Disable PDC not saving

Is there a way to save a session with Disable PDC enabled in Ardour 6? I can disable PDC in a session and save it but it’s enabled the next time the session is opened.

That is correct and currently intentional behavior.

Why would you want to globally disable it permanently?

I use Ardour as a live mixer for a couple of podcasts. Sending 5 channels with netjack to OBS on another PC to be recorded with the video to avoid sync issues and a few more channels for mix minus for the hosts.

PDC adds delay anytime a netjack source is connected or disconnected and that delay stacks. Disabling PDC usually works but sometimes, not so much.

It’s not a big issue since Ardour 5 has been working flawlessly for years in this setup. I was just curious if that was an option.

Keep up the solid work.

That does not sound right. Netjack is physical I/O. Not related to any plugins.
I/O latency (from your soundcard or netjack) are always compensated for.

When you disable plugin-delay-compensation (PDC), the latency of all plugins is assumed to be zero (instead of the value reported by a latent plugin). If you have any latent plugins in the session, those plugins still introduce a delay, but it is not compensated for by Ardour.

Are you using any latent plugins? A lookahead limiter perhaps?

One guess: Are you using netjack2 (from jack2)? Last I checked that version did not report port latency to the remote side. So in your case OBS cannot correctly align audio/video,
and you only get away because the audio-buffersize and delay is sufficiently small (corresponding to 1-2 video-frames at most).

PS. Can you check with jack_lsp -l on the remote side (OBS), if the netjack ports report capture and playback latencies, corresponding to connected ardour ports plus the network delay?

I am in fact using netjack2 with netone. It does not report port latency to the remote side as you pointed out.

OBS allows the option to buffer audio per track. That’s where any misalignment is sorted out.

Yes, I do use plugins that introduce latency.

Like I said, just curious.

One issue is that the toolbar widget to show/disable PDC is only optionally displayed.

If the setting would be saved with the session and the session is loaded on another system with different UI config it may not be obvious that PDC is disabled.

One workaround is to edit the latency of the given plugin and set it to zero, in the plugin GUI top-left: image. That is saved with the session.

The intended purpose or the button to disable PDC is to quickly allow low latency software monitoring. ie. recording where the path with latent FX is not used, but causes other tracks to be delayed. During Mixing it’s not usually acceptable to disable PDC, since it causes phasing issues. So it should not be a persistent setting.