Cleaning up audio file

[test-card girl]

I'm editing together a few clips for a demonstration video. The sound quality is very poor, with a constant "hum" in the background. Is there any way to clean this up without getting rid of the voice or am I asking the impossible?

A decent mic is a must for future projects, it'd just be a shame if recording this has been a complete waste of time.

I'm completely new to this package and indeed, video editing generally. Just making it up as I go along...

Would appreciate any suggestions.

Cheers!

ETA: I'm using the VideoStudio 10, Standard Edition (which actually came free with a firewire card and seems a lot better than Windows Movie Maker, which I was originally using!)

[Black Lab]

VideoStudio is a pretty decent video editor, but it is lacking when it comes to audio editing. Many on this forum use dedicated audio editors. A good free one is Audacity. But I must caution you. Since the hum is throughout the video it will be nearly impossible to isolate, so don't expect miracles.

[test-card girl]

Thanks for the reply, Jeff. Doesn't sound too hopeful then. I'll take a look at Audacity but I fear it might be beyond me at this stage!

[Black Lab]

By the way, your VideoStudio SE, does not stand for Standard Edition (IMHO), but more accurately should stand for Stripped Edition or even Sub-Standard Edition. In reality it is most probably a cut-down version in some regard (that's why it was free ). Some can't burn, others are missing the ability to handle Dolby, etc.

If you find you like VS I would suggest looking into upgrading to a full edition. I will advise you though, that it is anticipated that version 12 will be released in the near future.

[test-card girl]

Ah, cheers, Jeff. Although this was free (and so not to be sniffed at!) the regular version looks like pretty good value so I will probably upgrade - especially if it can be downloaded.

I've been looking at external microphones but it looks like a minefield! Got to be better than this tele mic from Jessops though...

[DVDDoug]

Note - I don't use Audacity. (I use a non-free audio editor.)

Here is a link about Audacity's Noise Reduction Filter (And from there, you can find the Audacity download page too.)

In general noise reduction works well when there is a constant low-level background noise. If the hum level is low enough, compared to your desired sound, you can probably remove it. The software will have trouble if the noise-level jumps around a lot, or if the noise is as-loud as the sound you are trying to record. Sometimes you have to compromise between leaving some noise or removing some of your desired-sound. (Noise reduction works best when you don't really need it.)

A decent mic is a must for future projects...

It's not just the quality of the mic... It's important to get the microphone close to the source and it's important to minimize the ambient-acoustical background noise.

In general, you can't duplicate what the pros do, but you can learn from what they do... Mostly, the pros try to prevent noise. Professional recordings are made in soundproof studios with good (low noise) preamps & mixers. TV reporters (in soundproof studios) use lapel mic's within about a foot of their mouth. When they do "on-location" reporting, they speak directly into the microphone, and if they are outdoors they use a mic with a wind sock... Still you can often hear background noise when the reporter is on location.

Most movie dialog is re-recorded in the studio.

- An excellent recording doesn't need any processing.

- Digital processing can turn a good recording into an excellent recording.

- If you have a bad recording, the cure can be worse than the disease.

[test-card girl]

Thanks for the reply, Doug - that's really helpful. I will have a bash at the noise reduction filter.

I'm mostly going to be recording interviews, where two people are seated at a table, to be used for training / demonstration purposes. Do you think I'd be better of with a microphone that could be placed on the table, rather than fixed to the camera? The camera is by necessity a few feet away. The range out there is pretty overwhelming and from looking at a digital editing forum people seem to recommend equipment that is far too expensive for my budget. We could probably stretch to a couple of hundred pounds if it will significantly improve the sound quality.

[Ron P.]

Lapel mics are the better type. They are placed within 12 inches (most are within 8 inches) of the speakers mouth, pointing up towards their mouths of course.

Since you're going to have more than 1 speaker, you would need to have either an audio mixer, or separate audio recorder that can handle more than one audio input channel. You would also have to ensure that a "sync" point exists when you start recording, so that the audio and video can be synced up in post production.

It may suit your situation to purchase an external mic. Some of these are not that expensive. I know budgets are of great concern, but if you're producing videos for profit, then I would think that you would want to try to achieve the best possible quality. Built in camera mics are generally very low quality, and even have a tendency to pick up camera motor noise.

Some of the more expensive camcorders have what's called a "low-z" mic input. These are for low impedance microphones, the type the "pros" use. The jacks are larger, then the more common ones found on consumer models. The small jacks or mini-plugs are high-impedance, and they tend to pick up the hum.

One issue with using a single mic for multiple subjects is being able to pick up each person at about the same volume level. Even placing the mic between them can cause one persons voice to be more predominant, which can be from the mic itself or from the pitch of the persons voice, and everyone speaks at different volume levels.

The humming noise could be from the lighting used. Fluorescent lights seem to generate this type of hum. Try using a different type of light, such as spot/flood lights.

The way the building is wired (or miss-wired) can also produce this. This would be to an improperly grounded system. I know in my house there are some rooms that seem to produce this "60 cycle hum", which is from the electrical outlets. Other rooms do not.

One possible source here in the US that I used to pick up some more expensive audio equipment, was what's called pawn shops. These are stores that people could "pawn" items for cash. If they did not repay the loan (pawn), the item was then kept and resold by the owner. Most of the time the loan on the item was small, so when resold the store owner was mainly concerned about getting the loaned amount. I've purchased $200-400 (US) mics for only $50, amplifiers for next to nothing. (This was back in my bar-band days, where we were assembling our audio systems). So I don't know if such outlets exist overseas, but it if so check into them, as some good bargins are found there.

[test-card girl]

Thanks, Ron. We do have pawn shops and similar in the UK so I'll bear them in mind. I'd thought about using a lapel mic but wasn't sure how I'd go about having two microphones. I'll look into audio mixers.

The videos aren't for profit but I do still want the quality to be as good as possible -- within the confines of my sadly limited expertise in this area (although I guess there's only one way to learn) and of course the limited budget of a public sector project!

It's interesting. I thought that transferring the tapes to computer and adding titles etc would be the tricky part. I'm beginning to see that the sound quality is as important as the visual, if not more.

[Black Lab]

I'm beginning to see that the sound quality is as important as the visual, if not more.

I rented a movie once (sorry, forget the name) and among its extras was a "making of" and it showed the effects of music and sound to a film by removing the sound effects one by one until only the actors voices remained. WOW! What a difference sound (and good sound at that) makes.