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Video sound, microphones and editing

Discussion in 'Photography' started by RalphW, Oct 3, 2009.

  1. RalphW

    RalphW Nat Pres stalwart Staff Member Administrator Friend

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    Does anyone know if there is any software that can be used to remove unwanted background noise. Ideally by recording the background before the train arrives, like the hum or roar from nearby traffic, and then using it to remove that element from the sound track?
     
  2. BillR

    BillR Well-Known Member

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    Sounds like you are thinking of Phase inversion.
    trouble is any pre-recorded background noise is never going to be a spot on replica of the background sound when you want to record the subject. Hence phase inversion will not work.

    Now if you had a device that took input from your main mic & input from a secondary mic, it may be possible to phase invert and remove background sounds in the same manor as noise canceling headphones.

    Hums and other constant sounds may be removed with filters.
    Try Audacity, it's free http://audacity.sourceforge.net/about/features
     
  3. RalphW

    RalphW Nat Pres stalwart Staff Member Administrator Friend

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  4. Orion

    Orion Well-Known Member

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    Wind noise

    My big bugbear is wind noise. I get the impression from the blurb on the suggested software that it won't deal with this.

    I have put various shielding devices over the mic with some success in reducing the problem, but it didn't work last weekend at Minehead, the wind was just too strong. The camera and the Corel and Pinnacle editing suites are supposed to have features to solve the problem but don't - they're useless.

    Does anybody know of a software filter that will do the business?

    Regards
     
  5. BillR

    BillR Well-Known Member

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    There is none. Wind noise is too erratic. Shielding the mic is the only way that's why TV news reporters always have a big furry thing on their mic's.

    Eliminate at source.
    If your cam has an external mic socket, use an external mic, they are far easier to shield. If you are thinking of buying a new cam, make sure it has an external mic connection and it's a standard 3.5mm jack not a 'hot shoe' or other connection ( of course XLR is OK, but that costs a fair bit more).
     
    Corbs likes this.
  6. royce6229

    royce6229 Active Member

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    Hiya Bill. Quite agree with you about wind noice, the only way to deal with it is stop it at source. Heres a shot of my Zeppelin at Blea Moor, works a treat but not very practical without a seperate sound man.
     

    Attached Files:

  7. RalphW

    RalphW Nat Pres stalwart Staff Member Administrator Friend

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    Thanks for the input on this, as I said in my original post, it's not wind noise that I am concerned with as foam and furry covers deal with all but the worst of that, it was other things like traffic noise, but it seems there is little that can be done about that.
     
  8. noelist

    noelist Active Member

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    you can edit sound tracks with software used buy musicians in recording studio's, the sound track is displayed across the screen, see here:-

    http://audacity.sourceforge.net/

    click on the screenshot to see a selection of what you see on your PC screen.

    you can move your cursor along the displayed sound waves and they play through your speakers as you do.
    you can pinpoint the sound you want to remove.
    removing one of two sounds is more difficult,
    replacing the blank space with a more desirable sound is easy though.

    surely there are musicians on here that know of more sophisticated software.

    hope this is of interest.
     
  9. Orion

    Orion Well-Known Member

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    I do use an external mic, a Rode SVM, and it's equipped with a 'furry cat' windgag. So far so good. It works well in most wind conditions but when it's really blowing as it generally does on the WSR in the spring or autumn it's not so good. I used to use an ATR25 equipped with a Rycote softie and a Rycote flexible mount but it wasn't as good as the Rode and in a wind the Rycote mount would bend this way and that vibrating the camera on the tripod. Then I would take the mic and mount off the camera but it all became a bit of a handful if I wanted to pan and zoom.

    Probably the best idea is to use a totally separate mic with a very elaborate system of shielding but as 'Royce6229' said you need a sound man.

    In principle it should be possible to design a software filter which does the business. You don't really want to suppress all the frequencies of 'wind noise' what you want to do is to suppress the distortion that comes with the noise being too loud and that will always be at a small range of frequencies and their harmonics. It should be possible to do this, the Rode has a hardware filter which does the job OK in moderate conditions but it's not good enough when it's really blowing.

    Thanks for the input, I'll carry on looking.

    Regards
     
  10. Spamcan81

    Spamcan81 Nat Pres stalwart

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    "Dead cat" wind jammers are ok to a degree but they work better
    if used in conjunction with a wind cage. I was using just such a combination
    up on Rannoch Moor the other day. The conditions were challenging shall we
    say. By far the windiest I've ever tried to record in and I was
    pleasantly surprised with the results.
    As for traffic noise, a directionali mic can help but not if the traffic
    is in front of you.
     
  11. BillR

    BillR Well-Known Member

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    But that's the problem, when wind is enough to be a nuisance it totally distorts the sound track, no amount of any filter can replace what has been totally covered with distortion (clipping).

