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Author Topic: (Fixed) WDM/loopback suddenly skipping, no obvious cause  (Read 859 times)

Solderman

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(Fixed) WDM/loopback suddenly skipping, no obvious cause
« on: July 28, 2021, 08:45:39 am »

[Odd trouble, but apparently resolved. I leave this as an example of exasperating problems, perhaps to be helpful.]

WDM has suddenly become unusable. It "works" but audio is skipping, like every second or so. Usually I use the WDM feature with web-browser based audio (Pandora, SoundCloud, etc.) Until a few days ago, it worked flawlessly. Now it skips every time. And the problem occurs with local playback too (in my case, tested via VLC video player). It's not the network.

Regular audio playback (e.g. mp3 and FLAC) work perfectly.

It's improbable that MC itself is at fault: not only was the system working fine until a day or two back, but the problem is reproduced using an older release.

Now, before you give me boilerplate advice, allow me to share what I've already done.

In the first place, I'm no novice. I'm 59 years old. I have a BS in Computer Science. I have over 40 years' experience using computers, including Windows PCs for the past 30. I have been a user of MC for many years, since version 23. I don't know everything, but I do know my way around a computer pretty well.

The most important point to note is that NOTHING CHANGED so far as I can tell; this problem suddenly cropped up, with no obvious (or not-so-obvious) cause. Let me repeat that again: the system has been unchanged for many weeks, and suddenly gets the hiccups. Why?

The PC (Pipo X9S 64 GB "disk" (EMMC) and 4 GB RAM) is on the lightweight side. Real time cloud protection is disabled to speed things up.

This set-up was working perfectly for weeks (most recent upgrade was to MC 28 which was done without a hitch.)

No, the PC has NOT had a recent windows or other update before the problem cropped up. I checked. The last windows update was over ten days ago.

I have tried all the usual remedies, to include:

Restart, and power reset all components.

Ran chkdsk /c.

Disk "disk cleanup."

Uninstalled and reinstalled MC (28.0.44) 64 bit.

Uninstalled and reinstalled USB sound interface (MiniDSP driver).

Tried an older version, 28.0.27. Still the same problem.

Trouble -- apparently -- fixed

Remember when I said "nothing had changed?" Well, that's not completely true. About two days ago, I modified my "DSP Studio" settings. I have 8-channel active crossover via MC's settings. On 07-26 I'd added 5 new "adjust a frequency" settings (only three are active, however.) Everything worked fine until 07-28 for some reason, which led to much frustration and me venting my spleen in this trouble report. Well, I thought to myself, why not try the older, saved settings? Poof! The skipping problem went away. Even odder, I then went to the latest, current settings, and now everything is working perfectly.

Problem resolved. Cause: unknown. Guess: something got "hung up," and it was reverting to old DSP settings that reset something.

It's troubleshooting issues like this that make me glad that I'm retired from the IT field. Alas, they will still sometimes plague me.  It's problems like this that sometimes make me regret that I gave up drinking.  >:(
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madbrain

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Re: (Fixed) WDM/loopback suddenly skipping, no obvious cause
« Reply #1 on: August 04, 2021, 02:59:11 am »

FYI, you are not the only one having seen odd things with the WDM driver.
With my audio interface, and old ECHO Audiofire 12, when it's set to output at 96 kHz, there is a whole 0.5 second audio delay in Windows applications that go through the WDM driver. I just tracked this down after having the card for years. I could never use the WDM driver with this delay. When I switched the card to 48 kHz, the whole 0.5 second delay went away with the WDM driver. At least I tracked down the root cause in my case. If you switched something related to frequencies, perhaps the two issues share something in common. 96 kHz setting always works fine within MC itself - major latency issue shows up with WDM driver in the picture.
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Hendrik

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Re: (Fixed) WDM/loopback suddenly skipping, no obvious cause
« Reply #2 on: August 04, 2021, 03:18:47 am »

You should make sure that both the WDM driver and your output are set to the same sample rate, irrespective of what that is. Resampling can have quite a noticeable delay, and by forcing MC to do that, you'll see the delay.
By setting the WDM driver to the same rate as your output, you avoid the delay and everything works much better.
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madbrain

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Re: (Fixed) WDM/loopback suddenly skipping, no obvious cause
« Reply #3 on: August 04, 2021, 04:02:06 pm »

You should make sure that both the WDM driver and your output are set to the same sample rate, irrespective of what that is. Resampling can have quite a noticeable delay, and by forcing MC to do that, you'll see the delay.
By setting the WDM driver to the same rate as your output, you avoid the delay and everything works much better.

Thanks ! That makes sense. And with that advice, I got things to work at 96 kHz without latency. I had set the rate to 96 kHz in my ECHO console for the device, and "convert to 96 kHz" in DSP studio MC. But I never thought to also set it to 96 kHz in the JRiver Windows device. That's 3 places to set it ... It's easy to miss one of them.

Is this documented anywhere ? I was reading the doc at https://wiki.jriver.com/index.php/WDM_Driver and certainly didn't see it. It talks about all the buffers, which I tuned, but nothing about sampling rate. IMO, it deserves to be in the "lipsync" section at least.

I wonder if you could have a way with IPC to automatically set it right. Maybe have the WDM report only report one valid sample rate, the one that's set in MC ? Of course, more than one sample rate may be supported if DSP studio is not set to convert all audio to one sample rate. And someone can make dynamic changes in the GUI after the WDM driver is installed. Sigh. Maybe it's an intractable problem for the general case. But perhaps there could be a default installation that "just works" and guarantees no sampling rate conversion happening in the driver by making / suggesting all those settings changes at the time the WDM driver is installed.

Or have a setting that makes it an error to have a sampling rate conversion happening at the driver level, and pops an error dialog somewhere in MC, so that the user can manually correct the problem with Windows JRiver audio driver settings ? To me that would be way better than having the humongous latency. I thought WDM driver was unusable for years because of this. And it wasn't. The settings were just wrong. The weirdest thing is that it was happening with certain source material and not other, probably because they were recorded at different sampling rates.

It's certainly worthy of more documentation at the very least, even if you leave the program alone entirely, though. But I hope you think about this some more and consider some improvements, whatever they may be.
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