Norns shield glitches in recordings when recording with tape

infinitedigits · 2022-01-30T20:20:21.802Z

Na0s:

It generates little pulses of noise on the meters even when nothing is running (which I think is known to be clock bleed from the LCD driver?)

yes, the old shield (mine is 200323) does have little pulses of noise that peak (very soft…I can only see if I amplify the signal by 30 dB. the noise floor is even lower though).

in contrast - the new shield has a super flat noise floor - no spurious peaks.

here’s a plot:

signal1325×606 163 KB

honestly both are totally fine for me, I only had some trouble with the old shield transients when I was trying to do some onset detection. but (for me) its impossible to actually hear those -30 dB transients.

Na0s:

but additional to that when processing incoming audio I frequently get those same little glitches. It doesn’t seem to be a problem when using a saved audio file and a softcut script so I think my issue, at least, originates at the Input jack?

that’s interesting. does it happen with a particular script or no script at all? some scripts are cpu-intensive and when SuperCollider maxes out it is prone to making sounds that could be called “glitch” sounds or “crunch” sounds. that would be a script-dependent issue I would think though.

SimonKirby:

For what it’s worth, I’ve had a similar issue with my first gen Norns shield with recording line in to tape. No problem on the directly monitored audio, very occasional tiny glitches on the tape recording. I’ve not noticed it on any recordings that aren’t using line in

ah that’s interesting too. I’ve only ever used line-in. but It could be a sampling problem - it sometimes take 15 minutes before I get any glitches (and its still only happening with one particular shield - the newer one actually - and not the other…).

I have a new SD card coming tomorrow so I will try that.

zebra · 2022-01-31T00:29:22.329Z

just to be clear, this thread is now about at least 2 different issues.

Na0s · 2022-01-31T04:28:35.950Z

infinitedigits:

that’s interesting. does it happen with a particular script or no script at all? some scripts are cpu-intensive and when SuperCollider maxes out it is prone to making sounds that could be called “glitch” sounds or “crunch” sounds. that would be a script-dependent issue I would think though.

Unfortunately I don’t have a perfect list or memory. But the only scripts I’ve used enough to be certain I’ve had this issue with are: Barcodes, Granchild, Silos, & Cheat Codes (1&2).

infinitedigits:

yes, the old shield (mine is 200323) does have little pulses of noise that peak (very soft…I can only see if I amplify the signal by 30 dB. the noise floor is even lower though).

Copy that. There were times when I thought I could hear them but looking back on it, it was probably just the other little glitch sounds occurring at the same time as the meters peaked.

zebra · 2022-01-31T06:43:27.354Z

yeah the natural conclusion is that it is probably the sd card (b/c of swapping the roles.)

i would try actually swapping the sd cards as well though. (or equivalently, the shield hardware.) just to eliminate some weird thing in the shield PCB/codec.

i hate SD cards for audio. not even going to get into trying to determine which ones are ok and which are garbage. they are little computers with their own firmware, and sometimes the firmware is just bad. our learning from Aleph was that it is much preferable to work with hardwired storage for realtime I/O.

so, i forgot that i actually did add an overrun check to Tape, but it is ifdef’d out.

github.com

monome/norns/blob/main/crone/src/Tape.h#L166-L172

      
        
            #if 0 
                                std::cerr << "Tape: writer overrun: " 
                                          << bytesAvailable << " bytes available; " 
                                          << bytesToPush << " bytes to push; "
                                          << numFramesCaptured << " frames captured" 
                                          << std::endl;
            #endif

i think that would be the thing to capture and report.

infinitedigits · 2022-01-31T22:35:59.744Z

zebra:

i think that would be the thing to capture and report.

I recompiled with those lines to report tape overruns, but nothing appeared.

I replaced my card on “norns 1” (bought another of the exact same card that is in “norns 2”) and situation has improved. I was getting ~20 glitches / hour. now its ~3 glitches / hour.

1131510×445 33.7 KB

seems like SD card is very likely the culprit and replacement was a decent fix for me.

zebra:

not even going to get into trying to determine which ones are ok and which are garbage. they are little computers with their own firmware, and sometimes the firmware is just bad.

yeah no need! SD cards do seem really finicky - I bought the same exact card (though ~6 months apart) but one still behaves better (no glitches) than the other (very few glitches). weird!

anyways I’m perfectly happy with this solution.

if anyone wants to check their audio files for pops, here’s the super simple python script that made those plots: findpops.py · GitHub

(maybe relevant too: and here’s the super simple python script that can find and excise pops: depop.py · GitHub)

awwaiid · 2022-02-01T00:04:05.499Z

For those two sdcards, here is a doc on u-1 vs u-3. Spoiler - u-3 has 3x faster write speeds.

lapseoftheshutter.com

U3 vs U1 SD Card Ratings: What’s the Difference? – Lapse of the Shutter

vires · 2022-02-06T18:54:29.780Z

Hi! New member here - interesting thread.

I’m considering the purchase of a Norns shield vs regular norns. Is it known if this issue occurs only on the shield? Or since it is looking like sd card issue, is it just as likely to occur on either?

