Alphacat wrote:
What's the deal with BPM? How do I configure it so that the playback rate change is universal for all .wav files instead of just having it resize the grid?
Also, please tell me there are track envelopes I can manipulate for volume, pan, FX level & automation, that stuff?
1>
Timestretching in Reaper is a piece of piss.......! 
Hold down the Alt button and drag either edge of your sample to stretch/compress it by the desired amount. If you have dragged the edge of a sample in either direction to loop it, alt-dragging will time stretch the entire looped section.
You can stretch multiple samples by selecting them prior to alt-dragging the edge of any of the samples.
Different timestretching algorithms are available, and can be applied on a sample by sample basis. To do this, select a sample, press F2 and select the desired algorithm from the timestretching/pitchshifting section. You can install extra algorithms by firing up the Reaper installation pack, and selecting ReaPitch + all the algorithms from the plugins selection. Reaper can be installed on top of existing versions without effecting any settings or themes etc.
To make sure the timestretch syncs to the BPM, switch on grid snapping (alt-S). To find out more auto timestretching via BPM, check this link --->
http://forum.cockos.com/showthread.php?t=36572
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Reaper also has a playback speed control (the slider bar at the bottom of the sequencer window next to the BPM box). This functions exactly like the pitch control on a vinyl turntable, so when you slide it up, both the pitch and playback rate go up and vice versa. If you right click on the playback speed slider, you can select an option which preserves the pitch of your samples when you change the playback speed. This causes funky 'higher state of concience' style timestretches!
All of the above can be done on the fly whilst audio is playing! The pitch shifting is also non destructive, so you don't need to worry about fucking up your samples.
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2> Click on the 'Env' button for the sequencer track in question and you will find the volume, panning and mute automation options are available to bring up. tick the box for which ever options you want, and a new automation lane will show in the sequencer.
If a new automation lane doesn't show up, it may be that you've 'collapsed' all the automation for that sequencer track to overlay the track itself instead of appearing in a separate track below it.
For each individual automation lane, left clicking the rightmost button gives you the option to overlay that parameters automation on the original sequencer track, or to use its own sub track.
A quick way of showing all your existing automation lanes is to click on the 'Env' button for the sequencer track in question, then to click on the 'Show All' button. All the active automated parameters will occupy their own automation lane underneath the sequencer track that contains the stuff being automated... (if that makes sense??

)
You can also add automation to the master channel by right clicking in an empty area of the left most window and clicking 'show master track'
(Ctrl-Alt-M) You can automate the playback slider by selecting it from the 'env' list on the master sequencer track. This is separate to any tempo changes ou may have in the project...