Metal sound with Nanoflash?
 

Hi,

very odd behaviour with my Nanoflash..
some of the recorded Material has some strange metal echo in Audio, other material is ok..
Tape Footage is always ok..

recorded with 50mbit HD ... Xl-H1.. old one.. sound output camera over rca.. input in Nanoflash over 3,5mm socket... Audio Source is sometimes Microfone and sometimes Mixer..

thank you...

Hi Philipp-
Does the audio from the headphone jack sound OK? Just trying to determine if the audio problem is caused by analog or digital processing.

Thanks-

Hi Mike.. Thanks for the quick help..

I have to find out.. The last few clips were alright.. I keep you updated..

cheers..

Hi..

Here is an example of what happens..

YouTube - VW Loeffelmann 5008.m4v

Between the 2 Closeups there is a significant difference in sound...
Its like the Sound of the Film Robocop 1 ;)

I would say about 10 percent of the clip have this metal noise..

In my opinion the sound over the Headphones is always ok.. but i had crappy Headphones.. just little ones and lots of noise around me.. but today i will to a test in a quiet room..

It sounds to me like there is a difference in the ambient noise due to change of mic location and ambient sound time change (recorded later, second take, not continuous recording).

There also sounds like there may be more than 1 mic, and that can lead to a "plate" or tunnel sound, a fast single echo.

This is just listening to my MBP. But it sounds like the mic placement was bad.

A shot like that should probably have been done with a shotgun mic on a boom just above talent aiming away from ambient noise, I often have a sound absorbing panel just out of the shot that the mic is aiming at, and more panels to block ambient sound.

Good audio is an art.

Sound Shifts
 

Hi Philipp:
It sounds to me like the digital audio sampling rate is shifting back and fourth. (??) I don't think the differences in microphone placement should make that much of a difference. However, good audio *is* an art. and depending on the characteristics of the mic being used there (looks like it could already be a shotgun in the zeppelin, but who knows ?) you could get a shift in audio quality. Although, I'm hearing a great deal of background noise in the wide angle shots, which could possibly indicate an omni-directional mic use. (???) An omni mic will give you horrible sound shifts if you change from close proximity to a few feet back as well. This example of your audio shift is inconclusive Philipp.

Thanks for the help..

I must also agree.. Good Audio is art.. And doesnt always get the recognition it should.. Sadly... Luckiliy in this case it wasnt necessary to have good Audio.. Its just me who wants to know whats wrong with the Audio.. For Future Projects.. It is definitly not the Mic.. Because the Footage recorded on Tape is ok.. Its just the clips on the Nanoflash, which have this metal sound to it.. just a few. not all of them.

I was wondering if anybody else had this problem ?

Different on Tape
 

Hi Philipp:
Could you put up the footage from tape for a direct comparison ? If you're claiming the audio is different on tape, then I'm really curious to listen to the tape footage.

Hi there..

I exported directly from the Timeline.. One is HDV Codec... The other Nanoflash 50mbit..
Just to make sure there is no further compression on it..

MyDrive - Ihr kostenloser Online-Speicher
usr: Nanoflash@tet20
psw: nanoflash

(case sensitive)

This strange sound is not very often.. I would say.. Every 10th clip or so..

I did actually write about this to the Convergent Design Support a few months ago.. And i got an answer immediately.. very good support.. but Tommy Shell couldnt help me.. I did a lot of editing in the last few months and not much camera and this Sound Error didnt occur again.. I thought the update took care about this so i didnt investigate further..
but it didnt.. I am just posting this to find out if anybody else has this problem.. Its maybe just a human error I am making..

I am recording unbalanced Stereo...

Can't View Second Video
 

Hi Philipp:
Can you post that second video example to Youtube or Vimeo and direct link that ? This website wants to collect my info so they can sell it to someone else. I won't register or give them any of my data just to view a video.

registering shouldnt happen with mydrive..

anyway..here is the footage on vimeo...

tape

nanoflash

cheers..

You definitely have problem on the NanoFlash audio.

It is very obvious now, with the two clips.

