Odd behaviours on joining and splitting stereo tracks

[whbjr]

There does seem to be a consensus (at least three votes) on moving Track Info down as that has wider benefits.

Agreed. (or +1 if that's more succinct)

Don't see why it affects making stereo from two mono tracks - that stops as now.

• If it has two mono, it takes the top as left
• If it has left above right, do as now
• If right above left, left moves above right to prevent reversal. It may look odd but that is what user asked for. Don't see why user should have to think in advance and move the R up before making stereo
• If left above left, second left becomes right since user asked for stereo.

+1 for this, as well.

[steve]

There does seem to be a consensus (at least three votes) on moving Track Info down as that has wider benefits.

+1

If you have R above L with L hard panned to left, the panning is broken now IMO

I'm not sure exactly what you mean by "If you have R above L" but I agree that there is a flaw in how "Make Stereo Track" operates. As I see it, the problem is that for two mono tracks there are two pan sliders, but for a stereo track there is (as expected) just one. When the two mono tracks are combined, the positions of the pan sliders on the mono tracks are applied to the audio, but there is no visual indication of panning for the lower (right) channel. The same problem exists with the volume sliders and envelopes. As a conflict may exist between the sliders for the two tracks, the only sensible resolution that comes to mind is that combining two tracks should only be concerned with the track audio. It should not try to adopt other parameters such as pan, gain or envelopes as attempting to do so is doomed to failure in one way or another. If someone wants to apply panning, envelopes or volume levels to one of the tracks before combining with another track they should render the pan before combining the tracks.

I'm -1 about making tracks jump into different orders depending on their original channel allocation. IMO that is unnecessarily confusing as there will be 4 permutations of what may happen rather than just one simple case of the tracks being "stuck together".

[Gale Andrews]

If you have R above L with L hard panned to left, the panning is broken now IMO

I'm not sure exactly what you mean by "If you have R above L"

First track right, second track left.

I agree that there is a flaw in how "Make Stereo Track" operates. As I see it, the problem is that for two mono tracks there are two pan sliders, but for a stereo track there is (as expected) just one. When the two mono tracks are combined, the positions of the pan sliders on the mono tracks are applied to the audio, but there is no visual indication of panning for the lower (right) channel. The same problem exists with the volume sliders and envelopes. As a conflict may exist between the sliders for the two tracks, the only sensible resolution that comes to mind is that combining two tracks should only be concerned with the track audio. It should not try to adopt other parameters such as pan, gain or envelopes as attempting to do so is doomed to failure in one way or another. If someone wants to apply panning, envelopes or volume levels to one of the tracks before combining with another track they should render the pan before combining the tracks.

I'm undecided; I would expect to hear changes when I split and unsplit tracks just as when using the gain on a single track.

It certainly "looks" odd if you have a first track "Left, panned centre" and second "Left, panned hard left" then make stereo that the right is practically silenced which is visible in the meters but not the waveform, all this while the only visible pan slider is at centre. Although it would make Audacity slow, I sometimes think it would be less confusing if there was a preference to render gains, pans and envelopes at once. But this is separate from audibly transposing channels in an unintuitive way I think.

I'm -1 about making tracks jump into different orders depending on their original channel allocation. IMO that is unnecessarily confusing as there will be 4 permutations of what may happen rather than just one simple case of the tracks being "stuck together".

As I predicted ...

The current rule is that the upper split track becomes the left channel when made stereo. The "problem" comes when the right is the upper track and/or the left is the lower AND the tracks have a different mono/left/right property - I think it is these three cases:

1 Right
2 Left

1 Right
2 Mono

1 Mono
2 Left

It isn't easy to put this rule as words, but I am quite sure my ear tells me what we do now with those three cases is quite wrong.



Gale

[Edgar]

I'm a bit confused about Mono/Left & Right. What does the Mono drop-down item do? On a few pieces of audio gear there is a Mono output which sums the Left and Right outputs intelligently so that the output volume is in line with some "average" of Left and Right. I have never seen any other piece of audio gear on which Left and Mono were not the same jack.

Another intuitive confusion is when we try to equate "stereo pan" with "panning a track". Stereo pan is really just a mask for applying negative gain to the channel which is being panned away from. You may prove this by putting two distinctly different signals on Left and Right then listening to the result of a hard stereo pan knob turned back and forth in both directions – the stereo Left and Right signals are not summed – you only hear the one channel. I understand that when we have a number of stereo tracks in a project and we wish to mix them all down to a single stereo track we might want to send both the Left and Right channel of a stereo pair to one side of the mix down so I realize that we must have the Pan control on a stereo track.

