Subject: Re: [linux-audio-dev] "pro" soundfile editors for linux
From: Paul Barton-Davis (pbd_AT_op.net)
Date: ma helmi 07 2000 - 22:05:25 EST
>> the key thing is that we consider the raw files immutable most of the
>> time. that is, "non destructive editing" has to mean just that. more
>> than that, things like ardour, which will need to be able to play back
>> the result sometimes need to understand how to read the edit list. so
>
>Here my undo-list approach works better. As the "current situation"
>is always stored in standard audio files, other apps can use them
>directly, but only ecawave can perform undo.
Kai - I can't agree here. I bought 3 18GB drives. Each will hold
roughly the same time duration as the S-VHS tapes used by ADAT
recorders, only at 24tracks/24bits/96kHz (about 40 mins). The
resulting file sizes are enormous (about 700MB per track). If you do
an edit that results in any temporal motion of a sample within the
file, you may have to rewrite up to 100% of the file. That is
*absurd*, especially given that non-destructive editing results on no
rewriting, ever.
As someone else pointed out, all pro editing software uses edit
lists. Moreover, some things cannot be undone. Let me give you an
example of something thats on my mind right now.
With an ADAT recorder, you can specify the crossfade time that is used
when you punch-in and punch-out (start and stop
recording/overdubbing). This varies from about 1 to 50msecs as I
recall. The end result, on the ADAT anyway, is a splice in the data as
any existing recording is faded out and the new stuff fades in. There
is no record of either of the original data streams - just the
resulting mix. I can see no way that you could come back later and
alter the crossfade in such a system - you don't have the original
data to work with.
If you did this with ecasound, it seems to me that you have the same
problem, unless you stash a copy of the 2 original data streams away
somewhere.
To be honest, I can't see a solution to this problem that does *not*
involve making a copy of both the original data stream on the track
and the new stuff for every punch-in, punch-out point. This is true
whether you use an edit list or not. But that point notwithstanding,
this is a case where, presented with just the result of the edit (the
crossfaded mix) and a record of what was done, you cannot back it out
with an undo.
Am I wrong ?
--p
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