What does CD have to say?

You may have a defective unit or there may be a problem with your SDI/HDMI out on your camera.

OOPS I see you are using the RCA audio out to Nano unbalanced in. Have you discussed this with CD?

Can you use audio over HDMI or SDI to test?

hi..

i will get my hands on an ex-3 tomorrow and will do some further testing..

Just tested..Audio over Headphones connected to Nanoflash is always ok..

I'm Hearing Audio Phase Cancellations on the Nano Footage !
 

Hi Philipp:
Yup. You most definitely have a problem with the audio in your Nano Flash unit. I can clearly hear audio channel Phase cancellations ! Uuuhhhh, that's not good my friend. :-( If the problem is intermittent, then this is an even more miserable situation, since if it was constant you could just send back your unit and get it fixed or replaced or whatever they will do for you at Convergent Technology. The fact that it is *intermittent malfunction* **could** indicate a microphone preamp issue or a mixer issue prior to the input on the nano Flash itself. I would return your unit to CD and ask them to check it and see if it meets spec. Also, please try more testing with a different microphone and cable or wireless setup, or do your audio through the camera and take it in embedded into the HD-SDI or HDMI signal. Sorry to learn of your problem. Very irritating for you I'm sure.

Assuming Mark is correct about the phase issue do you have the same source going to each channel or is it from two different mics? Try playing just one of the channels and see if it is correct. Phase errors can creep into the system from several sources. Can you playback the files from the Nano flash and mix them together into a mono signal to see if the problem originates from there or is it only when you get them into the edit system that you have the problem.

Pesky Intermittent Phase Errors
 

Hi Philipp & Daniel:
Correct. Phase cancellations can be introduced at each stage within the chain from microphone, preamp, mixer, recorder, and post production NLE. If the artifact was constant, then it could be quickly identified. Since this tinny sound isn't, then you will have to conduct tests along each stage of the system. Your Nano *may not* be the problem at all, but I've been sitting back here in my chair watching your 2 clips over and over again trying to reason through your chain, and I'm wondering something, but I'm not sure yet. (??)

Philipp could you give us what mic, how it was linked to the recorder, and could you specify if an audio mixer or preamps were being used in the chain *before* the Nano, please ??

hi there.. thank you for taking the time..

Two Setups were used
First one:
Sennheiser ME-66 connected directly to Channel 1 on my XL-H1.. And Recorded to Channel 1 and 2..
So its one Mono Source recorded on both Channels..

Second one:
Wireless Sennheiser EW-100..going to a mixer.. I am not sure which one.. I have to ask.. and then into the camera.. but again only into channel 1.. and again one Mono Source recorded on both channels..

in both cases i had this problem..

Of course your right.. it doesnt mean at all that the error lies with the Nanoflash..Maybe my RCA-Out has something.. Its is not the most reliable or professional way to aquire Audio...

I will find out the type of Mixer tomorrow..

Hi Philip-
Quick question: how are the audio level meters on the nanoFlash during a record? Are the levels, as reported by the nanoFlash, correct, or do they hit the rail?

There could be an issue with our digital audio processing in the nanoFlash or a problem with the audio A/D converter or something alltogether different.

Any additonal info would help us diagnose the problem. We have a Canon XL-H1 in the lab, so we can set up a system and try to replicate tomorrow.

Best-

Hi Philip - I've seen this same phasing issue on HD-SDI audio - so maybe you can rule out your external cabling? (if wired incorrectly with ground switched your two mono channels will be 180 deg out of phase). I think the fault definitely lies within the Nano.

I've listened to my original audio off SD cards from The JVC HM700 and it was fine. The Nano was two frames late and phasing whenever fed dual mono.

I'm hoping the 1.1.154 firmware update which I've just installed will eliminate this. In the meantime if the problem is phasing you should be able to lose it by playing one mono channel only, centered out of your NLE or exporting that way to QT.

Hi John-
So it appears that we may have an time offest between audio channels 1 and 2 as well as time offest with respect to the video. If audio channels 1 and 2 slipped out of sync with respect to each other, than this would cause the phase offset you described.

