MUSC 108. Introduction to Music Technology - Fall 2013

03Lab3 - PPQ time

[Overview [Syllabus]

PPQ times are the time format used in Standard MIDI files. You'll use millisecond times when creating your midterm project. You'll convert millisecond times to PPQ times as one of the final steps in your midterm project when you create the Standard MIDI file.

PPQ is an acronym for Parts Per Quarter note. It is referred to as PPQ or PPQN. A standard PPQ value is 480 which means a quarter note is subdivided into 480 parts. All other notes receive a proportion of 480.

PPQ times are independent of the the tempo. In order to calculate the duration of a PPQ value in milliseconds, you need to know the tempo. This chart shows the PPQ value for different note types based on a quarter note equals 480. Remember, dotted notes are equal to the un-dotted note value plus half of that value. For example, a dotted quarter note is equal in duration to a quarter note plus an eighth note. All PPQ values are integers.

Copy data from 03Lab2

Select and copy all data from 03Lab2. Open 03Lab3 and paste the data into cell A1.

Clear column B and add the label ppq

Select the entire column B by clicking on the letter B above cell B1. Press the Delete key to the right of the Backspace key and the contents of column B should be erased. Change the label to ppq.

A Very Strong Recommendation

Always keep chronological time in column A. That way you'll have a reference back to your score. Conversion to PPQ times is normally one of the last steps done in Excel when creating the Standard MIDI File.

Formula for PPQ times

Put PPQ times in column B using a PPQ value of 480. These are the formulas assuming the first Ms time is in A2.

1. The first PPQ time in B2 is =A2*480/1000, where A2 is the first millisecond time.
2. The second PPQ time in B3 is =(A3-A2)*480/1000;
3. All remaining PPQ times are copied and pasted from the formula used in step 2.

Enter formula for the first PPQ time in B2.

Enter the formula for the second PPQ time in B3.

Copy the B3 formula into B4:B59. You should get these results. Note the PPQ pairs 384 followed by 96. The sum of 384+96 equals 480, the PPQ value of one quarter note at any tempo.

Copy cells B1:E59 and paste them into MIDIDisplay.

Play in MIDIDisplay

Set the Time Base to PPQ. Set the PPQ value to 480.

Click Play. Set the tempo to your liking.

PPQ Experiments

Set the tempo to 60, the PPQ value to 480, and Play. You should hear one note per second.

Set the tempo to 60, the PPQ value to 960, and Play. You should hear two notes per second.
Can you explain why?

Set the tempo to 60, the PPQ value to 3840, and Play. You should hear eight notes per second.
Can you explain why?

Set the tempo to 60, the PPQ value to 240, and Play. You should hear one note every two seconds.
Can you explain why?

Continue with 03Lab4.

[Overview [Syllabus]