Corrupt wav files with Zoom H6

[Mitchell Stookey]

I have some audio files from my Zoom H6 that seem corrupt in a bizarre way — I can kind of hear the voices for a split second but they are interrupted by sharp, loud bursts of static that are very rhythmical, like a metronome or something. Has anyone encountered this before and know what is causing the problem? Am I getting wild interference? I was recording with both a boom mic and a lav, and both tracks have this intermittent static. Here are the audio files if you want to take a listen and here what I am talking about:

https://drive.google.com/folderview?...FE&usp=sharing

Is there anything I can do to salvage this audio? Does anyone know where along the chain this file went wrong? Thanks in advance.

[Greg Miller]

Did you hear that noise on your headphones while you were recording?

[Mitchell Stookey]

No, it sounded good through the headphones.

[Bruce Watson]

Originally Posted by Mitchell Stookey

...interrupted by sharp, loud bursts of static that are very rhythmical, like a metronome or something.

Could be RFI from a cell phone. IDK.

[Andrew Smith]

Looks like a file based corruption to me. Attached is an image of the visual of what audio content is in the file. Best to take it up with the manufacturer.

Andrew

[Mitchell Stookey]

The files recorded later in the day at a different location came out perfectly fine, and all other uses have too. We were in the hallway of a University when filming, so I'm not sure if there was some kind of signal we were picking up, but like I said before it wasn't coming through on the headphones at the time.

[Andrew Smith]

Reckon that if it was an interference signal it would look very different as your 'interference' is completely blocking out all other audio for its duration. Hard to know for sure.

Andrew

[Jack Zhang]

Check your card write speed. Corruption tends to happen on a slow card, and at 48khz/24bit, 2 channels alone use up 2mbps so 6 channels would take up almost 7mbps.

Also, better to use SDHC cards since SDXC support is bleeding edge for Zoom at this moment on the H series, (only the H6 supports it) so there may be card compatibility issues.

Avoid Sandisk Ultra, as those cards are notorious for not delivering the advertised write speed.

[Jim Andrada]

I had something like this happen and a Forum member suggested a fix that actually worked.

In my case the problem was a dropped byte here and there, probably because the card wouldn't keep up with the write data rate.

The fix (drumroll) was to look at the damaged file in a basic text editor and add a byte somewhere at the beginning (ahead of the noise). This corrupted the previously good parts and un-corrupted the bad parts and a bunch of cutting between the two did the trick. Of course I was only recording in Stereo so it was easier.

No idea if this is really your problem or not but it sort of sounds the same as my problem so maybe worth a try.

I'm leaving for an appointment now but I'll be happy to give it a try this evening. In the meantime I think if you search my posts you might find the actual advice I got.

[Jim Andrada]

Just looked at the image Andrew posted. Wow - this is a mess. It's so totally regular it surprises me.

[Jim Andrada]

Here's a link to the original thread.

What you have is much worse than what I was dealing with - I only had 6 or 8 hits in a 2 hr recording. Not even sure it's the same issue.

But for what it's worth. Oh yeah - it seems to have been deleting a random byte instead of adding one (but either might work - or not work) that did the trick

http://www.dvinfo.net/forum/all-thin...th-bit-me.html

[Steven Digges]

Were those mics wired or wireless? Was the Zoom on battery power or being powered by the usb port.

I have heard interference like that before but it was coming from dirty power being caused by construction right outside the building. The rate of the pulses was matching the rate of the tool they were using to break up the sidewalk. We ground lifted everything and dropped a Furman in line and it cleaned it up. But I don't see how that could apply to your set up.

Please let us know what you figure out. That is scary considering your cans were clean. If it is a card problem then feeding a camera the line out might have saved you. But I just made a ridiculously long post about how that works.

Kind Regards,

Steve

[Mitchell Stookey]

Thanks everyone for your ideas and suggestions trying to solve this problem. We were using batteries, and 1 track was a Sennheiser MKH-416 shotgun and the other a G3 Lav and both tracks have the same static interruptions.

I opened the wav as text like Jim suggested and it's not simple binary, its a lot of gobbledigook to me, so I wouldn't know where to begin tweaking any of that to make a difference.

[Greg Miller]

I've measured the distance between the first sample in each noise burst. (Not through the entire file, but through several successive bursts near the beginning of the file.

In each case, the distance between the start of the bursts is exactly 65536 samples. That's exactly 2^16. So it appears to be some addressing issue. Whether it was a card failure, failure of the recorder, or what happened, I won't speculate. But this was not noise or interference that infiltrated the recorder and get recorded in any way. It's a data failure for sure.

[Jim Andrada]

I opened it and did the byte tweak and it unfortunately didn't seem to fix it. Like Greg, I was bothered by the regularity of the noise. Unlike Greg I didn't think to count samples

I think the actual block write size for an SD card is supposed to be 512k but a lot only write in 128k blocks.

So I'm wondering if the"noise"/"damage" might be occurring at a rate that would correspond to the writing of actual data blocks - ie X blocks get written correctly, Y blocks get hosed, with regularity which could point to an inability of the card to keep up with the data rate.

Oh well, just speculation