Audacity Forum

cmac185 wrote:FYI, Audacity is not running at home before I go to church so it gets started for the first recording. I've tried leaving it running and just saving and closing the session for the first recording then opening a new session for the second as well as this last week, quiting Audacity (Cmd-Q) after the first recording and restarting it, however it was left started about 45 minutes, but not in record mode, before the second recording started.

Can you try (if you haven't already) COMMAND + Q in Audacity after the first recording, then do not launch Audacity again until you want to record again?

cmac185 wrote:purposely loading up the system with all kinds of stuff running doesn't seem to bother Audacity at all when I'm at home.

One difference is the wireless mic. Does the mic or the receiver support Yosemite?


Gale

cmac185 wrote:
FYI, Audacity is not running at home before I go to church so it gets started for the first recording. I've tried leaving it running and just saving and closing the session for the first recording then opening a new session for the second as well as this last week, quiting Audacity (Cmd-Q) after the first recording and restarting it, however it was left started about 45 minutes, but not in record mode, before the second recording started.


Can you try (if you haven't already) COMMAND + Q in Audacity after the first recording, then do not launch Audacity again until you want to record again?

I haven't tried that yet, will put it on the list.

cmac185 wrote:
purposely loading up the system with all kinds of stuff running doesn't seem to bother Audacity at all when I'm at home.


One difference is the wireless mic. Does the mic or the receiver support Yosemite?

There is no software interface at all with the mic receiver. It is purely an analog system with an analog line-out that plugs into the line-in jack on the laptop.

Cliff

Just an update and maybe a clue to the issue.

Did a recording in parallel this morning.

Using the newly released Audacity 2.1.0 on Yosemite 10.10.2, for the first recording I increased the buffer size from 100 to 200. Bad idea, botched recording almost from the beginning. It still demonstrated the pattern of getting worse over time. Something is getting behind or filling up it seems.

Changed the buffer to 75 for the second recording and all was well.

Both recordings were done with no other programs other than system programs running. Closed down all that could be closed down. Did not reboot, machine had been up 5 days. My main purpose was to prove it was internal to my machine which I did.

The second machine is a year newer and running Mavericks and Audacity 2.0.5. It recorded both times without problems. Buffer size of 100.

Obviously stuff is getting messed up with processing larger batches of data. Any ideas as to what could cause that? Something out of sync?

Just had a crazy idea, could the SSD be too fast and somehow Audacity expects to wait a period of time before starting on the next batch and the write completes too fast? Not likely, but just wanted to throw it out.

Would be an interesting test to increase the priority of Audacity and see if going back to a larger buffer would work.

Cliff

There should be no harm in a buffer setting of 75 if that prevents the problem. Many users on Mac have to reduce that setting.

Gale

Gale,

Thanks for the confirmation.

Is there a way to test for the optimum value? How do I know if 75 maybe is just on the edge of being ok or not? Maybe 50 or 60 would be better. Not knowing what the mechanism of failure is for sure leaves me kind of shooting in the dark. Any guidance on this would be appreciated.

Of course there is still the original puzzle, what about recording at church is different than recording at home seeing that the problem in internal to the computer. The only difference I can see is one is live speech with all it's wide variations in sound and at home it's always been music. Guess I should try recording one of my voice recordings and see it it will mess up with the old buffer setting.

Cliff

Only you can test the "optimum value" but as a suggestion, test with music recordings into line-in at home and set the buffer as low as it will go while still recording the music properly. You can then try keeping that setting for church. If that setting is too low, you can turn it up again - it won't harm the music recording, from what you say.


Gale

Good suggestion, I'll give it a try.

My concern is based on the fact that it seems to be a gradual building up of an issue until it is finally evident in the audio. With the higher buffer setting it reached that point much quicker which makes me think, well if it was ok at 75 great, but previously at 100 it was ok for the first 40 minutes. Then I closed Audacity and restarted it and the second recording was ok at first then went bad as if what ever was getting full or out of sync wasn't in Audacity, but in the system somewhere that wasn't reset by closing Audacity so the second recording continued the problem and reached the audible point shortly into the second recording. Now with the lower setting is the problem solved or will it just take a longer recording time to show up?

I found this interesting item in the release notes:

"(OS X and Linux) PortAudio's default latency values which are used when recording with software playthrough are much lower than Audacity's default "Audio to buffer" setting. This may cause playthrough or recording glitches when recording with software playthrough enabled, especially when using pulse on Linux. Workaround for Linux: record from an (hw) device instead if software playthrough is required."

This is referring to software playthrough, but I wonder if this latency in PortAudio is the key and we somehow need to get in sync with that to keep from the problem all together.

Cliff

You have control over Audacity's buffer setting as long as you don't use Software Playthrough.

If you turn software playthrough on then the buffer is fixed at the (low) PortAudio setting.


Gale

Ok. Is there any way to find out what that setting is? Not that I would necessarily use it, but it might be a useful number to know what it thinks is a good number.

I've been playing with different numbers and got down to 3 just to see if it would do it and it ran for a few minutes and the audio quality seemed ok then Audacity stopped recording it. Had to close Audacity and reopen it again. The recording meter was still indicating, but nothing new was showing on screen. I'm trying 25 right now and letting it run for a couple of hours to make sure it doesn't lock up. That seems pretty low to me. Not sure if I would want to leave it set any lower. What do you think?

Cliff

cmac185 wrote:Is there any way to find out what that setting is?

You can see the low and high PortAudio latency in milliseconds if you open Help > Audio Device Info... and look at the first three numbers after the decimal point.

cmac185 wrote:I'm trying 25 right now and letting it run for a couple of hours to make sure it doesn't lock up. That seems pretty low to me. Not sure if I would want to leave it set any lower. What do you think?

Choose the value that works with your hardware.


Gale