Values returned by TimeMap_GetMeasureInfo

[DrakeSoft]

Hi,

I have a midi track with the following properties:
Tempo: 120.0 bpm, Time Signature: 4/4 Ticks Per Minute: 115200.0 Ticks Per Micro Second: 1.92 PPQ: 960

Each measure consists of 4 quarter notes.

When I call

  local measure_start_pos = reaper.TimeMap_GetMeasureInfo(0, measure) -- retruns value in QN (Quarter Notes)
  local measure_end_pos = reaper.TimeMap_GetMeasureInfo(0, measure + 1) -- retruns value in QN (Quarter Notes)

I get the following for measure_start_pos and measure_end_po:

Measure: 0 QN:0.0 QN:2.0
Measure: 1 QN:2.0 QN:4.0
Measure: 2 QN:4.0 QN:6.0
Measure: 3 QN:6.0 QN:8.0
Measure: 4 QN:8.0 QN:10.0
Measure: 5 QN:10.0 QN:12.0
Measure: 6 QN:12.0 QN:14.0
Measure: 7 QN:14.0 QN:16.0

I was expecting :

Measure: 0 QN:0.0 QN:4.0
Measure: 1 QN:4.0 QN:8.0
Measure: 2 QN:8.0 QN:12.0

to reflect the four quarter notes per measure. Can anyone explain why measure 1 begins at 2.0 instead of 4.0?
Maybe I am misinterpreting something here.

[DrakeSoft]

From what I can determine. The image below shows the relationship between QN, PPQ and time. But QN seems to be the same as time. Is this correct?

[DrakeSoft]

I notice that if I change the temp to 60 BPM then TimeMap_GetMeasureInfo returns what I would expect:

Measure: 0 Start QN:0.0 End QN:4.0 Project Time from QN: 0.0
Measure: 1 Start QN:4.0 End QN:8.0 Project Time from QN: 1.0
Measure: 2 Start QN:8.0 End QN:12.0 Project Time from QN: 2.0
Measure: 3 Start QN:12.0 End QN:16.0 Project Time from QN: 3.0

[DrakeSoft]

I found the problem:

I had copied the code

 local measure_start_pos = reaper.TimeMap_GetMeasureInfo(0, measure) -- retruns value in QN (Quarter Notes)
  local measure_end_pos = reaper.TimeMap_GetMeasureInfo(0, measure + 1) -- retruns value in QN (Quarter Notes)

from someone else's script, but the function signature is as follows:

number retval, number qn_start, number qn_end, integer timesig_num, integer timesig_denom, number tempo = reaper.TimeMap_GetMeasureInfo(ReaProject proj, integer measure)

The returns multiple values and the retval is not actually the start of measure time in QN, that actually follows in the second value. Retval seems to correspond to the project time and not the QN time. So it should be:

  local retval_0, measure_start_pos, measure_end_pos = reaper.TimeMap_GetMeasureInfo(0, measure)

This gives the expected output for 120 BPM:




and also for 60 BPM: