Mixxx

Pitch Problems using Timecoded Vinyl

Asked by doublue

On Debian, 2.6 64Bit, Mixxx & JACK. Serato CV02
When I try to use real-time vinyl control I get a lag between the rates. I play the same track in software mode (no external control) and hardware (vinyl control). In order to have them playing at the same rate I must pitch up my tables right near +8%. Is this known? I tried adjusting JACK's latency to see if it was some artifact of that but it didn't seem to be. My needles/carts are old, so are my tables.. maybe they're just spinning slow?

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Launchpad Janitor (janitor) said : 		#1

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

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Albert Santoni (gamegod) said : 		#2

Going to answer

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Albert Santoni (gamegod) said : 		#3

Does this problem occur in "relative" or "scratch" mode?

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doublue (mrdoublue) said : 		#4

It seems to be happening regardless of the mode (relative, scratch or absolute).

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Albert Santoni (gamegod) said : 		#5

Can you record into Audacity to check that your signal isn't too loud or too quiet?

This may be an issue with the drift control algorithm that I coded...

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doublue (mrdoublue) said : 		#6

I knew I should have included this earlier... if I plug directly into the computer from the turntable I can't seem to get Vinyl Control to work no matter what setting I use for the Pre-Amp in Mixxx. But I do have an external mixer that I can use. So my signal goes:
TurnTable > Mixer In L\R > HW Fader > HW Fader for Master > Master Out > JACK "System"/Line In

Without the mixer the control just jitters, like tiny back and forward from any location in the audio track.
In order to get any control at all I have to adjust the levels on the hardware mixer. Adjusting the volume there gives interesting behavior. Sometimes it will run backward then stop, sometimes stop, some times jitter in place, sometimes move forward a little (maybe 1 beat) and jitter then move backward.

I'm happy to do everything I can to help, demands will be met! I'm a weeny script kitty, but a sys admin, and I want to help this project however I can.

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doublue (mrdoublue) said : 		#7

I'm not sure of the proper protocol, I don't think I should be responding to the bug report so, I'm adding here. I'm not sure if it will help, but I can route the Hardware inputs through Ardour via JACK which will give me a level of sorts. But that still wont account for the vinyl preamp within Mixxx.

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Albert Santoni (gamegod) said : 		#8

Ok, thanks for the extra info!

I'll try my best to take a look at these issues next week.

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