Any advice much appreciated - I’m thankful for this community and ecosystem and glad to be joining it

awwaiid · 2022-02-26T05:28:23.395Z

In this particular case it seems it was the specific sd cards (since swapping them changed behavior more or less). I wouldn’t let this report hold you back from purchasing either based on people generally having an all-around great time with both

zebra · 2022-03-15T21:18:10.129Z

[mod hat] i am moving some posts here, even though they are about playback glitches instead of recording, some of the info above seems potentially helpful.

vires · 2022-03-15T16:43:21.056Z

I am curious if anyone else is having audio dropouts in the tape app.
I’m getting some strange behavior besides the dropouts:
-The loop points (end/beginning of audio file) don’t coincide with where the counter returns to zero. So with each successive pass the minutes:seconds counter is further displaced where the audio file is playing.

-The displacement seems to happen on all included audio files, as well as newly recorded ones. The audio dropout happens on the hermit_leaves.wav at the loop point (which isn’t where the counter indicates it to be, so a little confusing).

-If anyone could confirm this is happening for them or not, I’d really appreciate it as I’m trying to figure out if there’s a problem with mine, if I need to send it in or if it’s an SD card issue

zbs · 2022-03-15T19:26:21.764Z

what is “the tape app”? I wonder if you’re looking for a different thread?

vires · 2022-03-15T19:49:32.654Z

Screen Shot 2022-03-15 at 3.48.01 PM1075×410 61.1 KB

Sorry @zbs - wasn’t sure what to call this. What is the proper terminology for what to call this page/feature of the norns system?

zbs · 2022-03-15T19:57:35.511Z

Nothing to apologize for! that’s usually referred to as the tape page / tape, and it’s persistent no matter what script you’re running. while app/script usually refers to the program you’ve loaded up.
That offset behavior is really weird. I’m still a bit confused though - ~~the tape page doesn’t loop, it just plays back or records one file at a time.~~

edit: nope, i am wrong, sorry. I am clearly too distracted to provide good help so I’ll step back

mei · 2022-03-15T20:10:55.003Z

i’m not on the most recent update yet, but at least on my shield the tape does loop when you play back a file; i thought that was always intended behavior?

@vires i can confirm that on my 2020 diy shield what you’re describing does not happen for me, looping seems fine with no dropouts and the time on the files seem right, to me

zbs · 2022-03-15T20:14:26.102Z

You’re right, sorry about that. I edited my post.

tehn · 2022-03-15T20:25:28.088Z

we’ve identified some sort of issue with the software stack regarding input glitches. we’re working on it and will have something to report/fix soon.

zebra · 2022-03-15T20:44:46.550Z

i assume the reference is to the built in TAPE feature.

i’m not experiencing any dropouts. loop is just a ~~butt-splice of end to start~~ (sorry no, also potentially period of silence for buffering), so easy to get clicks depending how the file is edited. no click for me looping on hermit-leaves. (ah well, that i can notice at least.)
the looping counter drift is actually a known issue (there’s no real hard-sync mechanism, we could add one)
norns/tape.lua at main · monome/norns · GitHub

(we should make it an actual issue if it isnt already i guess. but its a low prio GUI extra in my book.)

indeed we have encountered some new audio glitches in new image, but this doesn’t seem related to me. (i am testing on new image factory norns.)

i think your SD card miiight indeed be an issue, since it seems to happen when the file seeks. (? tho actually idk, i tried to design it such that it will not start looped playback until the streaming buffer is primed; but maybe for slower cards the buffer size would need to be increased.) (and double idk, it would be more expected for SD speed to affect writing than reading.)

i can’t really help further with that except to say there is a lot of info out there aboud SD card xfer speed ratings and etc.

vires · 2022-03-16T02:11:27.583Z

Thanks to everyone for the replies.
It’s a sandisk extreme u3 A1 card, and I tried two of them. I did flash it with I think a pretty old usb sd card reader, not sure if that could cause problems.

@mei - are you sure your counter is working properly? Not sure what to make of that if the drift is a known issue, unless it’s only on some Norns.

If it does end up a known issue on all Norns (or all shields), could be nice to have that in the documentation so users can avoid time spent head-scratching/troubleshooting upon encountering it.

@tehn thats great you identified what’s going on with the input glitches. I didn’t have any, but only did a few 2 minute or so test recordings and afaik these tend to occur on longer recordings.

zebra · 2022-03-16T02:29:14.079Z

vires:

sandisk extreme u3 A1

a brief google search reveals that this is a UHS-1 card, which is the lowest-speed standard with minimum 10MB/s write and 104MB/s read. disk access requirements are super nonlinear but this will for sure stall more often than a UHS-2 or -3 card. (there are some nice links above with more detailed background on SD speeds and standards.)

regarding the position display drift, it is typically insignificant, but we have not put engineerig effort into making it perfect, so it is unlikely to be perfect. (it is just assuming that the actual seconds spent playinfg the file is equal to the elapsed seconds recorded by the system clock.)

the more your card struggles to keep up (introducing buffering time between loops) the faster it will drift.

okey dokey, here is an issue.

mei · 2022-03-16T03:00:29.342Z

i was running a pretty short sample (in the vein of 10-20 seconds) through and i did not notice any discernible drift after about a minute or two, but im sure it could be very different if i let it go longer