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IDCategoryLast Update
0008048bugs2020-04-24 18:15
Reporteragus.terolAssigned To 
Reproducibilityalways 
Status newResolutionopen 
PlatformGNU/Linux x86_64OSDebianOS Versionsid
Product Version6.0-pre1 
Fixed in Version 
Summary0008048: After calibrating MIDI, audio calibration might be required again
DescriptionOn one hand, when calibrating audio for an USB device the measured latency values vary in each audio engine “stop"-"start" cycle. On the other hand, after calibrating MIDI devices, the audio calibration values are no longer valid, and calibrating audio again arises other measured latency values. It might be related, so that when a MIDI calibration is performed, the audio engine is restarted, invalidating previously measured values.

I do not know if this affects all USB devices, but I think I have read something in the forum about this issue. In my particular case, I can reproduce it with the Focusrite Scarlett 18i20 (1st gen.).

There are two attached images. The first image shows the “Audio/MIDI Setup” window with the measured latency values on the first audio calibration process and the editor window with a (recorded through the cable) metronome click wave perfectly synchronized with the beat line.

The second image shows a second recorded metronome click wave which is not synchronized with the beat line. That was recorded after calibrating MIDI. Since another audio calibration was needed, a second one was performed, and in the image, the “Audio/MIDI Setup” window is showing the new obtained latency values.
Steps To Reproduce    1. Launch Ardour and open (or create) a session.
    2. When “Audio/MIDI Setup” window appears, click on “Calibrate Audio”.
    3. Follow instructions, and when it is calibrated, click on “Use results”. Do not disconnect the cable used for calibration.
    4. Go to “Window” > “Audio Connections”, select “Ardour Misc” tab on “Sources” and “Hardware” tab on “Destinations”, and connect “Click Out” (L) to the hardware output where one edge of the cable used for calibration was connected. NOTE: it should be a hardware output not used as output for the “Master” bus.
    5. Add an audio track, and feed its input with the hardware input where the other edge of the cable used for calibration was connected.
    6. Arm the track, and ensure metronome is enabled, toggle on the record button and click the play button.
    7. Stop after several beats, and see how the metronome click wave is perfectly synchronized with the beat lines.
    8. Go to “Window” > “Audio/MIDI Setup” > “Midi Device Setup” and calibrate any MIDI device.
    9. Record again the metronome click as done in step 6.
Expected: The metronome click wave continues being perfectly synchronized with the beat lines in the second take.
Actually: The metronome click is not correctly synchronized with the beat lines in the second take, making audio calibration is required again.
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agus.terol

2020-04-24 18:15

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Issue History

Date Modified Username Field Change
2020-04-24 18:15 agus.terol New Issue
2020-04-24 18:15 agus.terol File Added: bug1_1_before_midi_calibration.png
2020-04-24 18:15 agus.terol File Added: bug1_2_after_midi_calibration.png