Audacity Forum

Had so many questions, so I decided to register and ask you people

I have been editing music for several years now, and recently discovered that, in order to maximize quality, up-converting (bits, samples) is required before amplifying. However, should I upconvert before I normalize? Would that make a difference?

I am pretty sure OS and Audacity version does not matter here.

Audacity converts everything to internal format. It's whatever sample rate you picked in preferences (44100, 48000) and 32-Floating bit depth. A very common Export complaint is the slight noise that Audacity generates when it converts from 32-Float back to your desired output format. So I probably wouldn't bother to convert anything before importing. It will just be extra work for no noticeable gain.

Koz

KlarkKentThe3rd wrote:in order to maximize quality, up-converting (bits, samples) is required before amplifying.

By default Audacity will convert WAV files to 32 bit float format on import, which allows amplification to be performed with extremely high precision.
Processing in Audacity is always in 32 bit float format so it is best to stick with the default 32 bit float format so there is only once conversion back to integer format (probably 16 bit) when you export.

What I am talking about is applying effects to 44100 or 37800 hz files. Should I upconvert those before adding effects?

Who said you should upsample before amplifying?

Resampling sample rates (leaving pitch and tempo unchanged) up and then back down (assuming you want to export at the original rate) is lossy in absolute terms.

Why would you want to do that?

By the way some players may not play files at 378000 Hz (it's a very non-standard rate). That may be a better reason to resample that file.


Gale

Gale Andrews wrote:Who said you should upsample before amplifying?

Resampling sample rates (leaving pitch and tempo unchanged) up and then back down (assuming you want to export at the original rate) is lossy in absolute terms.

Why would you want to do that?

By the way some players may not play files at 378000 Hz (it's a very non-standard rate). That may be a better reason to resample that file.


Gale

I know the first part. But, will up-converting sample rate be a good idea before applying an effect? Like, 44100 to 96000, apply edit, back to 44100. I came across an article about a year ago that was all about how effects programs will inevitable make mistakes, and if the rate is 96000, those mistakes will be very small, and virtually disappear if you down-convert.

KlarkKentThe3rd wrote: will up-converting sample rate be a good idea before applying an effect? Like, 44100 to 96000, apply edit, back to 44100. I came across an article about a year ago that was all about how effects programs will inevitable make mistakes, and if the rate is 96000, those mistakes will be very small, and virtually disappear if you down-convert.

No, that article is wrong. For amplifying there is no benefit in upsampling before processing. There may be benefits for some processes such as pitch stretch effects where aliasing distortion could be an issue, but no benefit for amplifying.

steve wrote:

KlarkKentThe3rd wrote: will up-converting sample rate be a good idea before applying an effect? Like, 44100 to 96000, apply edit, back to 44100. I came across an article about a year ago that was all about how effects programs will inevitable make mistakes, and if the rate is 96000, those mistakes will be very small, and virtually disappear if you down-convert.

No, that article is wrong. For amplifying there is no benefit in upsampling before processing. There may be benefits for some processes such as pitch stretch effects where aliasing distortion could be an issue, but no benefit for amplifying.

Thank you so much; now I know a little more.

However, there is one thing I don't quite understand: if any 16 bit .wav file is automatically converted to 32 bit on import, and then back to 16 on export, will the end file be identical to the original, if no edits were made? I am just terribly paranoid about preserving original sound of all my files.

KlarkKentThe3rd wrote:if any 16 bit .wav file is automatically converted to 32 bit on import, and then back to 16 on export, will the end file be identical to the original, if no edits were made? I am just terribly paranoid about preserving original sound of all my files.

If you want the exported file to be the same as the imported file in that hypothetical case, you will have to set Dither to "None" under "High-Quality Conversion" in the Quality Preferences.

There is some information about Dither (and why you might still want to keep it on when downsampling the bit depth) here:
http://wiki.audacityteam.org/wiki/Dither .




Gale

Gale Andrews wrote: If you want the exported file to be the same as the imported file in that hypothetical case, you will have to set Dither to "None" under "High-Quality Conversion" in the Quality Preferences.

There is some information about Dither (and why you might still want to keep it on when downsampling the bit depth) here:
http://wiki.audacityteam.org/wiki/Dither .
Gale

That article is quite confusing to someone who doesn't know much about audio (me).

"Exporting a 16-bit track to 16-bit with dither set to "none" will be lossless."

But wasn't it said earlier in the thread that .wav files are always converted to 32 bit? If that is true, you cannot export 16 to 16, since automatic up-conversion has been performed on import.

I am very confused here.