Audio clicking issue with RODE mic in ProRes

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MCShooter

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Audio clicking issue with RODE mic in ProRes

PostTue Sep 03, 2013 1:50 am

I've noticed a very strange audio issue with Black Magic Camera videos recorded using a Rode NTG-2 as well as a Rode Stereo VideoMic (both straight into camera without preamps). When playing back the original ProRes or an encoded MP4 with AC audio, I notice a small static noise whenever skipping forward or pausing/replaying the video. This happens in all media players, Premiere, all browsers on both Mac and PC.
The issue only occurs with the audio coming from a Rode device in a line-in. I was not able to test with another microphone brand to narrow it down the Channel input.

It is not my camera only because I found the same issue in a different BMCC owner's video.



While the playback is perfect, if you start to skip around or play/pause around 00:12-00:18. This only happens when the mic is directly connected to the camera. The zoom-h1 or the internal mic (which is unusable!!) do not have this problem.

Help!
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Jules Bushell

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Re: Audio clicking issue with RODE mic in ProRes

PostTue Sep 03, 2013 2:42 am

I'm not sure, but I think it's a DC Offset problem with the audio. What firmware are you using? I think firmware 1.2.1 and below have this issue. If it is then good news is that it's easily fixable, for example Adobe Audition has a one button click fix.

Later firmware have fixed this but brought in a whole new set of problems with low pre-amp levels and bass roll off issues etc.

Jules
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MCShooter

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Re: Audio clicking issue with RODE mic in ProRes

PostTue Sep 03, 2013 2:44 am

Jules Bushell wrote:I'm not sure, but I think it's a DC Offset problem with the audio. What firmware are you using? I think firmware 1.2.1 and below have this issue. If it is then good news is that it's easily fixable, for example Adobe Audition has a one button click fix.

Later firmware have fixed this but brought in a whole new set of problems with low pre-amp levels and bass roll off issues etc.

Jules


Is there a way to fix this in Premiere Pro CC? I'd avoid bringing in and out of Audition if possible.

Hmm yes I'm using 1.2.1 because 1.3 dulled the sound from the NTG-2 without preamp by like 80%. I haven't tried 1.4 yet but might do that. Any newly introduced issues in 1.4 ? :roll:
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Re: Audio clicking issue with RODE mic in ProRes

PostTue Sep 03, 2013 3:59 am

I was playing around this evening with my Rode Video Mic Pro using a mini to 1/4" jack. (BMCC MFT 1.4.1)

The levels into the camera were extremely low, even with a 20db gain switch on. On the other hand, my MixPre saw the Rode signal perfectly well with only around 30% to get to an acceptable level. With the Video Mic plugged directly into the BMCC , I had to SHOUT to get any appreciable level. I used the audio meters in my Alphatron EVF as a guide so I had some sense of what was happening.

On line level in at 100%, a pilot tone from my mixer gives -12db. I couldn't get close to that with Mic in from the Rode. I'm not sure what's going on, but I'm surprised that BM is having such problems producing usable audio results. I was aware that the camera didn't have meters when I bought it (one of the reasons I got a $1400 EVF), but the squirrelly way audio works on this camera is distressing. It's a quirky camera, I know! But it's not like BM doesn't have any engineering background or entree into professional video production. C'mon guys....

(BTW, I have no intention of using the Rode Video Mic Pro as a main source of audio, but i was hoping I could use it as a slate mic that didn't stink as bad as the laughably low-fi onboard mic BM puts on its camera. Even shooting MOS, I leave the internal mic off because its principle attribute seems to be in producing an aural headache.)

Blaine Russom

Re: Audio clicking issue with RODE mic in ProRes

PostTue Sep 03, 2013 3:36 pm

MC Shooter.. I ALWAYS have this problem with the audio. I don't have a preamp like others do here because I simply refuse to invest money in one if Blackmagic has the capability to improve audio via firmware in the future. So, this is how I fix the problem:

First, I do all my recordings with the BMCC 1.2 Firmware. Once you have your footage, bring your audio into Soundtrack Pro (I use FCP7) by right clicking on the audio track and "send to>soundtrack pro as audio file".

Once you are in Soundtrack pro, adjust the amplitude to whatever level you need it to be in. Normally I adjust the amplitude by bringing it up +9db. This brings the audio levels to an acceptable level. Then I add a compressor to even out the spikes in dialogue. Once you do that, it should sound much much better.. and the popping sound is fixed. Click File>Save.. and you will see the changes in your FCP timeline.

