Dropouts when recording improvements

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MrRecordMan
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Re: Dropouts when recording improvements

Post by MrRecordMan » Wed Oct 14, 2020 1:53 am

kozikowski wrote:
Wed Oct 14, 2020 1:23 am
Not what I meant. If you do a capture with an error, does the capture's sound file play the error at the same time every time.
Yes, it plays back the same every time and it is visible in the wavefile too. Screenshot here:
Image

I measure it to about 3768 samples, which doesn't seem to hold any relevance to me. Had it been 4096 maybe, but thats too long, and 2048 is too short.
kozikowski wrote:
Wed Oct 14, 2020 1:23 am
https://manual.audacityteam.org/man/dev ... ences.html
Scroll down to Latency > Buffer Length.
Thanks for the link, I've read that, and I understand what a buffer is and how it works, hence my confusion - because it doesn't appear to be doing anything. I have it set at 6 seconds and I'm getting recording and playback almost instantaneously. I can't see/hear the effect of buffer length anywhere.
Is buffer strictly for offline processing?

With regards to my hypothesis about the AC, turns out that's not the culprit. I just started a rip with the AC unit turned off, and I've already gotten two glitches. Could still be another power issue but nothing obvious.
Which turntable?
Tried and true Technics 1200 mk5. I've used this exact turntable to rip hundreds of records into a different setup and she runs like you'd expect - perfectly. To your most recent post, this particular turntable has been internally grounded, for better or for worse.

The glitch is definitely digital, I'm just on a new setup, so I was looking for general advice I might have missed to improve signal flow into this old machine. I will probably try a different surge protector and get a nice power supply anyway to continue to eliminate variables. I'll also try ripping to a different computer. It's frustrating cause nothing seems to make a difference, and it would appear this thing is more than capable, its just that 0.001% failure rate that is killing my rips.

Thanks again

MrRecordMan
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Re: Dropouts when recording improvements

Post by MrRecordMan » Wed Oct 14, 2020 2:04 am

And just to be clear, there's no hum at all. Just a short chunk of digital silence that is very inconsistent and almost impossible to recreate on purpose.

A little background so you know where I'm coming from...
I am in Texas. I've been a DJ for years (I have 7 technics tables, various models), repaired, designed, and manufactured audio electronics, and I write audio software for a living. So feel free to get as technical as you'd like. Also I actually used to do electrician work and I've replaced these outlets - they were backstabbed when I got here but I've connected them properly now. I still wonder if dirty power could be playing a part - the fact that Audacity doesn't detect the dropout tells me its nothing in the computer itself, but I'm definitely not informed on how that dropout detection works.

I'll try to keep this thread updated and I'm still open to any and all suggestions / illumination on my questions regarding audacity's buffer setting and dropout detection.

Thanks yall

kozikowski
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Re: Dropouts when recording improvements

Post by kozikowski » Wed Oct 14, 2020 4:01 am

Technics 1200 mk5.
I did the survo mods for a number of 1200 Mk2 machines (from fuzzy memory). The company posted resistor changes that made the platter not fight you when you were trying to slip-cue. I wouldn't know, but the DJs seemed to like it.
short chunk of digital silence
If you drag-select some of it and Effect > Amplify, what does the panel say? You may get different numbers depending on where the hole is coming from. The analog side may not get any quieter than -70dB or so. The digital connection may come in at -96dB (16-bit limit) and if Audacity is somehow making that damage the panel may look like this.

Screen Shot 2020-10-13 at 8.37.28 PM.png
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Audacity converts everything to 32-bit floating before it does anything. That's to give a super noise floor and an impossible overload/clipping value.

You should put the buffer value back at 100mSec. If you don't, we may be fighting two problems: the original dropout and your wacky setting.

You mentioned you put new memory in. Have you ever done a memory test? Audio software is in a very tiny list of software that uses "high memory." You can do XL spreadsheets and Photoshop edge blur all day long in perfect health, but the instant you run something that takes large bunches of memory, you could touch a bad cell and cause all sorts of troubles.

I have used MemCheck. When I did it, it ran from a floppy to take the smallest footprint possible, and then it would check everything else. Run it all night. It would cycle through many different tests with cutsie names. Checkboard, Flash Ones, running aardvark, rippling dixie, etc. Each one is a different pattern of 1's and 0's written to memory and even if you run it all night, normal, healthy memory should crank through all this without breaking a sweat.

