When I shot the drummers, I was using the on-board mic and had the level turned down way low. At the instance where it poped, the audio levels did not peak. Surely this points to a fault with the camera? I've shot similar types of drummer performances many times with the DVX's on-board mic and Ive never had these kind of random pops.... I've had distortion with peaked levels - YES, but never clean audio with no level peaking and then randomly BAM, POP, POP...
Audio Popping/ Cracking???
- Thread starter keentave
- Start date
When I shot the drummers, I was using the on-board mic and had the level turned down way low. At the instance where it poped, the audio levels did not peak. Surely this points to a fault with the camera? I've shot similar types of drummer performances many times with the DVX's on-board mic and Ive never had these kind of random pops.... I've had distortion with peaked levels - YES, but never clean audio with no level peaking and then randomly BAM, POP, POP...
BrianMurphy
Veteran
All I can say is I wouldn't use the on board microphones for anything other than an emergency on my DVX100B or my HMC150. Use the right mics for the work. Just because the level is turned down that does nothing about the mic diaphragm flapping like a sheet in the wind or at least I assume that is what is happening.
Brian: Totally agree, but under the same situation, the pop would not occur with the DVX. Unless you are saying that the deiminished on-board mic quality from the DVX to the HMC is acceptable...
I wasn't shooting for live-audio anyways... but still very disconcerting to hear the pop on such low leveled audio.. But what you're saying makes sense. Perhaps everything about the HMC is cost-cutting as opposed to the DVX which I feel was built to much higher quality standard..
Barry_Green
Moderator
Not yet. Keep meaning to.
I am also certain that it's going to be an SPL thing, but I don't know that I have the ability here to generate high-enough SPL's to cause the problem. I have a 150, a 170, and a 100 to use for a "control" camera.
SPL is a well-understood factor in mic selection, I mean, if you're recording explosions you don't use a condensor mic, you use a dynamic because the dynamic mic needs higher SPL levels. The high SPL of an explosion will damage a condensor.
So the question I have is: are we talking about a simple issue of the mic being too sensitive? Or is there something fundamental in the recording that people are running into? And the reason I question that is because some folks are saying that a direct XLR feed off the board is causing crackling too.
Now, if they're plugging in an external mic and getting crackling, that comes down to the mic again -- are they plugging in an external dynamic mic? Or an electret condensor? Or, worse, a condensor? Because if that's what they're doing, it's the same problem, wrong mic for the job.
But if anyone is piping a high-dynamic-range CD into their 150 and getting a crackling recording, then that's a way to isolate the mic away from the recording system and verify whether the recording system is solid.
Barry_Green
Moderator
Agreed 100%.
Now I just want to find an easily-repeatable circumstance that demonstrates the problem, where I can put a DVX100 into the same situation, to see if it performs the same under the same circumstances.
MattRobertson
Well-known member
hmm interesting.. You guys really think that its a mic problem? I don't get why it would distort coming off a board from a direct xlr feed if that was the case. Any ideas? I'm waiting to buy a hmc150 till I figure this out. I've never had this kind of issue on any camera i've ever used and it has me VERY concerned.
Barry_Green
Moderator
Well, that's the question that has me scratching my head. That's why I say we should try piping a loud-dynamic-range CD through the XLRs. If there's no clipping in the source, which there shouldn't be, and it's fed through line level and the receiving unit is set to not clip, then -- there should be no distortion in the recording either.
If there is, then there's something jacked up about the actual recording. That's why I was asking for repeatable circumstances to test this. I want to know for a fact that it's happening, so I can find out why.
MattRobertson
Well-known member
Yeah I agree totally, its quite puzzling...
Barry_Green
Moderator
Okay, I've just run about the only test that I can think of that should cause the problem (and cause it, it does). I put in "Live Free Or Die Hard", chapter-jumped to the shootout in Farrell's apartment, and I put the camera about 2" away from the subwoofer. I cranked the volume to the absolute max on both the subwoofer and on the receiver. I set the cameras so that they were recording about 12dB on average, and they never peaked into the red. The highest any of the cameras got was -3dB, so there's no danger of electronic clipping.
Did I get the snap-crackle-pop? I guess... It seems like it's there on both the 150 and the 170. But those who are romanticizing the DVX are wacky, because both the 150 and the 170 were 1,000,000,000 times better than the DVX100B at this.
HMC150 Audio File
HPX170 Audio File
DVX100B Audio File
Sorry, the 150 and 170 aren't a step backwards from the DVX, they're a huge step forward. I'm surprised they performed as well as they did.
You guys must be in some LOUD environments to be triggering this popping/crackling.
Did I get the snap-crackle-pop? I guess... It seems like it's there on both the 150 and the 170. But those who are romanticizing the DVX are wacky, because both the 150 and the 170 were 1,000,000,000 times better than the DVX100B at this.
HMC150 Audio File
HPX170 Audio File
DVX100B Audio File
Sorry, the 150 and 170 aren't a step backwards from the DVX, they're a huge step forward. I'm surprised they performed as well as they did.
You guys must be in some LOUD environments to be triggering this popping/crackling.
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D.R. Gates
Well-known member
Good test.
The link to the 170 isn't working (for me at least).
The link to the 170 isn't working (for me at least).
Barry_Green
Moderator
Fixed.
MattRobertson
Well-known member
Great Barry! This sorta gives me a sigh of relief and more confidence with the hmc150
Barry_Green
Moderator
Okay, for grins, I tried the DVX with the right mic for the job, a dynamic mic.
DVX100B sound file with dynamic mic
Sounds a little better than the on-camera mic did.
DVX100B sound file with dynamic mic
Sounds a little better than the on-camera mic did.