If there is any noise, you can remove it using the noise print option in Soundtrack pro, but I rarely have this issue for my work.
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Frank Glencairn

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Re: Audio clicking issue with RODE mic in ProRes

PostTue Sep 03, 2013 4:25 pm

Blien wrote:MC Shooter.. I ALWAYS have this problem with the audio. I don't have a preamp like others do here because I simply refuse to invest money in one if Blackmagic has the capability to improve audio via firmware in the future. So, this is how I fix the problem:


That's a misconception.

Preamps on most cameras suck - even on expensive ones like RED - which is no wonder if you look at the price for a good fieldmixer.

That's why you always want a pro preamp/fieldmixer in the game, if you care about audio.

I doubt, that - even if BM got all the audio quirks sorted out in firmware - the audio will be really good, until you have a proper fieldmixer - which is true for most cameras from FS100 to Alexa.
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Blaine Russom

Re: Audio clicking issue with RODE mic in ProRes

PostTue Sep 03, 2013 5:46 pm

I didn't say it wasn't necessary. I just said I wouldn't invest in it. I would rather allocate that money to other resources I need until I have enough money for a proper mixer. The preamp by juiced link and others is nice, but what is needed is something with more functions like a limiter. Because then it can be used for other camera hardware once the BMCC has run its course.

I used camera audio without any additional hardware except specialized mics, for my previous JVC110u and it did a very good job. What that camera needed was a compressor or limiter.. that was the issue with that, but I got around it and did whatever adjustments needed in post.

Anyway so the point I wanted to make was, it wasn't a necessary expense.. its a nice to have.
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MatsHelgesson

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Re: Audio clicking issue with RODE mic in ProRes

PostTue Sep 03, 2013 7:42 pm

MCShooter wrote:I've noticed a very strange audio issue with Black Magic Camera videos recorded using a Rode NTG-2 as well as a Rode Stereo VideoMic (both straight into camera without preamps). When playing back the original ProRes or an encoded MP4 with AC audio, I notice a small static noise whenever skipping forward or pausing/replaying the video. This happens in all media players, Premiere, all browsers on both Mac and PC.
The issue only occurs with the audio coming from a Rode device in a line-in. I was not able to test with another microphone brand to narrow it down the Channel input.

It is not my camera only because I found the same issue in a different BMCC owner's video.



While the playback is perfect, if you start to skip around or play/pause around 00:12-00:18. This only happens when the mic is directly connected to the camera. The zoom-h1 or the internal mic (which is unusable!!) do not have this problem.

Help!


With DC Offset, you'll get that clicky noise, as the soundwave shifts rapidly from (noisefloor)dBFS with no playback to -17 dBFS or where the DC offset occurs. Do check out the file in a sound editing suite of some sort. I just played back your video and analyzed it with Digicheck, which accompanies my audio interface. The large peak at 25 Hz is actually a DC offset much lower in frequency. It's DC (0 Hz), not AC. Hence it'll show up in a spectral analyzer.

You'll remove it by using a high pass EQ set to 20 Hz or so.
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Re: Audio clicking issue with RODE mic in ProRes

PostTue Sep 03, 2013 7:49 pm

paulgolden wrote:(BTW, I have no intention of using the Rode Video Mic Pro as a main source of audio, but i was hoping I could use it as a slate mic that didn't stink as bad as the laughably low-fi onboard mic BM puts on its camera. Even shooting MOS, I leave the internal mic off because its principle attribute seems to be in producing an aural headache.)


My experience with the BMCC EF is that it has quite unusable audio circuitry as a whole, not just the mic :D Utter rubbish. I can't even run VERY HIGH line level signals into it without the sound being ruined in an ocean of noise. Even my Canon 550D beats it in terms of noise performance. Sound has to be recorded to a separate recorder. Fortunately it stays in sync nicely even after 15-20 minutes.
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MCShooter

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Re: Audio clicking issue with RODE mic in ProRes

PostWed Sep 04, 2013 12:39 am

Thanks for all the suggestions. Will try stick to 1.2.1 and try the High Pass filter in Premiere.
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Jules Bushell

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Re: Audio clicking issue with RODE mic in ProRes

PostWed Sep 04, 2013 1:50 am

Or if you have Adobe Audition, in Premiere Pro right click on the audio to open up Audition. Go to menu Favourites->Fix DC Offset.

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Frank Glencairn

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Re: Audio clicking issue with RODE mic in ProRes

PostWed Sep 04, 2013 6:47 am

MatsHelgesson wrote:My experience with the BMCC EF is that it has quite unusable audio circuitry as a whole, not just the mic :D Utter rubbish. I can't even run VERY HIGH line level signals into it without the sound being ruined in an ocean of noise.


Than something goes very wrong - if you feed the BMC a clean, balanced, low noise signal and fix the low end in post, the audio is as good as on any recorder or camera.

