I've been using iMovie on my MacBook for some time now, and usually the built-in mic works fine, whether the singer/instrumentalist is amplified or not. It's just a matter of setting the input levels right (e.g., lowering the input levels if the amplified sound is too loud, so you don't get distortion).

But some strange and frustrating things have happened from time to time.   Once, about 2 years ago, I 'recorded' a whole hour-long program and got the video part just fine but no sound whatsoever.   I hadn't changed the mic input levels.
Then a few months ago I tried to record a choir concert at our church, and I had the laptop (the built-in camera and mic) in the balcony, about 30 feet from the choir and pulpit area. The speakers in the church are placed at various places, so the sound seemed to be loud enough that it should have worked well. But I got, again, good video but no sound except a lot of very loud, intermittent static.

Recently I tried to record myself singing, sitting with the laptop on (guess where) my lap.   This time my voice did record, but there were bursts of static throughout. So I moved the laptop to a table about a foot further away (and where the laptop would remain totally starionary) and tried again. Same result.

Just a few days ago I recorded a mini-concert/sing-along that I did with no amp, just singing and my acoustic guitar.   The laptop was on a stand about 6'-7' from me.   This time the vocals and guitar came through a little bit on the soft (low volume) side but otherwise very natural sounding -- only most of the time during that hour-long program there was an overlay of static. On a few songs it was hardly noticeable and on a couple it was very distracting. For the most part it sounded like playing an old, scratchy 78 rpm record.

Thing is, at other times throughout this 2 1/2-year period I've recorded hours and hours of music under the same conditions -- with and without amplification, having the laptop (mic) a foot or so from the input source or 10 feet away or 20 feet away, etc. It's not as though the program and computer used to work but have gotten worse. It's very sporadic and seemingly unpredictable.

I'm wondering if anyone else has experience with and knowledge about Mac's built-in mic and iMovie. Does this sound like something's wrong with the built-in mic (e.g., does it need to be cleaned)?   Does it sound like a software glitch?   Are there any handy, inexpensive remedies?   Would it help to re-install iMovie?



One other thing. Is there a way to tweak the sound on audio-video files e.g., mpeg or .mov or quicktime files (e.g., the way they "digitally remaster" old records) after you've made the videos? Can Garage Band do that?

Any help will be appreciated.