    I did a topic on here before the forum change about making a DIY blimp (seems to have been lost), I reckon it's good for 60mph+ winds. If you still have the ATR25 it may be a good experiment. My blimp is fixed to a home made bracket on the tripod so panning is no problem. Have a look at my Cambrian coast video in my signature below, the clip that starts at 2:50. The wind then was atrocious, I could hardly stand and when I panned around, the camera having the full force of the wind on it's side, actually lifted off the ground! Yes you can hear wind noise, but it is the sound of the wind through the grass rather than the deep distortion rumble.
     
  12. Orion

    Orion Well-Known Member

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    Well I 've had a look and I'm seriously impressed both by the sound and pictures! 5*****; brilliant.

    The ATR25 doesn't work too well with my current camera which is a Canon HG10. The sound is muffled, hence the change to the Rode SVM which was recommended to me. Could you repeat the topic you did about making a DIY blimp? I'd be most interested, anything that will either create a layer of still air around the mic without affecting the quality of sound too much

    MTIA

    Regards
     
  13. BillR

    BillR Well-Known Member

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  14. blackfive

    blackfive Active Member

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    Blimp covers, far cheaper than Rycote, can be had from Indikit.
    They also do Rycote style baskets which aren't quite so cheap.
     
  15. Steamage

    Steamage Part of the furniture

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    Bill and Royce are right about wind-noise. Once your sound is distorted, no amount of post-production software can restore it. I use a Rycote Softie and a Rycote Windspoiler on my Rode NTG-1 mic, mounted in a Rode shock-mount and covered with a home-made fur cover. This set-up is small enough to fix on the camera shoe-mount. It's not quite as thorough as a proper basket, but it was fine on the West Highlander in September, and the only time this year my sound has been completely unusable was at Abington for the Great Britain 2 in April, when the wind was so strong that my tripod almost blew over. Those who've seen me out and about will know that I use a very sturdy Manfroto tripod, and it takes a lot to topple it!

    If you are using a stereo mic, such as the Rode SVM, you might do better putting it on a separate tripod than having it moving with the camera. This gives a more convincing sound stage. Then you can use a blimp and not worry about it upsetting your camera (but you must carry it around and set it up at your location!). You might have problems with the cable picking up unwanted noises, especially near overhead power lines, but if you keep the cable quite short (and don't use it coiled up) you'll be OK most of the time. (Mics that use stereo mini plus are - normally - unbalanced and so can pick up noise from the cables. Mics that use XLR plugs are - normally - balanced, so that noise picked up by the cable can be cancelled out at the other end.)

    Reducing background noises can be done, depending on what the sound is like. Narrow frequency noise, like mains hum or air conditioning can be removed quite effectively with Noise Reduction (NR) filters. Find a sample of just the background sound that you wish to remove, then feed that and the real sound track into a program such as Adobe Audition. Start by reducing it just a small amount and mess about with the settings until you like what you hear. You often get better results by re-applying gentle reduction with slightly different frequency settings several times than trying to remove everything at one hit. In fact, don't expect to remove everything. Just reducing the annoying background a little will let you hear the subject more clearly. If you over-do it, the result will sound hollow or thin because you will have removed the noise frequencies from the subject as well as the background. It really helps to have a good pair of speakers for this, not the usual cheap plastic things that come bundled with most computers. When you are listening for subtle changes, you need to be sure your speakers are telling you the truth.

    I have used Audition when cleaning up old S-VHS video that had too much camera motor noise. I recorded a special sample of just the camera noise by plugging my old camcorder mic into a minidisc, mounting it on the camera, and recording it under a duvet, to be sure there was nothing except the camcorder noise on the recording. I found three particular frequency bands where the motor noise was intrusive and did a couple of passes gently reducing each problem area. I then mixed between the NR version and the original, so that sections that were not badly affected were left alone, sections with a bit of a problem got a modest amount of NR and only the really bad bits got the full treatment - even then the final track was probably only about 65% the NR track.
     
  16. RalphW

    RalphW Nat Pres stalwart Staff Member Administrator Friend

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    Someone was asking about mics etc for video cameras so I've found this thread and brought it back into view....It contains Freds advice on building a 'blimp'.
     
    Last edited: Apr 23, 2014
  17. Steamage

    Steamage Part of the furniture

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    Thanks Ralph. Sadly, Bill's PDF is no longer at that location.
     
  18. RalphW

    RalphW Nat Pres stalwart Staff Member Administrator Friend

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    Oops never checked, I hope Bill still has it somewhere I'll PM him and ask.
     
  19. BillR

    BillR Well-Known Member

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    Just had a search on my PC, sorry to say that pdf has long gone.
     

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