and to use automation. You just want to
spend 3 seconds of intuitive editing and than continuing making music.

Don't get me wrong, Ardour is a tool for many real world audio tasks,
too, but not for the kind of music, that needs a lot of creative
editing. This usually is a combination of MIDI and audio recordings and
Ardour anyway isn't an appropriate tool for most kinds of MIDI
recordings.

However, cutting WAVs most of the times is possible without getting an
audible click and with nearly inaudible short fades, at least when using
one or the other proprietary software. I don't know how this works under
the hood.

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