Audacity Forum

Hi,

I have some audio that has really low volume, but I want to increase the volume in the .mp4/.mkv files I store them in. However, when I do amplify enough to get the desired volume, the whole audio waveform looks very weird. But, the voices don't sound distorted.
I have seen other audio clips that sound as loud as what I want, but their waveforms look like my audio before it was amplified.

Here is a screenshot. The top is the amplified version and the bottom is the original. Any ideas?
Thanks in advance!

<<<I want to increase the volume in the .mp4/.mkv files I store them in.>>>

You won't be doing that in Audacity. Audacity always converts your show to a high-quality internal format for editing and then Exports a whole new file. This is very nice for editing, but messes with you if you have compressed format originals. The compression and it's damage doubles.

That and you need Audacity 1.3.12 and FFMpeg to natively recognize those types of files at all. That could be why Audacity applied Amplify wrong. It didn't really know what it was doing.

Did you have "Allow Clipping" selected when you applied the Amplify tool?

Koz

Thanks for the response.

I actually used AviSynth to do the Amplification...
If I don't allow clipping, the audio is too quiet...

I guess my question would be: does clipping actually cause the audio to be degraded at a real level? I don't notice the difference really.

AviUser wrote:does clipping actually cause the audio to be degraded at a real level?

Yes, clipping is a severe form of distortion. With most types of sound the distortion is very obvious and unpleasant.

So, is there any solution?

Wait, so when I put the higher volume on my laptop, the audio is distorted??

Amplify to 0 dB, and if it's not loud enough, increase the playback volume of your sound card or speakers.

Note that if there are any very loud clicks on the track, then that could cause the amplification to be less than otherwise. If the waveform still looks small after amplifying, check the waveform carefully and find where it is reaching 0 dB - if it is due to a click, then fix the click and amplify again.

Okay, thanks for the information.

I guess the best thing to do is amplify as much as possible without clipping (with exception of some loud clicks).

You may need a couple of rules. In Audacity, Amplify and Normalize are sisters of each other. They increase the size of the waves until one sharp peak wave somewhere in the performance touches zero. If someone fires a gun or drops a bottle on the floor in the performance, then that sound will take over and everything else will be lower than that.

Neither tool will change the character of the performance -- suppressing the gunshot, for example. Amplify works with one high peak. Normalize treats left and right as separate shows.

I do wonder about what you're expecting. The show with the massive blue waves should have been plenty loud. Yes, the "before" show would have been seriously quiet.

If you can stand remixing the show with a dynamic compressor, you can make a serious difference in the loudness without smashing the waves into zero. These tools simulate somebody riding the volume -- turning up the low parts and turning down the high ones as the song plays. Chris's Compressor is a grand master at this.

http://pdf23ds.net/software/dynamic-compressor/

He designed the tool so he could listen to opera in the car. It does an amazing job of reordering the loudnesses in a show.

Koz

Thanks, that program looks nice.
But, I think I'll stick with no clipping amplification and just use my speaker's volume.