playback stops when I open Safari

[roddy20]

Hello!
a strange problem
playing music with iTunes, its Ok if I don't touch anything
when opening Safari, playback stops and EMU is not available until I replug it
logs attached

EMU error.zip
EMU Error2.zip

[Wouter1]

Hard to tell from the logs.... I'm not sure what is going on on your machine. I see that something is resetting the driver in the 2nd log.
I read that safari is playing silence. Maybe this is related to the problem?

[roddy20]

How can I do more detailed test?
it seems to me, driver was stopped when CPU load exceed some limit and never run again until replug

[Wouter1]

If safari somehow completely locks up the CPU log enough, then the EMU device might run out of its buffer and I think audio will stop then.
Maybe I can see more in your logs but I have no time right now.

[roddy20]

There is no problem of that kind with old official driver (for Lion?)
but it can playback only, no recording, in modern macOS (( recording is very much distorted
with your version recording works Ok

Ok, let me know if more logs or any reports will be needed

[Wouter1]

@roddy20 Can you give the exact OS, what machine (type of mac, year) and how you connect (direct to USB2/3/... or via hub) etc

[roddy20]

@roddy20 Can you give the exact OS, what machine (type of mac, year) and how you connect (direct to USB2/3/... or via hub) etc

MacPro5,1, 2010, direct to USB, I use Sierra 10.12.6 (and I have Big Sur 11.1 it is installed to another drive in order of experiment with key -no_compat_check just for testing)

[Wouter1]

@roddy20 so problems occur on Sierra?
This mac has native USB2 ports so there should not be a compatibility issue.
Strange, people have been using my driver for years a.o, on sierra. Cataline, the currently common version, is already 4 versions further, and being phased out.

So that makes me wonder, have you been using sierra for 4 years now with the EMU and suddenly this driver issue appeared?

Is it possible that Safari somehow got updated to something not excactly compatible with Sierra?

[roddy20]

So that makes me wonder, have you been using sierra for 4 years now with the EMU and suddenly this driver issue appeared?

1. EMU is not the only one device, and I don't use it and your driver full-time 7/24
2. problem is not permanent, it occurs sometimes, once a hour, maybe earlier, maybe later
   "might run out of its buffer" I think it is very close to truth
3. it never happen when Mac is just playing music, always related with higher CPU load

[Wouter1]

@roddy20
@2 the driver buffer size is only enough for a split-second amount of sound. So it does not suggest me what the problem can be. I'm not sure about run times of hours, I usually test up to 10 minutes and do recordings of maybe 20 minutes. But again, there are many users and I never heard this problem
@3. What happens if you start safari right away after boot (so no other sounds produced before that time)? And what if you first start safari and then turn on the EMU?

What version of safari do you have?

[roddy20]

@3. What happens if you start safari right away after boot (so no other sounds produced before that time)? And what if you first start safari and then turn on the EMU?

it will work OK
playback stops when I do something else during playback, I mean something with high CPU requirements
Safari is 12.1.2 (12607.3.10) default for Sierra

[roddy20]

I'm not sure about run times of hours, I usually test up to 10 minutes

I ll try to find a way to reproduce the problem immediately
maybe some kind of Geekbench CPU test with 100% CPU load (?)

[Wouter1]

Ok, it seems you are 100% sure about the 100% CPU.

Yes it's possible in theory, as I suggested, if some process with high priority would eat up all CPU then the EMU would run out of buffer. As I said the driver buffer is tiny, in a matter of a split second the buffer would be empty and playback would stall.

The key is 'high priority'. There should be no high prio process hogging the complete CPU for so long (a split second is very long in terms of CPU cycles). The interrupt handling has priority over normal user processes, but maybe safari is not programmed cleanly, or maybe some other driver does have higher prio and is not being fair.

So, could this be caused by another system extension? Some extension you installed (as part of some software)?

[roddy20]

Problem appears with official old driver too
But it is very rare, and it can restore playback in a second after the error without unplug

About 3rd party kexts and software , I am not sure ... I ll reinstall clean macOS in some days, only macOS + your driver and macOS + official driver and I ll compare the behavior and let you know

[Wouter1]

Maybe you can install osx on a scratch disk, just for testing? I think it can even be a USB stick. Just a fresh OS and then install just the EMU driver.

[Smuteee]

Hi, just my two cents to your interesting discussion. First a very big thank you wouter for your ongoing support and driver, i would happily send you some money for making it possible to still use my beloved emu 404 usb with the various iterations of mac operating systems through the years. I use it for audio playback in apple music/vlc as well as playing vitual instruments (vst/au)in logic/cubase/unify in a quasi life situation with attached midi keyboards. For this application it is essential to have a very small buffer to reduce latency, so that the sound produced has no lag from pressing the keys. if you use cpu demanding vst it can cause the emu or driver to stall (audible crackles ) or stop working (no audio) with buffer settings to low. This behaviour i remember experiencing also with old original drivers from emu back in the day. All of this is well known and explains the problems adressed in this threat. Just for listening and recording/measurement You can set a much bigger and in that regard much more „real time“ safe audio buffer without any performance issues, for example 50ms lag when starting playback is barely noticeable. You can adjust this setting with any serious audio application on the mac. Even some free apps can do it. Sorry for the long post. Thank you, Andi