But sometimes:

MEMCHECK - RAMBUNCTIOUS RINO FAILED ON BANK 4 ELEMENT 16 AT 0435 AM.

Koz

MrRecordMan
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Re: Dropouts when recording improvements

Post by MrRecordMan » Wed Oct 14, 2020 5:34 am

kozikowski wrote:
Wed Oct 14, 2020 4:01 am
You mentioned you put new memory in. Have you ever done a memory test? Audio software is in a very tiny list of software that uses "high memory." You can do XL spreadsheets and Photoshop edge blur all day long in perfect health, but the instant you run something that takes large bunches of memory, you could touch a bad cell and cause all sorts of troubles.

I have used MemCheck. When I did it, it ran from a floppy to take the smallest footprint possible, and then it would check everything else. Run it all night. It would cycle through many different tests with cutsie names. Checkboard, Flash Ones, running aardvark, rippling dixie, etc. Each one is a different pattern of 1's and 0's written to memory and even if you run it all night, normal, healthy memory should crank through all this without breaking a sweat.
Thanks for that bit of info. I can't find MemCheck specifically but I found one called MemTest86, I'll try that and see what it says.

So are you saying there might be a different kind of RAM I could try if these tests fail? What would I want to search for?

kozikowski
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Re: Dropouts when recording improvements

Post by kozikowski » Wed Oct 14, 2020 9:02 am

Depending on the OS and version, you may have one built-in. If it fails, then you put in broken memory. Those different tests load in different patterns of data and then check for data addressing, data fade, leakage between cells, leakage between banks, etc. The last time I tried it with a currently available program, the test ran once, dusted off its hands and said "Everything Is Perfect." No, dear, you have to do multiple passes. I haven't built a machine in along time, but that's the idea. You may no longer be able to do that.

What did Effect > Amplify turn up?

You're in the level of testing that assumes normal testing didn't turn up anything and you can't intentionally make it better or worse.

Another testing technique is split the system in half (or fractions) and test each fraction. That gives you the Venn Diagram result.

Screen Shot 2020-10-14 at 1.46.34 AM.png
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The outer balls can be your turntable, your interfaces, and your computer. If you're really having a bad day, only the middle is bad. The combination of your turntable, and your interface, and your computer is needed to produce the damage. Borrow a different computer.

The machine doesn't have Skype or Zoom now. Has it ever?

There are other way-left-field problems possible as well. You're not the only user on your machine. The hole is the Other Entity periodically trying to check in. You can sometimes find those with Desktop > Go > Utilities > Activity Monitor. That's how I once (recently) found a supervisory software licensing program replicating itself and taking up the whole machine. Literally 99% of the memory. I can't tell if that was intentional or not, but it was a wake-up call. Turning over a digital rock.

Koz

MrRecordMan
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Re: Dropouts when recording improvements

Post by MrRecordMan » Wed Oct 14, 2020 2:17 pm

I really appreciate this knowledge you are sharing. Thanks.

First a question, when you say 'high' memory, do you mean 'high density' memory? I've found some online that def has a higher bandwidth than the others, is that what you mean?
If not, what should I be looking for in memory good for large chunks of audio?

kozikowski wrote:
Wed Oct 14, 2020 9:02 am
Depending on the OS and version, you may have one built-in. If it fails, then you put in broken memory. Those different tests load in different patterns of data and then check for data addressing, data fade, leakage between cells, leakage between banks, etc. The last time I tried it with a currently available program, the test ran once, dusted off its hands and said "Everything Is Perfect." No, dear, you have to do multiple passes. I haven't built a machine in along time, but that's the idea. You may no longer be able to do that.
Yea, so the first program I found won't write to usb for some reason, so I found another one called 'Rember', and I'm in the process of running that test 255 times. 5 successful tests so far...

kozikowski wrote:
Wed Oct 14, 2020 9:02 am
What did Effect > Amplify turn up?
Haven't had a glitch again but next time I do I'll turn that up. It really does seem to be pure digital silence, like a glitch in write vs a weak analog connection fizzing out.

kozikowski wrote:
Wed Oct 14, 2020 9:02 am
The outer balls can be your turntable, your interfaces, and your computer. If you're really having a bad day, only the middle is bad. The combination of your turntable, and your interface, and your computer is needed to produce the damage. Borrow a different computer.

