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synchronization issue on wav files created by using jack_smf_player and jack_capture

Posted: Mon Apr 03, 2017 5:02 pm
by fujitets
Hi,

I'd like to record .mid file's audio for each instrument, and mix these .wav files.
I'm using jack_smf_player for playing .mid file and jack_capture for recording this audio (using jack-transport start/stop).

But unfortunately these .wav files' tempo is not the same, and not synchronized.
(Of course, I use same tempo setting for these .mid files.)

When I used qtractor for playing each track and jack_capture for recording these audio, each wav file has same tempo and synchronized.

I'd like to know why. Please anyone explain me why.

Re: synchronization issue on wav files created by using jack_smf_player and jack_capture

Posted: Mon Apr 03, 2017 9:28 pm
by rncbc
fujitets wrote:When I used qtractor for playing each track and jack_capture for recording these audio, each wav file has same tempo and synchronized.

I'd like to know why. Please anyone explain me why.
qtractor only takes tempo from first SMF you import into it into a new session.
on all other SMF that you may add later, will get their tempo and time-signature ignored.

you can make that quite evident if you switch the order you import either file first or second time onto an empty new qtractor session.

hth.
cheers

Re: synchronization issue on wav files created by using jack_smf_player and jack_capture

Posted: Sun Apr 09, 2017 6:19 am
by fujitets
you can make that quite evident if you switch the order you import either file first or second time onto an empty new qtractor session.
Thank you for the comment.
When I use qtractor, I use mute/solo control, so there's no problem.

Anyway, maybe I found the solution.
I checked and noticed that all of my processes (such as jackd, linuxsampler, jack_smf_player, jack_capture) have usual priority.
So, I changed these priority to realtime priority 80 (I use "chrt -r 80" for each command), then, recorded wav files are synchronized!!

Thanks.