[linux-audio-dev] latest news: the editor taketh shape

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Subject: [linux-audio-dev] latest news: the editor taketh shape
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: Mon Oct 23 2000 - 22:50:08 EEST


[ mostly dup'ed from ardour-dev ]

OK, well ardour is all hooked up to a somewhat hacked version of
libgtkwaveform, plus my EDL library. Ardour's main window has been
split into 3 (maybe 2; not sure just yet), and the meter window can be
toggled back and forth to a multitrack editor patterned on a
combination of ProTools, Samplitude and CoolEdit Pro.

At this time, the editor is rudimentary, but it can delete material,
cut-and-paste material, zoom, scroll, solo and mute tracks and put
tracks in and out of "edit groups".

The playback engine continues to be ardour's own, meaning that the
editor can playback essentially arbitary numbers of tracks. Clearly,
the editor and the playback engine share the EDL's for each track, and
any change made in the editor will be reflected in the playback output.

There's a *lot* of miscellaneous work to be done, including:

         * "locate" should jump the editor display to the relevant
             time point.
         * track names/take names need "changed" signals.
         * the editor display should scroll during playback
         * the relationship between "takes" and the editor needs
             to be worked out.
         * EDL history list display widget needed
         * libgtkwaveform support for multiple marks need
         * libgtkwaveform support for signals on select/mark needed
          * etc. etc.
     
One big issue, that I am slowly working on, is the question of x-fades
when doing an insert of some material. I think I am beginning to have
a plausible model worked out. Remember, we're using EDL's here, so its
not as simple as "compute the xfade and overwrite the data".

But the basic framework is now in place for a system that can do most
of the things that any other multitrack editor can, even if there is
some work to get to that point.

**** LADSPA alert ******

I would really like to use a plugin API within the editor. However, as
the discussions here have pointed out, LADSPA is fundamentally
designed around a different premise than the one most suitable for
editing. Ardour is internally capable of doing what David Olofson
mentioned, and hooking up its EDL list to a series of plugins that
would transform the data in real time. But for the most part, this is
inefficient when it comes to things like amplitude envelope shaping
and other fairly "static" edits.

So, I think we need an extension to LADPSA that will allow us to use
any plugins written with it in the context of an editor rather than a
real-time playback engine. If I don't see this as something emerging
soon-ish, I'll just decided to use VST, which will allow such things
via the "batch" model.

--p


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