The machine doesn't have Skype or Zoom now. Has it ever?
I will try a different computer for sure. This computer is pretty virgin, and dedicated to vinyl. I only have the DJ software (Serato) and audacity, that's basically it.

kozikowski wrote:
Wed Oct 14, 2020 9:02 am
There are other way-left-field problems possible as well. You're not the only user on your machine. The hole is the Other Entity periodically trying to check in. You can sometimes find those with Desktop > Go > Utilities > Activity Monitor.
Yea that's one of the first things I did, but I didn't see any spikes or processes corresponding to the dropouts.

kozikowski
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Re: Dropouts when recording improvements

Post by kozikowski » Wed Oct 14, 2020 4:19 pm

'high' memory, do you mean 'high density' memory?
No. In days gone by, programs could only address memory up to a certain limit. Anything beyond that and the program was expected to start shifting work in and out of the hard drive. This pretty much sucked as you could go to lunch waiting for the hard drive to do anything.

Memory makers could and did start making memory strips larger than the "legacy limit." As that became more popular, different manufacturers "solved it" in different ways. Some designed a protocol for "Expanded Memory" and some had a different system for "Extended Memory." Programmers, of course, got stuck in the middle. I don't remember which one won.

Apps that don't "take a breath" like audio (and video) start using memory just like everybody else, but they don't stop. Several of the Audacity tools need to load the whole performance into memory to work right. This is nothing like calculating a spreadsheet where nobody would know if the app stopped for a split second to shuffle data around. Audio and video run in real time and it's possible they are the only application using memory at the 8GB limit or however much you have.
I'm in the process of running that test 255 times. 5 successful tests so far...
And now you know why we start it when we go to bed. I don't expect this to work, but we are covering the bases. Never dismiss a possibility out of hand.
like a glitch in write vs a weak analog connection fizzing out.
Unless you changed it, the timeline only displays audio between maximum volume (0dB) and about -30dB. Anything quieter than that just turns into a straight blue line. There are ways to fix that, but in my opinion, the fix makes day-to-day editing more difficult.

I pull my bouncing sound meters all the way across the screen (grab bar on the left) and change the quiet end from -60dB to -96dB, the limit of 16-bit audio. That's insanely handy because it lets you look at all sounds likely to be exported at WAV format, whether you can easily hear them or not.

Screen Shot 2020-10-14 at 9.09.39 AM.png
Screen Shot 2020-10-14 at 9.09.39 AM.png (35.3 KiB) Viewed 173 times

Audacity > Preferences > Interface > Meter Range.

Koz

kozikowski
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Re: Dropouts when recording improvements

Post by kozikowski » Wed Oct 14, 2020 4:28 pm

One other idea. There's two ways to get dropouts. You can get the classic dropout where the system stops paying attention to the work. You get a simple hole in the show.

But there's another one where the system has to go potty for a second and picks up exactly where it left off when it gets back. Do the two ends of the gap match? If you sucked out the gap in an edit, would the two remaining ends match?

What happens when you reduce the buffer to a very low number?

Koz

MrRecordMan
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Re: Dropouts when recording improvements

Post by MrRecordMan » Wed Oct 14, 2020 4:37 pm

With all this talk about memory, I'm still not clear what I should be looking for. Could you provide a link to the kind of memory you are talking about?
kozikowski wrote:
Wed Oct 14, 2020 4:28 pm
One other idea. There's two ways to get dropouts. You can get the classic dropout where the system stops paying attention to the work. You get a simple hole in the show.

But there's another one where the system has to go potty for a second and picks up exactly where it left off when it gets back. Do the two ends of the gap match? If you sucked out the gap in an edit, would the two remaining ends match?
No, the ends do not match, it is a silent 'hole' in the recording. Hence why I need to re-record...that audio data is just absent, I can't just delete the space and repair that way, otherwise I would.

I just did the 'amplify' check on it and 'New Peak Amplitude' shows '-infinity', just like your screenshot.

I'll try a buffer of 1ms for this next rip...

MrRecordMan
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Re: Dropouts when recording improvements

Post by MrRecordMan » Wed Oct 14, 2020 4:57 pm

Buffer set to 1ms and no change at all.

I swear I can't tell that buffer length does anything at all.

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