[billw58]

A single-channel track that is Mono feeds to the Left and Right outputs equally, unless panned. It behaves like a single-channel strip on a mixing desk.

A single-channel track that is Right or Left feeds to the appropriate output channel. It has no analog on a mixing desk. In this case I'd suggest the Pan slider be greyed or not drawn.

A stereo track feeds to the Left and Right outputs. The Pan slider behaves as Ed describes. Perhaps in this case it should be called/labelled "Balance".
See http://www.behringer.com/EN/Products/UB1204FX-PRO.aspx

As for Make Stereo Track, the rule is simple. The track operated upon becomes the Left channel of the stereo pair and the track below it become the right channel, regardless of any other settings on those tracks. The options in this menu are short-cuts for operating on stereo tracks. If they start respecting Left, Right, Mono, pan and gain settings they lose their attractiveness (speed) as they would then become shortcuts for "mix and render these two tracks". They may be different from what is available in other audio editors, but that is not a bad thing. As long as we properly documents what they do (and perhaps add a couple of use cases as examples) I see no problem with how they operate now.

-- Bill

[steve]

A single-channel track that is Right or Left feeds to the appropriate output channel. It has no analog on a mixing desk. In this case I'd suggest the Pan slider be greyed or not drawn.

Isn't it equivalent to using one side of a stereo channel on a mixing desk?

As for Make Stereo Track, the rule is simple. The track operated upon becomes the Left channel of the stereo pair and the track below it become the right channel, regardless of any other settings on those tracks. The options in this menu are short-cuts for operating on stereo tracks. If they start respecting Left, Right, Mono, pan and gain settings they lose their attractiveness (speed) as they would then become shortcuts for "mix and render these two tracks". They may be different from what is available in other audio editors, but that is not a bad thing. As long as we properly documents what they do (and perhaps add a couple of use cases as examples) I see no problem with how they operate now.

I'm in full agreement.
The ability to split and rejoin stereo tracks is very useful, but it should not be confused with rendering tracks. If the user wishes to take account of envelopes, pan, volume and channel settings we already have a tool specifically designed to do that. Tracks > Mix and Render. If the users wishes to perform an operation on one channel of a stereo track they should split the track, perform the operation and then stick them back together again (Make Stereo Track).

Another intuitive confusion is when we try to equate "stereo pan" with "panning a track".

Panning tracks in Audacity is a bit strange, but I think any further discussion on that subject requires a new topic.

[Gale Andrews]

As for Make Stereo Track, the rule is simple. The track operated upon becomes the Left channel of the stereo pair and the track below it become the right channel, regardless of any other settings on those tracks. The options in this menu are short-cuts for operating on stereo tracks. If they start respecting Left, Right, Mono, pan and gain settings they lose their attractiveness (speed) as they would then become shortcuts for "mix and render these two tracks".

As I suggested, I actually think there is a case for a Preference for gain, pan and envelope to render at once, but I am not suggesting this should happen when you "Make Stereo Track" with R above L, just that Audacity does the extra step of "Move Track Down" on the R track before executing the "Make Stereo Track".

We're campaigning for L and R on the vertical scale (or somewhere) on barely a single case of confusion that anyone can remember, but the "channel reversal" problem in the three scenarios I mentioned does come up on [email protected] and I recall on the -users list too, so I think it is worth discussing (even at the price of making the "Make Stereo" rule "harder to explain"). Clearly the people who get foxed don't see our "simple rule" of "sticking two pieces together" and assume it is already doing something more intelligent when making stereo for L above R.

On a few pieces of audio gear there is a Mono output which sums the Left and Right outputs intelligently so that the output volume is in line with some "average" of Left and Right.

This is in essence what Tracks > Stereo Track to Mono does, but it does render.


Gale

[steve]

the "channel reversal" problem in the three scenarios I mentioned does come up on [email protected] and I recall on the -users list too, so I think it is worth discussing (even at the price of making the "Make Stereo" rule "harder to explain"). Clearly the people who get foxed don't see our "simple rule" of "sticking two pieces together" and assume it is already doing something more intelligent when making stereo for L above R.

Part of the confusion could be because Audacity IS doing something more complex than just sticking the two pieces together and that is with the (mis)handling of the track sliders and envelopes. As I hinted at before I don't think that there is a sensible way for "Make Stereo Track" to take account of track pan and gain sliders without rendering the tracks, but that would just be duplicating the function of "Tracks > Mix and Render" at the loss of simply sticking them together. The only solution that I can see to this issue is for "Make Stereo Track" to ignore the pan and gain sliders and only deal with the audio content of the tracks. Can anyone think of a better solution?

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How to deal correctly with envelopes is more problematic because different envelopes on each channel is partly supported.
I think that the case of retaining envelopes after "Make Stereo Track" is quite strong in that a user may have a stereo track with a complex envelope and a small glitch on one channel that they want to deal with. It should be possible (and currently is) to split the track, make the correction and join the tracks back together without losing the envelope.

The problem arises when two mono tracks with different envelopes are joined together with "Make Stereo Track".
After making a stereo track, each channel shows the envelope that was on the respective mono track. (No problem so far).

Now make a change to the envelope. Depending on whether you adjust the envelope in the left channel or in the right channel the behaviour will be different.
Also, depending on whether you click with the Envelope tool on the edge of the envelope or inside the envelope the behaviour will be different.

I'm not sure what the best way to handle this is, but having such apparently erratic behaviour as there is now is not good.
The situation may change in the future if "track overlays" are adopted (as has been suggested on the developers mailing list), so perhaps we just ignore this problem until we see what these "track overlays" do?
A possible solution would be for the envelope of the upper track to be applied to both channels (both visually and in effect) when making a stereo track?

[Gale Andrews]

the "channel reversal" problem in the three scenarios I mentioned does come up on [email protected] and I recall on the -users list too, so I think it is worth discussing (even at the price of making the "Make Stereo" rule "harder to explain"). Clearly the people who get foxed don't see our "simple rule" of "sticking two pieces together" and assume it is already doing something more intelligent when making stereo for L above R.

Part of the confusion could be because Audacity IS doing something more complex than just sticking the two pieces together and that is with the (mis)handling of the track sliders and envelopes.

No, it's the more basic problem I already outlined of the unexpected channel reversal (without considering the gain/pan complications which just make it worse).

The only solution that I can see to this issue is for "Make Stereo Track" to ignore the pan and gain sliders and only deal with the audio content of the tracks.

It's no solution to the case where they haven't moved the sliders. I see the channel reversal "problem" as more separate than you do.

I think that the case of retaining envelopes after "Make Stereo Track" is quite strong in that a user may have a stereo track with a complex envelope and a small glitch on one channel that they want to deal with. It should be possible (and currently is) to split the track, make the correction and join the tracks back together without losing the envelope.

For sure that should be possible as at least an option.

The problem arises when two mono tracks with different envelopes are joined together with "Make Stereo Track".After making a stereo track, each channel shows the envelope that was on the respective mono track. (No problem so far).
Now make a change to the envelope. Depending on whether you adjust the envelope in the left channel or in the right channel the behaviour will be different.
Also, depending on whether you click with the Envelope tool on the edge of the envelope or inside the envelope the behaviour will be different.

I did not look really carefully but am not sure what you are expecting to happen? That the points on each of the combined channels are not placed at the same amplitude level?

A possible solution would be for the envelope of the upper track to be applied to both channels (both visually and in effect) when making a stereo track?

Kind of goes against "no problem so far" above?


Gale

[steve]

A possible solution would be for the envelope of the upper track to be applied to both channels (both visually and in effect) when making a stereo track?

Kind of goes against "no problem so far" above?

Agreed, but it would be much better than the current behaviour in that the behaviour could be concisely and accurately documented and would be predictable.
The better solution would be for full support for per-channel envelopes but I don't see that happening until track overlays are implemented and that puts it well after 2.0 release.

A demonstration of the issue.
The stereo track shown below was created from two mono tracks using "Make Stereo Track" after adding envelope points to each track.
What do you predict will happen if you click with the Envelope tool at points A, B, C or D?

envelopes.png (23.77 KiB) Viewed 1230 times

After clicking at point A, this is the result (is this what you expected?)
If you now click on the red X, what will happen?
Can this behaviour be unambiguously documented?

envelopes2.png (21.75 KiB) Viewed 1230 times