[Ardour-Users] click free editing and zero crossings

Simon Wise simonzwise at gmail.com
Wed Jun 2 01:39:37 PDT 2010

Thomas Vecchione wrote:
> Ardour already has that particular function for crossfade editing in in my
> experience much more flexible than anything I have seen in many other
> programs including FCP, but I will check with the video guy here to make
> sure I am remembering correctly;)
> What Paul was describing sounds similar to the basic editing model of
> ReZound, but not quite the same, and more focused on looping.  Would be
> interesting sometime to see.

I took a while to reply so that I could put together a summary of the things I 
think Ardour could borrow from the dialogue I am thinking of, maybe enhancing 
the fade edit dialogue - which would be especially useful making loops or 
editing material like radio broadcasts.

The current fade editor has some of the functions already - the fade-in and 
fade-out curves can be adjusted and there is the ability to audition the fade in 
various ways. This could be combined with the ability to change the length of 
the fade and its position on the timeline, and to move the pieces of audio 
relative to the fade, to make it much more flexible. This is what some video 
editors offer in their dialogue.

Tweaking an edit (or the join of a loop which is really the same problem) is 
done in different circumstances. I am assuming here that the two pieces to be 
joined both continue beyond the fade and have some material that will overlap 
the other piece, ultimately unused.

Sometimes the relative position of the pieces to be joined is fixed. Perhaps 
they are synced to other tracks, perhaps they are two ends of a loop that must 
be a fixed length, perhaps the rhythm of the music has determined their relative 
positions in time.

Sometimes the pieces can be moved relative to each other, maybe they are two 
words in a sentence and part of getting the edit correct is changing the timing 
till the flow of time between the words is right or maybe you are creating a 
loop to provide some continuous audio without any particular rhythm so the 
length is not so important, but the seamlessness of the join is extremely important.

Then in the later case, when the pieces of audio will be moved relative to each 
other, there is the question of what else is moved.

Either you move the audio and maintain its relationship with the rest of the 
track by moving the whole rest of the track with it, or you only move the piece 
of audio, letting it slip under the next piece of audio so the rest of the track 
keeps its existing relationship to the timeline. Both methods are useful.

All these possibilities can be allowed for in an enhanced fade editing dialogue, 
and the model used by video editors is a useful guide because it does just that 
and has been effective part of their workflow for a while. Audio needs are a bit 
different, and the Ardour workflow is the context here so a direct copy wouldn't 
be right, but the general idea is worth a close look.

What I imagine, includes:

1/ extend the display to cover more time so that some of the waveform before and 
after the fade would be visible. How much time, how this would change when the 
fade was modified or moved and so forth are decisions to be made while 
experimenting with usage in an Ardour context. It may be important to be able to 
zoom up to sample accuracy, so very short fade times could be tweaked while the 
join point with the values and slopes of each waveform are visible. How the 
overlapping waveforms are represented is important - different colours? the 
underneath waveform as an outline, the used part solid? Plus in the active fade 
region the resultant waveform could be shown, while the originals are still 
visible and the shape of the fade curves are also available to tweak in the way 
they are now. It is quite important to be able to see the unused part of the 
waveform as well as the used part. The visibility of the different parts is 
addressed to some extent already in the current edit dialogue, but needs some 
thought if more options are available. It might be a good solution to add some 
more switches similar to the Fade Out and Fade In buttons so the display changes 
depending on what you want to tweak - the fade curves, the length and position 
of the fade or moving the incoming and outgoing audio.

2/ the start and end points of the fade could be moved independently by dragging 
within this display, and by suitable keyboard shortcuts. This would not move the 
timeline position of the audio in any way. In the video world the basic unit of 
time is mostly 1 frame, so it is easier to decide on the length of a unit of 
movement, but some shorter and longer moves should be available through the 
keyboard. There would also be some shortcut to change the length of the fade 
while keeping its centre point fixed, this would also change the scale of the 
displayed area.

3/ the fade, with its properties and length intact, should be able to slide 
along in time, leaving the two audio pieces in their place. Perhaps by using a 
scrollbar under the waveform display, or perhaps by dragging the fade area 
(though this seems less sensible to me), certainly by using some keyboard shortcuts.

4/ each of the two pieces of audio should be able to be dragged, and nudged with 
shortcut keys, using each of the two modes for moving audio. There is question 
here about the behaviour if the outgoing piece of audio, the one earlier on the 
timeline, is moved (relative to the fade and incoming audio) using the 'effect 
rest of the track' mode. I think the best choice here is to actually move the 
time of the fade and everything following it in the track, rather than moving 
the piece of audio and everything before it. This allows for a workflow working 
through the edits in a particular track one by one in time order, which is 
reasonably likely if you are using the 'effect the rest of the track' mode.

5/ for convenience add a 'jump to next edit in track' shortcut.

This consideration of the choice between different ways of moving the media is 
exactly what the video editor dialogues address quite carefully.

Currently these actions are all possible within Ardour, but to bring then 
together into a single dialogue could make the workflow for some tasks much 
cleaner and faster.


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