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Psychomaniac
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Discussion Starter #1
I've been messing with this for a while in Audacity but I'm just not up to speed on the correct way to do this.

I have prop that's motion activated. The sound effect comes off a MP3 player. Since I lack a way to hit "play", I need a constant sound. The motion sensor will turn on amplified speakers when the time is right.

Here is the sound effect...

roar.wav

I tried taking off the beginning and ending and then repeating the rest but there is a glitch when the clips meet. I messed around with the waveforms and tried to get them to line up without success.

There are already two glitches in the file and I was working with the audio in between (one at around .4 seconds and another at around 3.4 seconds.

I need this looped to about ten minutes and then I'll repeat it on the MP3 player.

Can anyone help or give me some tips on how to do this right?

Thanks!
 

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Psychomaniac
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623 Posts
Discussion Starter #5
Thanks for the help you guys! I know Audacity pretty well but all my sound mixing experience is self-taught and hobby level so I decided to quit banging my head against the wall on this particular one.

The original file is linked in the first post. I'll PM my e-mail address to you.

Thanks again!
 

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Is it your everyday MP3 player so you don't want to modify it? If not, adding a play command from the motion triggered prop should be relatively easy.

If it is your everyday player, is a reasonably priced remote available? You could modify that instead.

For looping the clip, the best way I can think of is to pick a clip with similar amplitude at the start and stop points. Then apply a fade in and fade out. Overlap the fade out with the fade in to disguise the transition.
 

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I can fix your problem, but instead, I recommend a different sound. the file you have is overmodulated and distorted so badly that it's hard to tell what it is. To me, it sounds more like a train horn than a growl. I have some good growling sounds. I can make a loop of one for you if you like.

I will try to explain how it's done in a couple hours when I have more time.
 

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Psychomaniac
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623 Posts
Discussion Starter #9
Morning all! Yes, it is the T-Rex from Jurrasic Park. It's the best clip I've found so far but I know it's over-modulated and clipped. My daughter complained that it sounded like an elephant! I can try and pull a new sample off the DVD and see if I can improve the quality. I'll give that a shot tonight. I'd be very interested in hearing the roars that you have.

DeathDealer, I do have a handful of Sansa C140 MP3 players dedicated for Halloween. I was going to modify it to be activated by the relay in the prop controller I built but I'm running out of time. I can also be a little more flexible with my timing this way because the play button is also the pause button on the Sansa. Since I'll be switching the speakers on at this point instead of starting the sound I'll need the clip to be constant. No fade in or out.

I'll take a closer look at the Sansa tonight and see how much it'll take to get in there and access the pads for the play switch.

Thanks again for all the help and feedback!
 

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Try this clip:

http://rewindshow.com/skull/ShortGrowlingLoop.wav

You won't find that anywhere else. It's actually me on my microphone, but I pitched it down a bit.

If that isn't the kind of sound you were looking for, I have others, but if you want a continuous loop playing, you probably don't want a sustained Roar that never ends.
 

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Psychomaniac
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Discussion Starter #11
Ha! That's pretty good. I actually do want a sustained roar that never ends. The sound will play continuously and the prop controller will turn on the amplified speakers when triggered by the motion sensor. This also activates a tree shaker and lights. Since the speakers can come on at any point in the sound clip it needs to always be at full song.
 

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Not trying to be pessimistic, I know how we all get with 11 days out. But for a 'roar', if you activate the speakers hard on/off - won't that sound kinda weird? You want the roar to fade away, not just abruptly end like someone just tripped over the cord and pulled it out.

I too am looking for a quick fix to a issue I found with my set of MP3 players...and played briefly with just controlling the speakers instead, I didn't like it at all. Unless you can control the volume, you should experiment with it before comitting to the idea.
 

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Psychomaniac
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623 Posts
Discussion Starter #13
I'm going to see about cracking open one of the Sansa units tomorrow but I did some more tests and I'm happy with the current solution.

I recorded the sound clip myself at 44KHz tonight. Here's the full clip uncompressed...

Complete roar

The two "glitches" I mentioned in the first post are other sound effects in the scene. When the clip is looped they become repetitive and very noticeable.

Here's a clip with just the middle of the roar...

Roar clip

That second clip, looped with no glitches would do the trick nicely.

Thanks!
 

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I was suggesting the fade in/out not to be heard but to overlap so there is no hard transition between the end of one clip and the beginning of the next. It is a cross fade, but both tracks are the same, so the transition should be masked.
 
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