LMMS / LMMS/lmms

Delay problem with instruments that are connected through MIDI inputs/outputs

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bug
Dominant language
C++
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Description

Bug Summary

Instruments that are connected through MIDI inputs/outputs won't play at the exact same time.

Steps to reproduce
  1. Put two TripleOscillator instruments in Song Editor
  2. Enable MIDI output on the first instrument
  3. Enable MIDI input on the second instrument
  4. Connect second instrument to first one (through MIDI input, 128:0 LMMS:*Name of the first instrument*)
  5. Put inverter effect on either first or second instrument
  6. Play notes on the first instrument
Expected behavior

Silence.

Actual behavior

No silence, instruments won't cancel each other out.

Detailed bug information

First instrument seems to be playing at the correct time and second doesn't. Also, delay seems to be random.

Affected LMMS versions

LMMS 1.2.2
LMMS 1.3.0-alpha.1.102+g89fc6c9
Probably master as well

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the timing issue in LMMS using two TripleOscillator instruments in Song Editor, MIDI output/input, and an inverter effect as described. Compare the first instrument's timing with the second and investigate the MIDI input/output timing path; done means the instruments cancel correctly and produce silence without random delay.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
audio-video-rtc
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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