Loading a track with the exact same speed as the currently running one sometimes results in double speed

[mixxxbot]

Reported by: xeruf
Date: 2018-12-16T15:16:04Z
Status: Confirmed
Importance: High
Launchpad Issue: lp1808697
Attachments: Screenshot_20200518_214240.png

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Sometimes, when I have a track currently playing that has e.g. 100 BPM and load a track with 100 BPM into the other deck while having auto-sync enabled on both decks, the newly loaded track will suddenly be sped up by +100, rarely also slowed down by -50. This is simply annoying and nearly drives me crazy, because when it starts happening it keeps on happening and I have to release auto-sync to manually fix it every time.

I use Mixxx 2.2.0-rc on Linux

[mixxxbot]

Commented by: daschuer
Date: 2018-12-16T21:53:36Z

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What means "will suddenly be sped up by +100"?

+100 BPM? 200%?
Does it start playing with the correct speed? How long does it takes until the track speeds up? Does it stick with +100 or does it go down again?

[mixxxbot]

Commented by: xeruf
Date: 2018-12-16T22:29:21Z

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It speeds up instantly to +100% and keeps at it.

[mixxxbot]

Commented by: daschuer
Date: 2018-12-23T00:58:52Z

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I have managed to see the issue with 2.2 but not with 2.1 and
#1955 merged.

Maybe i have fixed it along with:
https://bugs.launchpad.net/mixxx/+bug/1808698

[mixxxbot]

Commented by: daschuer
Date: 2019-01-13T11:16:02Z

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@xerus Can you confirm that this is fixed now?

[mixxxbot]

Commented by: xeruf
Date: 2019-01-13T19:23:25Z

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Well, it was not 100% reproducible when it happened either, Quite likely that you fixed it with the other bug. We can close and I can reopen if it appears again.

[mixxxbot]

Commented by: daschuer
Date: 2019-01-13T19:32:06Z

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Thank you.

[mixxxbot]

Commented by: xeruf
Date: 2020-05-18T19:44:53Z
Attachments: Screenshot_20200518_214240.png

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It happened again, and when pausing and playing even propagated to the other track - running 2.3.0-alpha-pre!

[mixxxbot]

Commented by: daschuer
Date: 2020-05-18T22:05:28Z

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What exactly did you done step by step and what does Mixxx wrong?
How do you manage to set A to > 100 % rate.

I see how this case is odd, however I don't see anything wrong from your screenshot.

The sync feature calculated the half/double factor by using the file BPM. This is done for a good sound at any slider position.

Your case is this:
A B
Current BMP 210,77 421,54
Rate 100,73 142,27
File BMP 105 174

Since 174 is closer to 210 than to 105, (36 vs 69) the rate at unity A is adjusted to 20 %.
If you now adjust A to 100 rate B becomes 140, which is correct.

Syncing to B to 210 might be expected in this case, but that creates other odd cases in less exceptional cases.

[mixxxbot]

Commented by: xeruf
Date: 2020-05-19T20:16:13Z

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Yeah, it calibrated itself upwards, sort of...
I can't recall the exact steps now, I'll see what I can do...