mike_mccue
It seems like a lot of folks react to requests for Varispeed by offering suggestions or comments about work arounds and different ways to get similar results.
When I read most of these suggestions or comments I get the impression that many people, probably the people who have never used Varispeed, don't seem to understand why, how, or when Varispeed is a great benefit to a musician and their recording technician.
From many of the responses it seems some get it and are offering "workarounds" as you say, but many aren't really getting what you mean by Varispeed as they continue to talk about pitch shifting and fitting to tempo without altering pitch etc.
For those who have never used Varispeed, Varispeed affects BOTH pitch and tempo simultaneously by essentially "doing nothing" to the actual sound except changing the speed of playback which therefore affects the pitch as a result. As such there is little or no stress on the CPU and no odd pitch-shifting artifacts, there is no "processing" involved. Setting aside decades of analog gear, Varispeed has existed in computer-based wave editors since long before audio DAWS even existed. Back when a computer could not play two audio tracks simultaneously or even calculate a "simple" reverb in realtime as it had to be rendered before auditioning, Varispeed functioned just fine.
A good example is Goldwave audio editor, introduced in 1993 which had Varispeed:
http://www.goldwave.ca/about.php In fact, the best "tape slowing to a stop" (or speeding up) I ever heard was using a Varispeed function instead of a pitch-shifting algorhithm. For what it's worth, Goldwave still lists as feature 6 in the Features list as "Variable Speed Playback".
In practice this may be more difficult to adapt to a DAW though. Somehow the engine would have to adapt the Varispeed to the Tempo internally - the DAW cannot continue "thinking" it's playing at 160 BPM when it may now be at 156.23 BPM. Not saying it can't be done but it's not as simple as using Varispeed on a wave file in an editor that is not linked internally to a tempo and therefore possibly VSTi's with dozens of envelopes controlling parameters while they have to compensate with delay-compensation and blah, blah, blah.
So, I'm with you, I could see this being useful, and fun!, but I do question how difficult it might be to implement it in a DAW. I noticed someone claimed Reaper has Vraispeed, but having never used Reaper I have no idea if it uses true Varispeed or whether it affects tempo while maintaing pitch. As others have suggested you could always do a quick mix and throw it in a another program but I realize it's one more unnecessary step you'd prefer to avoid.
Coming from my own selfish perspective, as much as I get you, I'd rather see the issue with third party VST's like Waves , Reaktor - alot of plugins that require more than a standard stereo input pair - dealt with. And the the Staff view tweaked. And then the ability to change the Fader throw height as having a three-inch throw sucks and I don't feel like dragging a controller everywhere (Audition can have the Faders the height of your screen if you like). Etc. etc. Varispeed would probably be a little further down my list than yours, simply based on my own needs.