Moving The Waveform To 0

[jahoh]

Hey Guys,

I have this really quiet audio file I'm trying to edit, and it never passes by the zero crossing, so I can't export it without annoying clicks.

Is there anyway I can move the whole wave so it passes through 0? The only option I could think of was inverting, but that didn't work.

Thanks a lot.

[Trebor]

Audacity's "Normalize" effect has a "Remove DC offset" option which may be of help.
If you don't want to change the volume don't tick the "Normalize maximum volume to ..", just tick "Remove DC offset".

[whomper]

Audacity's "Normalize" effect has a "Remove DC offset" option which may be of help.
If you don't want to change the volume don't tick the "Normalize maximum volume to ..", just tick "Remove DC offset".

dc offset can cause ticks ??

i thought that was when there was a jump in the signal
like when you made a bad splice instead of splicing at a zero crossing

a low volume can have noise including ticks and pops
mewonders if he meant normalize up to zero db for better signal?

[jahoh]

Audacity's "Normalize" effect has a "Remove DC offset" option which may be of help.
If you don't want to change the volume don't tick the "Normalize maximum volume to ..", just tick "Remove DC offset".

Thanks a lot. That did just the trick.

You've saved me a lot of tooth shavings!

[kozikowski]

<<<dc offset can cause ticks ??>>>

It's the leading cause.

<<<like when you made a bad splice instead of splicing at a zero crossing>>>

You can get a little one there, but it tends to get hidden by the surrounding show. DC offset can give you a clear pop when there's no show sound at all like when you're trying to edit dialog word by word. It really stands out.

A common problem is to get half-way through editing and try to fix it then. Too late. You need to remove DC before you start editing.

Koz

[kozikowski]

<<<mewonders if he meant normalize up to zero db for better signal?>>>

Very unlikely. Most people edit in the percent scale...

http://kozco.com/tech/audacity/Audacity1_playback.jpg

...so they wouldn't know where zero dBFS was.

Koz

[Trebor]

dc offset can cause ticks ??

BEFORE-AFTER DC OFFSET REMOVED.PNG (45.15 KiB) Viewed 1604 times

When the "before" track ends there is a loud click at the very end as the output returns to zero, (ringed in red).

"after" the DC offset is removed the track is zero when it ends, so no click.

[whomper]

<<<dc offset can cause ticks ??>>>

It's the leading cause.

<<<like when you made a bad splice instead of splicing at a zero crossing>>>

You can get a little one there, but it tends to get hidden by the surrounding show. DC offset can give you a clear pop when there's no show sound at all like when you're trying to edit dialog word by word. It really stands out.

A common problem is to get half-way through editing and try to fix it then. Too late. You need to remove DC before you start editing.

Koz

i can see it if you edit
because then there is no zero crossing point

but if you just play back ?? does dc offset cause noise/clicks then ??

[steve]

This is drifting way off topic as the question from jahoh was answered accurately and succinctly in the very first reply (thanks Trebor).

DC offset is likely to produce a click when the track starts playing and when it stops playing. It can cause additional clicks if it is edited with audio that does not have DC off-set or has a different amount of DC offset. DC offset also reduces the amount of available headroom. In extreme cases it may cause unnecessary stress on amplifiers the playback equipment and can lead to premature failure of the equipment. DC offset is a 0Hz signal and should not be present in audio recordings. For more information see http://www.google.com/search?q=dc+offset