Project Properties

the essential difference between the project properties dialogue and the preferences dialogue is that preferences are global. If the parameters contained in the project properties dialogue were in the preferences dialogue, if you tried to load a project in a different copy of Reaper with different preferences, the project would be affected, making it very difficult to collaborate on projects etc. This article outlines some, but not all, of the parameters for you, much in the same way as the preferences article. The dialogue is organized into tabs.

Project Settings Tab

This tab is the one that has focus when you first access the dialogue with a fresh copy of Reaper.

"Project Sample Rate": This checkbox dictates whether the sample rate at which Reaper plays audio is dictated by your audio hardware if unchecked or by the settings in this dialogue if checked. This is useful if you wish to handle files at higher sample rates than your hardware can support. Bear in mind though, that your hardware will have to down sample in order to play it to you. Also bear in mind that working at higher sample rates may cause buffer problems. However this setting is configured, remember that any file loaded into a project that does not match the project sample rate will have to be sample converted to the project sample rate by reaper for playback or render.
"Project Sample Rate": If the checkbox discussed above is checked, enter the desired project sample rate here.
"Project BPM": This dictates the musical tempo of your project in beats per minute. Needless to say, adjusting this value will mean that navigating by bar or beat will skip a different amount of time depending on the setting. It will also affect certain tempo-synced effects.
The two edit boxes following "Project BPM" govern time signature. An explanation of time signature is beyond the scope of this article.
"Playback Resample Mode": This combo box dictates the quality at which Reaper converst any files with different sample rates to the project sample rate. Higher quality values are more resource intensive. My personal work flow is to set the playback sample rate to "Better".
"Render Resample Mode": This dictates the quality at which Reaper converts any files at different sample rates to the project sample rate. My personal work flow is to set the render resample mode to extreme, although this can result in significantly longer render times.
"Default Pitch Shift Mode": When adjusting pitch and rate, experiment with different algorithms to see which works best. This can vary depending on the source material.

Media Tab

"Path to save media files. Path can be relative": If you opt to copy or move the media in your project to the project directory, typing a path here will designate a subfolder in your project directory for them.

The remainder of this tab deals largely with the file types and bit-depths you choose for various operations - new recordings, gluing items, freezing tracks etc.

Video Tab

This tab is beyond the scope of this course.

Advanced Tab

"Item Mix Behavior": the options in this combo box dictate how overlapping items behave. I have mine set to "items always mix", which most closely mimics the behavior in Sonar, and means that overlapping items crossfade into one another.
"Track mixing bit-depth": There is no reason to change this setting, however it demonstrates the great precision at which Reaper conducts pre-render, non-destructive processing, i.e. 64-bit floating point.
"Allow Feedback in routing": this means that you can route tracks to themselves using sends.
"Limit Project Length": This checkbox, if checked, will curtail the project at the time specified in the edit box below it.

Notes Tab

This tab simply contains an edit box in which you can write notes about your project, why you did what you did, how you did it, things to remember if you have to stop in the middle of working and a checkbox which dictates whether the notes will be displayed on project load. Notes are an excellent way to facilitate collaboration on projects as well.

Final Notes

Control tab will not navigate between project properties tabs. You can click k the "Save as Default Project Settings" button in any of these tabs. This means that when you create a project, it will appear with the settings that you designated as the default.