Audacity Forum

I think I found my answer a few days ago, but after a couple of hours of searching I can't find it, so reluctantly I'm posting this request.

I have a series of cassette tapes that contain my grandfather's oral history. They were made over a period of weeks and the volume levels vary from session to session. I have imported and edited them. I combined them into a single track, with each "snippet" labeled. (Isn't Audacity's ambiguous use of "tracks" confusing !).

I have tried, using amplify, to level out the volume of each snippet. However, there are 83 snippets and it is difficult to make them all the same level.

After the use of amplify I selected the entire track (all 83 snippets) and normalized it. It appears that volume of the entire tape was reduced, but that snippet-to-snippet levels remained about the same.

Any suggestions on what further to do?

TIA

Both Amplify and Normalize change the whole show once such that the highest peak anywhere in the show is at a set level. Amplify does the same thing to both left and right and Normalize changes each side independently.

You could try Chris's Compressor...

Chris's Compressor
http://pdf23ds.net/software/dynamic-compressor/

That one changes each phrase, note, and word to even out the whole show beginning to end. However, since you have cassette tapes, the background hiss level is going to migrate up and down along with the performance.

Give it a shot.

Koz

Koz,
Thanks a lot. I have already removed the cassette hiss with noise reduction, as well as the various clicks and pops from bumping the microphone, etc.

I'll give Chris's compressor a shot.

FWIW - it appears that several people have had exactly the same problem I have. Maybe Chris has the answer?

BTW - I found your excellent discussion on the purpose/theory of dynamic compression. Very nice. I think I even understand it!

Audacity has its own compression and limiting effects tools as do many other people.

You can mess with them forever and try different settings and post suggestions and read other people's experiences and sacrifice small furry animals at great length, or you can just apply Chris. Chris's talent is to make the show sound good, clear, and professional with a one-stop tool. That was his design goal.

I change one setting of the whole pile (the top one, compression) from 0.5 to 0.77 and the processed show is indistinguishable from the local NPR radio station.

Given I'm starting with relatively clean masters, no cassette tape hiss or other distortions. The only thing wrong is level variations.

I think I posted on his web site that "you have no idea what you have here..."

Koz

Koz,
I tried the compressor, but no success. It appears there is a memory management issue. I got an application error.

I have Audacity 1.2.6 for Windows and compressor 1.2.3.

The file is about 6 hours long.

Should I:
1. Apply the compressor to only parts of the file?
2. Switch to Audacity 1.3?
3. Modify the compress.ny (as show in Chris's metablog)?
4. Switch to Audacity 1.3 and the newest nyquist?
5. Some combination of the above?
6. Something else?

TIA

FWIW - I tried the standalone version of Chris's Compressor on the entire WAV file and got an application error.

I posted the details to Chris' blog.

(Also, I checked the link for a version of Audacity and an improved nyqist. The link no longer works. It was a bit dated, so perhaps the latest Audacity already has this included)

Oh, I think it's a lot worse than you think it is. Audacity does everything internally uncompressed. With the UNDO storage I figure your 6 hour show needs about 10 GB of blank hard drive plus the 10% free that you need to keep the computer from going insane. Let's say an 80GB system drive that would be 8GB plus the show would be 18GB clean, free space just to manage the show. That's bare minimum.

How much do you really have free? I'm guessing not enough. Audio (and video) production always catches everybody off guard.

Koz

Koz,
The free space was an issue, thanks for that tip, but not the entire problem.

I tried to compress my 6 hour WAV file on a drive with 40GB free space, using Audacity 1.2.6. The good news is that it continued to run. The bad news is that it never completed. I let it run for about 18 hours before I killed it.

The compression progress bar was a little over halfway when it really started slowing down. It initially said something like 20 minutes remaining, then as the hours went by the progress bar didn't move (if it did it didn't move much) and the estimated finish time started climbing. When I went to bed it had 10 hours remaining, this morning it had 21 hours remaining.

(Aside - what is interesting is that after I killed it I got a message asking if I wanted to install a .NET assistant, though it recommended against it. This implies that the Audacity plugin uses .NET, but that was only listed as a requirement for the standalong compressor)

Seriously large shows are Very, Very, Very Messy. When was the last time you defragmented your hard drive? Audacity will not work into a badly fragmented hard drive. Error check while you're in there.

You are probably going to run into the Windows 2GB and 4GB size restrictions and that WAV files will not go over some number...I think 4GB. 700MB per hour, 6 hours, 4.2GB.....

Break up the show into smaller chunks. That should make you a lot happier.

Koz

Koz,
I think those are red herrings. The disk was freshly defragged before attempting to compress the file. I'm using the NTFS file system which doesn't have those limits.

FWIW - the WAV file is 3.61GB

I think the bottom line is that, as of right now, Chris's compressor plugin won't work on files as large as mine.

The standalone compressor failed in the output phase after the peak analysis was done. So perhaps it will work once the bug is fixed?

In any event I manually amp'ed the show segments to get what I wanted. At least it is good enough for now.

Thanks!