Hi Ardour Friends,
I’ve seen this log entry many times, but only today have I heard the audio being affected.
Using 6.0.45, I opened a session and when I started playback all seemed well until the vocals started. They gradually sounding late in time as the song played. Yet, their regions did not move.
The log icon tuned yellow and a great bunch of entries appeared:
Here’s what I got during this session -
2020-06-05T21:38:08 [WARNING]: tempo map was asked for BBT time at sample -8181
2020-06-05T21:38:08 [WARNING]: tempo map was asked for BBT time at sample -4085
2020-06-05T21:38:45 [WARNING]: tempo map was asked for BBT time at sample -8181
2020-06-05T21:38:08 [WARNING]: tempo map was asked for BBT time at sample -4085
2020-06-05T21:38:45 [WARNING]: tempo map was asked for BBT time at sample -8181
2020-06-05T21:38:45 [WARNING]: tempo map was asked for BBT time at sample -4085
Now, for sake of this post, I deleted a lot more of these entries, but here is a short example of what I got.
What does this warning mean and what shall I do about it?
It’s a debug message only logged in debug builds. Optimized builds don’t show this, and unless you’re debugging or developing Ardour, you should probably use an non-debug, optimized binary.
It happens when Ardour needs data from before 00:00:00:00, and tries to look up the corresponding music-time (Bar/Beat/Tick). This is not unusual, and also normal if you have a latent plugin in the session, and start playback at 0.
8181 samples are a lot though. Are you using a buffersize of 4096 (Window > Audio/MIDI setup)?
Gradually? Do you mean as the song progresses the delay increases?
Does it help to start playback at a later time, say near the chorus. Is it in sync?
Hi Robin,
Thank you for helping me with this. Yes, I am doing my part in our Ardour community by choosing to debug. Right now I am only working on personal projects and can afford to do so. I do have the normal v6 version if I need to work on official things.
Also, because I’m working on a Intel i3 laptop, and am only doing mixdowns right now, a high buffer size helps out a lot. So, on a Linux Mint 19 os, I’m running a buffer size of 4096 with 3 periods. This almost completely eliminated x runs for me.
Regarding the varying vocal tracks I’ve experienced, this clears up when I stop, RTZ, and then play again.
PS: The other night I was reading your white paper on latency. That has helped me so much with my sessions. I still have more to read, as at 2AM my brain just needed to stop. Man, did I dream weird after that…
On a lower-end laptop you want to pick the optimized version, particularly for production work.
That often has about half the DSP load compared to debug builds (and only If you do encounter a crash, get a debug build to help investigate).
Ah. That makes sense. Only goto a debug build when trying to recreate an issue. I didn’t know a debug build had that much impact. I will change my process.
