Amplify - is it "auto"?

[golfgal]

I'm doing some transfers that have slightly low volume from the source and wanted to optimize the levels for publishing online.

I note that when using the Amplify parameter it seems to automatically select a level (see before/after screenshot) - and the OK button goes away if exceeded that amount.

It seems pretty straightforward that the Amplify effect believes this is the "most" your track should be raised to achieve optimum level.

99% sure that's it - I only wanted to confirm this before doing a whole ton of files.

BONUS QUESTION - to apply Amplify to many individual files it seems possible to use - Apply Chains? However when I tried it seemed like it was going to only use the last value - and not do it automatically. :-/

Screen Shot 2021-01-22 at 10.41.35 AM.png

[DVDdoug]

Audacity has pre-scanned your file and Amplify will default to whatever up or down adjustment is needed for normalized ("maximized") 0dB peaks.

You don't have to accept the default and you can enter a positive or negative number. You can go over 0dB if you allow clipping, and Audacity itself won't actually clip. But the DAC can clip if you play it at "full digital volume", and some file formats (such as "regular" WAV files or CDs) are hard-limited to 0dB. (Its "bad practice" to release/produce a file that goes over 0dB.)

However, the peaks don't correlate well with perceived loudness so if you normalize all of your files they won't all be equally loud. And since this is linear volume adjustment to the whole file (or the whole selection) it only takes one peak to limit the whole file (or the selection).

You can use the Loudness Normalization effect to set or match loudness but you have to be careful not to push your peaks into clipping (distortion when you try to go over 0dB).

for publishing online.

All of the popular online services (YouTube, etc.) do their own loudness matching but they don't all use the same standard. But they won't boost the audio into clipping so some files will still sound quieter than others. Many songs/tracks are already normalized/maximized so they can't be boosted without clipping, so they choose a loudness that reduces the volume of most files and there are only a few that can't be boosted enough without clipping.

ReplayGain and Apple's Sound Check work similarly, reducing most songs to match the target loudness.

[steve]

It seems pretty straightforward that the Amplify effect believes this is the "most" your track should be raised to achieve optimum level.

By default the Amplify effect will amplify to a peak level of 0 dB. That's the highest possible level for most audio formats.

Many users (including myself) prefer to leave a bit of headroom in the exported file by amplifying (or "normalizing") to a little below 0 dB.

[golfgal]

Thank you Doug and Steve!

This is what I figured - however when I try to Macro with Amplify - it seems as if it doesn't adjust *per track* it only goes with the very first recalled setting and applies it to all.

What I'm hoping to find now, is a macro ability to batch "auto" adjust levels to 0db (or just under) across a list of files. Each time, manually one by one Effect/Amplify works fine - but if I create a Macro the value becomes a fixed number (as opposed to automatically finding 0db.)
Macro Parameters Value example - AllowClipping="0" Ratio="1.4313637" - where that ratio seems to remain fixed across all files.

Screen Shot 2021-01-22 at 12.49.05 PM.png (361.31 KiB) Viewed 124 times

[steve]

when I try to Macro with Amplify - it seems as if it doesn't adjust *per track* it only goes with the very first recalled setting and applies it to all.

That is correct. It amplifies by the set amount (adds that amount of dB to each track). This is because macros apply effects without their graphical interface (GUI).

Also, if you select multiple tracks and apply the Amplify effect (in the normal way), the Amplify effect applies the same amount of amplification to all tracks.

What happens when launching the Amplify effect manually is that the GUI automatically adjusts the default amplification amount. When run in a macro, there is no GUI, so no automatic adjustment - you will always get the amount that is set in the macro.

If you want to amplify up to a specified level in a macro, use the Normalize effect instead.

[golfgal]

Awesome - thanks again Steve!