If you need a very hot line signal to get something out of the BMC I would look into plugs and adapters first. If they are cabled wrong you get a week signal. You need proper balanced cabling from end-to-end.
A lot of folks with a certain version of the Videomic have this problem.
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Chris Hocking

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Re: Audio clicking issue with RODE mic in ProRes

PostWed Sep 04, 2013 11:53 am

Frank Glencairn wrote:if you feed the BMC a clean, balanced, low noise signal and fix the low end in post, the audio is as good as on any recorder or camera.


Sorry, but I'm gonna call you out on this. If we're talking high end cameras, if I send a feed to an Alexa, the final results are basically perfect, meaning that what I hear in my mixer is exactly the same as what ends up on camera. The Alexa is the gold standard in terms of camera audio quality as far as I'm concerned. Even with the RED ONE/EPIC/Scarlet, the audio is pretty good - not perfect, but it's pretty darn close. If we're talking prosumer cameras, any of the Panasonic or Sony cameras with XLR inputs will seriously out-perform the BMCC in terms of audio performance. You can get USEABLE results with this camera - but not nearly "as good" as even the cheapest prosumer cameras on the market.
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MatsHelgesson

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Re: Audio clicking issue with RODE mic in ProRes

PostWed Sep 04, 2013 5:20 pm

Frank Glencairn wrote:
MatsHelgesson wrote:My experience with the BMCC EF is that it has quite unusable audio circuitry as a whole, not just the mic :D Utter rubbish. I can't even run VERY HIGH line level signals into it without the sound being ruined in an ocean of noise.


Than something goes very wrong - if you feed the BMC a clean, balanced, low noise signal and fix the low end in post, the audio is as good as on any recorder or camera.

If you need a very hot line signal to get something out of the BMC I would look into plugs and adapters first. If they are cabled wrong you get a week signal. You need proper balanced cabling from end-to-end.
A lot of folks with a certain version of the Videomic have this problem.


There's nothing wrong with my equpment. I put out a +19 dBu level sine wave at 0 dBFS, which is roughly 7V peak to peak and had to put the BMCC EF to 100% Line level to get it to reach the top level. Even then, I got a noise floor that was clearly heard at -60 to -70 dB if I remember correctly).

The signal was sent from my RME Fireface UFX and I used balanced cables. The audio interface has a dynamic range of 115 dB unweighted at the outputs. It's utterly silent. I used the same outputs and cables to master a CD recently to a good hard drive recorder.

In my experience, one needs 20 dB or so of headroom when recording dialogue, to avoid sudden peaks when the actors are shouting or laughing loudly. With a noise floor at -65 or so, you'll get 45 dB of s/n ratio, which makes this unit unusable for capturing proper audio with the current (1.41) firmware. Proper audio recorders such as KORG MR1000, Sound Devices 722 and even cheaper disposable gear like Tascam DR100 and Zoom H6 produce decent audio with good s/n ratio.
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Re: Audio clicking issue with RODE mic in ProRes

PostWed Sep 04, 2013 6:34 pm

Chris Hocking wrote:
Sorry, but I'm gonna call you out on this. If we're talking high end cameras, if I send a feed to an Alexa, the final results are basically perfect, meaning that what I hear in my mixer is exactly the same as what ends up on camera. The Alexa is the gold standard in terms of camera audio quality as far as I'm concerned. Even with the RED ONE/EPIC/Scarlet, the audio is pretty good - not perfect, but it's pretty darn close. If we're talking prosumer cameras, any of the Panasonic or Sony cameras with XLR inputs will seriously out-perform the BMCC in terms of audio performance. You can get USEABLE results with this camera - but not nearly "as good" as even the cheapest prosumer cameras on the market.


Chris, what exactly are we talking about?
Bad signal specs, bad inputs, bad frequency response, bad s/n ratio?

The signal is 48 kHz at 24 bit, right? Doesn't sound too shabby in my book.
"Cheapest Prosumer Cameras" like the Sony FS700 feature only 16-bit 48KHz.

Balanced inputs on the big BMC cameras. Not bad ether. Unusual plugs, but same signal quality.

Frequency response: So we have this low end problem, I'm also not happy with it, but an easy fix as demonstrated by Robert.

Signal to noise ratio depends more on your preamps than on the recording part of the camera.
The DR100 has not exactly a stellar s/n ratio, the H6 is a step up from the 4 which had a bad s/n ratio too.

I managed to get audio, that was good enough for primetime TV with just a NTG3/Oktava, a JuicedLink preamp and some tweaking in post out of my BMC.
So if it is good enough for the our super picky QC at the national TV, and the Minister President, it's good enough for me - your personal mileage may vary though.

If you compare a $2000 Dollar camera to a $2500 device like the 722, that does just one thing - audio recording as good as possible, - that's a bit apples and oranges, but you know that.
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