The How-To (for when close enough isn't good enough)...
First use a loopback test to correct any input offset. Ive included projects that have instructions for this at the bottom.
This may be obvious but just in case, set the buffer as low as you can on your sound card without getting clicks/pops. Its easier to play in time with a lower latency.
For Audio--
Use 'Record Output'(NOT the latency compensated option) on the input track and send its output to another track that has the FX on it.
For MIDI--
In Options>preferences>Media>MIDI, set 'ticks per quarter note' to >>>
Sample Rate * 60 / BPM
eg. Sample rate = 96kHz and BPM = 120 then...
96000*60 = 5760000
5760000/120 = 48000 ticks per quarter note.
This way midi playback and rendering will be sample accurate.
Use 'Record Output(MIDI)' to record the midi. If your vsti doesn't pass the midi through to the track, you can record the midi on a separate track and send it to the track with the vsti on it.
Using the "Preserve PDC..." option is fine timing wise for recording MIDI (but NOT audio) , except the MIDI item will not start on the timeline at the position the cursors was when you hit record, but the notes will be in the correct position.
Using "Preserve PDC..." when recording audio currently still needs to be fixed and i'd like to see it improved by moving the midi/audio within the item instead of the item on the timeline.
Related links...
http://forum.cockos.com/project.php?issueid=842
http://forum.cockos.com/showthread.php?t=116794
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Here's a couple of example track templates that demonstrate the setup described above. One for recording a VSTi and one for recording audio through FX( I've set it up for guitar cause that's what i play, just rename the tracks and change the FX as needed).
Both use plugins included with reaper, just replace them with whatever you like. As described above, they record the output of the internally monitored audio/midi and route that to the track with the FX. Ive put them in folders just for organisation, this doesn't affect the timing in any way.
Ive found using this setup that exactly what you hear during recording is exactly what gets played back after recording.
Enjoy.