We should be able to track down this problem quickly (assuming it has not already been fixed). I'll test tomorrow and report back.

Best-

So it appears that we may have an time offest between audio channels 1 and 2 as well as time offest with respect to the video. If audio channels 1 and 2 slipped out of sync with respect to each other, than this would cause the phase offset you described.

We should be able to track down this problem quickly (assuming it has not already been fixed). I'll test tomorrow and report back.

--------------------Mike Schell

Remember I was on the original firmware delivered with the unit. Sometimes a picture is worth a thousand words - the original audio on 3 and 4 and the Nano audio on 1 and 2 - you can see the Nano tacks are out of phase on the waveform whereas the SD card tracks are in phase.

First..

Thanks everybody for the Help.. and also CD for the support over E-Mail and here in the Forum.

I found the solution to my problem.. Now.. Its probably not going to let me look good.. because its an ovious solution.. I was trying to find the Error in the Hardware..
but some of you suggested to listen to the Monotrack in the Editing Suite, which i didnt so far.. And Mono it sounds alright.. Then I linked the 2 Mono Tracks in Final cut to a Stereotrack with ALT-L.. And its fixed.. The Metal Echo is gone..

but what i cant figure out.. About 90 Percent of the clips sound alright, even when the 2 Monotracks are not linked together!! And its just those 10 Percent which have to be fixed inside the editing suite.. But its good to know a Workaround to my problem..

FCP & Mono Sound
 

HI Philipp:
What version of fcp are you using ?

7.0.1 German Version

Are we sure that the 2 separate mics are causing phase problems?

Sometimes recording a shotgun on a boom and a wireless mic on talent can result in phase problems.

Hi John-
This is extremely useful! I think the problem is fixed in our new beta code. We are testing today to confirm. We will look at the audio tracks out of the NLE as well as the audio as played out of the nanoFlash (monitoring on our scope).

I'll report back shortly.

Best-

Philipp, the thing about mono audio is that it is, well, mono. You only need 1 track centered to give you sound out of both speakers (assuming both mono tracks are identical and reading your original post they are). You can trash your second mono track altogether. This will ensure no phasing. Perhaps that is what you are doing in FCP - but your solution sounded strange to me? In most audio applications and NLEs you have a pan control that pans your audio left to right. Use this control to centre the mono track and delete the other alotgether. Do this for everything as the fault could just be less pronounced on some of those clips.

If I read what you did correctly (and I don't use FCP regularly) the problem with what you've done is your audio is still out of phase and when combined back to mono on playback it will start to phase again.

cheers John

Mike if you remember my original post in another thread the problem is more than that. I will do a test with the latest firmware to confirm that it is solved but at least with the JVC 700 video was 3 frames early which resulted in audio being two frames late. If you match video streams on timecode (rather than vision) the audio actually appears to be a frame early. (ie 2-3 = -1) This is not the case. In reality the audio is all two frames late.

So for example on matching video with identical frames
SD card stream : timecode 00:17
CD card stream : timecode 00:14

Audio 2 frames late from Nano compared to SD card. I pointed out in my original post that I couldn't be sure that this was a Nano fault or whether the JVC had a timecode differential between the SDI port and SD cards (does seem unlikely).

I checked the audio in Adobe Soundbooth and the right channel is 6/1000 sec earlier (or 3/500 if you want to simplify). A frame in PAL land is 40/1000 so it is 15% of a single frame.

That's as accurate as I can get with my equipment.

best John

Experiencing the same sound issue
 

Hi

This is my firts post here. I have this "bucket" sound on my recordings also.
I use an EX1 and the NanoFlash. Linked together with a sdi cable. No mixer or external mic. I dont use external mic because i record mostly noise from machines.
I have a clip on YouTube where this error? can be heard clearly.
YouTube - MiniFlex FeedLine press tending performing assembly with Fanuc robots
One clip starts at 0.47 and second clip at 3.46.
I have the latest firmware 1.1.154 and the serial number on the unit is 080930209