PVSTREAM v1.0

this is the standalone version of the DirectX plugin of the same name.

Usage: not much to it, really! It demonstrates  a putative pvoc plugin framework, and is implemented as
a strange form of MediaPlayer - there are no facilities for saving anything to disk.

No command buttions yet, so everything is controlled from menus.

Open a soundifle via the File menu: only mono files are supported
at present (this ~will~ change ere long!).

You can play this file via the Process->Run menu; 
 set optional looping using the checkbox 'Loop Playback'.

And stop playback using the 'Stop' menu, of course.

[NB there is no 'Close' option; just use 'Open' again to open a new file.]

At this stage the file is being streamed through a complete pvoc;
the volume control works on the analysis data. this is mainly provided to enable 
the amplitude of the analysis data to be trimmed, before resynthesis, as overload can sometimes occur. 
While playing, you can freeze the audio using the 'Freeze' menu; all plugin controls are still 
active. Use 'UnFreeze' to resume playback. This  is not yet a foolproof process - sometimes the phases
get all mixed up when you Unfreeze. Usually flashing Freeze/UnFreeze again clears it.


When not playing a file, you can alter analysis parameters and audio settings, 
from the Settings menu.

Analysis:  sets the FFT size, the overlap size (which must be
 not more than half the FFT size, though I don't trap for this in
the dialog yet) and the window size factor. *1 is what we are used to
in CDP pvoc, * 2 is preferred (the default).

Typical combinations are FFT = 1024, overlap = 160 or 256.

The 160 overlap increases the analysis rate, and is better for pitch
shifting work. If you want to shift really low drum sounds, you may find that the lowest FFT size and the 
lowest overlap size (512:64) actually works best for minimizing smearing, as this gives a high analysis rate
together with a small analysis window.  
But overall, there does not appear yet to be a win-win solution to this problem!

Audio: 
   Select the soundcard device, if a choice is available.

   Set the size of the playback buffers. small is good, except when the
   audio breaks up!  8192 should be comfortable, but is of course high latency.
  I can use 4096 almost all the time on my system (WDM Soundblaster driver).

NB: the underlying internal pvoc latency is set by the overlap size.

During playback, you can see the estimated CPU load in the indicator
at bottom left.



PLUGINS:

In any slot: you can install any of the three  plugins on offer:
EXAG, TRANSP,  ACCU.

Click the Plugin button again to unload it. You can do all this while playing a file.
Plugins are processed in left to right order.
My favourite combination: TRANSP->EXAG->ACCU

NB ACCU will not appear to do very much with sustained sounds. Drum loops and
similar varying material will show off its character. Otherwise, run the audio through TRANSP first,
so you can create dynamic changes.

Each slot has a Bypass switch, so you can turn off the effect 
while processing the sound. You can vary the parameters ad lib with the 
sliders, during playback. 

You can keep the plugins when changing audio settings; they are automatically
reinitialized with the new settings. Similarly you can open a new soundfile 
without closing the plugins.

Richard Dobson, CDP, July 2001
rwd@cableinet.co.uk

