Topic: processing/fixing a recording with Audacity

[dimm0k]

So I recorded a show recently and during the opening band I realized the speakers really sucked so I had to push up the preamp all the way.  I also pushed up the recording volume on the MD player to give it an extra boost.  When the main attraction came on and I started recording I saw the meter on the MD player bounce a lot between the two markers indicating that it was close to clipping so I turned the knob on the preamp down.  I would have liked to turned the recording volume on the MD player down, but I can't adjust that whilst recording on this MD player.  Anyway so I go through the recording unprocessed through headphone out on the MD player into my car stereo and notice that in the beginning the volume fluctuates from adjusting the preamp and after the second song or so the volume is steady, BUT really low.  How should I go about fixing this recording?

[panther65]

I've had that happen many times. In Audacity I use the envelope tool. It's grouped with 5 other buttons to the right of the playback controls in the upper section of the window. Click on the upper-most part of the waveform window and it will place a marker. Put one more to the right of the first marker. Then at the point where the levels come back to normal, put another marker and then to the left of that another. You can play around with these markers until you get as even a response as possible.
If the levels are very extreme, very low and then much higher, I highlight that section and use amplify to get it as even as possible. Sometimes it's impossible to get everything just exactly level.

[dimm0k]

Should I do this before or after I normalize?

[panther65]

I don't normalize. Not sure what to tell you.

[Brian Skalinder]

Should I do this before or after I normalize?

Before.  In general, you want to normalize last, after making any edits.  Edits may change levels, which could either impact the normalization process itself, or reduce your levels post-normalization.  Since the goal of normalization is to set your final peak levels, you should edit first, then normalize.

[Roving Sign]

And in Audacity:

Effects > Amplify = Normalize

I think the Audacity "normalize" actually does some thing else...

[Brian Skalinder]

And in Audacity:

Effects > Amplify = Normalize

I think the Audacity "normalize" actually does some thing else...

Good tip.  I think Audacity's Normalize function (Effects > Normalize) still performs peak normalization, which is what most people want (as opposed to RMS normalization), but the max peak in the Normalize function is fixed at -3 dBFS (can't change it).  Effects > Amplify, as RS notes above, also basically performs peak normalization, but allows one to set peaks to any level.  The Amplify feature automatically determines how much gain to add to reach peaks of 0 dBFS.  If you want to set peaks slightly lower than 0 dBFS, then simply adjust the New Peak Amplitude field accordingly.

[dimm0k]

Hrmm, I'm a little overwhelmed on what to do with the recording after importing it into Audacity.  I'd like to raise the music and the banter in between to better levels so my "plan" is as follows:
there's one specific range in the recording, applause mainly, that maxes out at 5 for Amplify so I've amplified the sections before and after this range to their max, 6.4 and then Amplify that specific range to 5.  From there I go to each section of music and banter and Amplify 1.5 and 2.5 respectively.  Am I going about this correctly?

What would the difference be if I were to envelope the applause first and then Amplify the whole thing across, followed by a boost to just the banter?

[Brian Skalinder]

What would the difference be if I were to envelope the applause first and then Amplify the whole thing across, followed by a boost to just the banter?

I'd go about it roughly as you indicate above, but with a slight change in the order:

• use the amplitude envelope to reduce the applause peaks to a more tolerable level
• use the amplitude envelope to also boost the banter
• amplify / normalize the whole waveform
• export to the final destination format (e.g. 16-bit/44.1kHz)

I also recommend ensuring you have Audacity configured properly for your editing and output formats, per this workflow thread.

[dimm0k]

Thanks a lot Brian.  One thing that came to mind was, what's the difference between amplifying and using the envelope feature to boost certain sections?

EDIT:  finally got home and am now messing around with the amplitude envelope to even out the sections that I can hear a difference in sound levels from the adjusting of the preamp.  After closely matching a lower section with the beginning where it's louder I noticed that when I play it through Audacity that the meter shows red, meaning it's clipping.  If I highlight those sections and attempt to run Amplify on it it allows me to adjust up to 5 and the volume definitely increases, but the meter hits those red levels even more.  What does this mean?  I thought Amplify wouldn't let the section it's amplifying clip unless you tick the box that says to allow it.  Did I miss something?

[Roving Sign]

Thanks a lot Brian.  One thing that came to mind was, what's the difference between amplifying and using the envelope feature to boost certain sections?

EDIT:  finally got home and am now messing around with the amplitude envelope to even out the sections that I can hear a difference in sound levels from the adjusting of the preamp.  After closely matching a lower section with the beginning where it's louder I noticed that when I play it through Audacity that the meter shows red, meaning it's clipping.  If I highlight those sections and attempt to run Amplify on it it allows me to adjust up to 5 and the volume definitely increases, but the meter hits those red levels even more.  What does this mean?  I thought Amplify wouldn't let the section it's amplifying clip unless you tick the box that says to allow it.  Did I miss something?

Not really - just dont raise the levels so high that you force clipping...the Amplify effect wont do it unless you uncheck the box...but perhaps the envelope tool allows clipping...

The difference is the envelope will allow you to basically "fade in/out" any amplitude changes so they are not so abrupt...very handy for compensating for mid-song level fluctuations as you describe...