[ardour-dev] testing plugin latency compensation and alignment

[philicorda]

On Mon, 2005-08-01 at 22:50 -0400, Paul Davis wrote:
> > 
> > I did a final test to try and isolate this....
> > 
> > Test 7: Re-recording the recorded exactly in time click track. An
> > artificial latency plugin set to 800ms is inserted on an unused
audio
> > track. Jack period is set to 512 frames.
> > Ardour settings: Align recorded material with existing material.
> 
> how did you go about changing the JACK latency settings? did you exit
> from ardour, or just reconnect it to JACK after restarting JACK?

I can't remember, so I redid the test. Test 3 is
disconnecting/reconnecting rather than restarting Ardour, and gives the
same results as restarting.

Test 1: Re-recording click audio track.
Jack: 2048 frames per period.

Align with existing material  : No plugin            : 190 frames late.
Align with existing material  : 400ms latency plugin : 2240 frames late
Align with existing material  : 2000ms latency plugin: 2240 frames late.
Align with exact time recorded: 400ms latency plugin : 2240 frames late.
Align with exact time recorded: 2000ms latency plugin: 2240 frames late.

Test 2: Re-recording click audio track.
Ardour quit, Jack set to 256 frames per period. Ardour restarted.

Align with existing material  : No plugin             : 190 frames late
Align with existing material  : 400ms latency plugin  : 445 frames late
Align with existing material  : 2000ms latency plugin : 445 frames late
Align with exact time recorded: 400ms latency plugin  : 445 frames late
Align with exact time recorded: 2000ms latency plugin : 445 frames late

Test 3: Re-recording click audio track, disconnecting from jack.
Ardour started with jack at 2048 frames/period 

Align with existing material: 2000ms latency plugin : 2240 frames late

Ardour disconnected from Jack. Jack stopped, set to 256 frames/period,
restarted, Ardour reconnected.

Align with existing material: 2000ms latency plugin : 445 frames late

Is anyone else seeing results like these? If not, I'll try another
soundcard and build a new Jack+Ardour to make sure it's not something
freaky with my particular setup.