Green Hornet
Veteran
Just for the record,
When it happend to me, I was using one line in from a board, and the other mic from the camera, so it could have been only in one channel (the onboard mic channel). I was not controlling the board, so not sure how it was setup or the mics they were using.
I would not be so quick to say that the problem is the onboard mic simply getting too much SPL, as the camera in question was at the back of the room in this case.
It was far from the talent, and likely the spl should not have been so high as to cause this in this location, unless the base was boosted due to the fact that the camera was in a corner.
It could be possible that that same corner may have had the house speakers, in that location as well, I don't recall. If that be the case, it could be possible that that location (The corner of the room, with house drivers there as well), amplify the base, and therefore the SPL, to possibly cause this.
I thought i tested both channels to determine which had the pop (or both), but I can not remember. I will check again, but based on what Mr Green has tested, it would seem that would be enough, however, I feel a subwoofer at around 2" would be expected to cause distortion, regular listening music recording from 4 or more feet away, should not???
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Alright I'll contribute.. below is a screen cap from the vegas timeline with markers indicating points where the audio pop occurred.. As you can see, levels did not peak, wasn't even close, and sounds that registered just as loudly at other points in the footage did not pop.. I've also included a link to vimeo showing the video in question.. perhaps it has something to do with distance to the drum??? I guess my main question is, isn't it intuitive for the pops to correlate with audio level? If the audio levels never peaked, does it make sense not to expect distortion such as the pops here? Oh and the pop does exist on both channels.. This was recorded with the on-board mic.
Vimeo clip: http://www.vimeo.com/4385002
Vimeo clip: http://www.vimeo.com/4385002
Hi Barry, sorry to chip in on this HMC series, I would like to relate my problem on my DVX. In my place I shoot Chinese weddings, and then they have this door games (challenges) before they get their bride... and also the toasting (Yum seng) session. On both occasions they guys would scream out loud.. and I do face cracking problems with both RODE NTG-1 shotgun and also the on-board mic.
As you were saying that the HMC is producing a better result than the DVX in this criteria, but it does have some pop / crackles too ?? I do browse video forums quite often, but most of the complaints came from HMC, and my own on DVX with this pops ... never heard other brands complaining like SONY, canon ?? sorry if it's really my ignorance for never really searching through the forum. Posted my question a few times but never get any reply.
And if it's a problem of very high SPL, any suggested run around method for DVX in my case ?? Use a dynamic mic for only the games / toasting / high SPL situations instead of the shotgun ?
I'm really plunging into HMC 150 very soon, but currently in my editing I think I'm correcting the audio problems way too much .. I'm fed up . Don't hope my next camera, I would have to do the same ...
thanks ..
TheMusician
Well-known member
Boogerg2, I think that you are getting SPL and peaking confused.
A condenser microphone is just a thin membrane that vibrates and transfers an electical signal to an input, in this case, a camera. If the volume and sound pressure levels of a sound source are greater than the pressure that the mic can handle, it just starts flapping in the breeze and causes pops/cracks/distortion.
Now on your Vegas timeline, clearly it looks like the audio is nowhere near clipping, but that is a common misconception. Your camera has an input level that you turned down so that the CAMERA did not clip the audio. But every mic only has a certain pressure that it can handle before the MIC clips and that doesn't mean that wave has to be at 0db or above. I bet that if you look at the timeline carefully, you will occassionally see little flat tops on the peaks when you start to hear distortion, and that means that your mic is clipping, not the camera input.
Also, watch your clip on vimeo again. It clearly clips the worst when you get closest to the drummer. This is without question an SPL issue based on your clip. It's the mic, not the camera.
I know it is a little bit confusing, but your camera has an individual limit that you control with the audio dial, and the mic has its own limit where the only way to help is to back away from high sound pressure levels, or use a dynamic mic. Hope this helps, but I think this is a concern that barry's test clearly illustrates.
Also, I don't think that just because people are running a line off a board means that there should not be popping. If the sound guy used the wrong type of mics or placed them too close to the talent, then the signal off the board would have the same problems that we are seeing here. So test the mics.
By the way, the setting of your footage is beautiful!
A condenser microphone is just a thin membrane that vibrates and transfers an electical signal to an input, in this case, a camera. If the volume and sound pressure levels of a sound source are greater than the pressure that the mic can handle, it just starts flapping in the breeze and causes pops/cracks/distortion.
Now on your Vegas timeline, clearly it looks like the audio is nowhere near clipping, but that is a common misconception. Your camera has an input level that you turned down so that the CAMERA did not clip the audio. But every mic only has a certain pressure that it can handle before the MIC clips and that doesn't mean that wave has to be at 0db or above. I bet that if you look at the timeline carefully, you will occassionally see little flat tops on the peaks when you start to hear distortion, and that means that your mic is clipping, not the camera input.
Also, watch your clip on vimeo again. It clearly clips the worst when you get closest to the drummer. This is without question an SPL issue based on your clip. It's the mic, not the camera.
I know it is a little bit confusing, but your camera has an individual limit that you control with the audio dial, and the mic has its own limit where the only way to help is to back away from high sound pressure levels, or use a dynamic mic. Hope this helps, but I think this is a concern that barry's test clearly illustrates.
Also, I don't think that just because people are running a line off a board means that there should not be popping. If the sound guy used the wrong type of mics or placed them too close to the talent, then the signal off the board would have the same problems that we are seeing here. So test the mics.
By the way, the setting of your footage is beautiful!
D.R. Gates
Well-known member
His mic is a part of the camera. I don't think that's going to relieve his fears, as people have reported similar issues with external mics.