Recs on how to compress

[edmund10]

Hi Everyone -
I thought I would create a new thread for this since I am starting again.

I need to convert a bunch of lectures in .ogg format to mp3.

I used cleanspeach last time and I was still getting clipping.

This is the original waveform ---

What are your recs for how to compress this file into a small mp3 without surges in volume. I image there is something far more simple than what I was doing.

They are just lectures, so dont care about dynamic range. Just want it easy on the ears!

Thank you all!

[steve]

Could you upload a short(ish) audio sample somewhere on the Internet and post a link so that we can hear it.

[edmund10]

Thanks for taking the time to listen to this:


http://www.mediafire.com/?pzc7oyhlk9mlyy7

And this is the exported .ogg

http://www.mediafire.com/?5vot6bbyosd00nw

Ultimately I need it to be a relatively small mp3, but just kept in ogg after trimming as that was the original.

Thank you!

[edmund10]

Thank so much --- very informative!

I had used the latest version of Cleanspeech.

However, that .ogg I uploaded is the original. And I am looking for recs on how to get rid of any clipping and I suppose minimize the dynamic range. Essentially, I just want to listen to the lectures without the surges of volume. I was thinking that Cleanspeech may not even be needed and a few other simple effects could be used.

Thoughts?

Thank you again!

[steve]

[Update: I see that you have replied while I was updating this post, so apologies for any confusion.]



The first file is a .AUP file. This is an Audacity Project file, but it is only part of the project. It contains no audio data, so I can't play it.
See here for a description of Audacity Projects (this is quite important information) http://manual.audacityteam.org/man/Audacity_Projects

From looking at the exported .OGG file, I think that I can see what the problem is and why you are getting those clipping lines.
I think that it's due to a problem with your CleanSpeech settings.

If you are using the CleanSpeech Chain, here's some step by step instructions that I think should fix the problem:

1. File menu > Edit Chains
2. Click on "CleanSpeech" in the left hand panel
3. In the right hand panel you will see that Normalize is listed twice. If the "Level" parameter is set to a positive number, they will need to be changed.
4. Click on Step 02, Normalize
5. Press the spacebar to open it for editing
6. Click on the "Edit Parameters" button
7. Set the number in the text box to "-1.0" (without quotes)
8. Click the "OK" button
9. Click the next "OK" button
10. Click on Step 07, Normalize
11. Press the spacebar to open it for editing
12. Click on the "Edit Parameters" button
13. Set the number in the text box to "-1.0" (without quotes)
14. Click the "OK" button
15. Click the next "OK" button
16. Click the next "OK" button

[steve]

I had used the latest version of Cleanspeech.

If you ever used Chains in an older version of Audacity, then the old Cleanspeech settings will most likely still be on your computer.
The (revised) notes in my last post should set them to the correct settings for the new version of CleanSpeech.

However, that .ogg I uploaded is the original.

The original what?
You previously said "And this is the exported .ogg"
Wherever that .ogg file was exported from, the level was too high and it has clipped (distorted) the waveform.

[edmund10]

Thank you --- I just tried it out.

However, let me rephrase my question.

Without using Cleanspeech -- what changes do you recommend I use on the ogg I uploaded to make it sound better. Seems to me there is a lot clipping because of a wide dynamic range. Thank you.

[steve]

Clipping is notoriously difficult to repair effectively. Essentially the problem is that you are trying to put back something that has been permanently deleted, which is the top and bottoms of the waveform. Do you still have a recorded version from before the sound got clipped? If not, you could try the CluipFix effect (in the Effect menu).

Clip Fix attempts to reconstruct clipped regions by interpolating the lost signal. Before use, reduce amplification by 10 dB to give room for the reconstruction. 'Threshold' is how close to the maximum sample magnitude any sample must be to be considered clipped. If processing is slow, select only a few seconds of clipped audio at a time."

There isn't really a problem with dynamic range. The major problem is that it is too loud and has clipped.

[edmund10]

Is there a way to just take down all the highs?

Shouldnt that solve my problem?

[steve]

I'm looking back to your initial post and trying to work out what you actually want.

You say that the OGG file is the "original waveform", but where did that come from? How did you record that?

The main "problem" with the recording is that the overall sound quality is quite poor. Probably the best thing that you can do is to use the Amplify effect (Effect menu) and set the "Amplification (dB)" to -2 (minus two). It will not improve the sound quality, but it will help to prevent it from getting much worse when you encode it to MP3.

Do you really need to convert it to MP3? If not, the best thing that you can do to that recording is nothing. The sound quality damage that is present cannot be repaired. I can't think of anything that you can do to it that won't just make it worse in one way or another.