Exporting 32 bit float files: dither or not?

Audacity 3 Help Forum Windows
1

I have a raw recording in 32 bit float,
and I want to get this into clickrepair.
I ‘export’ the raw recording to the ‘my music’ folder as 32 bit float, so as to not lose any quality.

Do I need to select NONE for dither since I am not down-coverting?
Right now it’s all on default, so the ‘High Quality Conversion’ has ‘shaped’ for dither.
Does that mean low level noise is being added to the 32 bit file even though it’s being saved as 32 bit file on my PC?

I’ll then run it through clickrepair, send it back to Audacity for edits,
and THEN I’ll dither when ‘exporting multiple’ because it’s down converting to 16 bit.

But when exporting that raw 32 bit file first,
do I need to select NONE for dither? Or does it matter?

THanks

2

It appears dithering is only applied “when converting to a low bit depth”, according to the dither audacity web page.
Carry on. :smiley:

3

Don’t worry about dithering.

Audacity handles it correctly and graciously. If and when it’s needed, it will be applied.

I don’t know if exporting as 32 bit float is needed. If you do all your processing in Audacity, you don’t need to export, I’d think. But maybe I don’t understand what you’re doing exactly.

The industry standard for exchanging files to work on, is 24 bit wav. Either 44.1 KHz or 48 KHz for video. And some people like higher sample rates, cause some plugins seem to sound better. Of course, that’s in the way the artifacts are formed and recording at 96 or 192 KHz might just push them out of the audible range.

If the export is only for listening, 44.1 KHz, 16 bit is sufficient. And if you need to email the song for listening, you could use a higher bitrate mp3, let’s say 192 Kbps or higher.

4

I’ll then run it through clickrepair, send it back to Audacity for edits,
and THEN I’ll dither when ‘exporting multiple’ because it’s down converting to 16 bit.

If this is digitized vinyl there is plenty of noise already and no need to dither. :wink:

5

What do you mean?
Isn’t this a practical workflow?

Record, export, clickrepair, import, normalize, split tracks, then export as 16 bit for cd burning?

6

DVDDoug is a vinyl hater – you can safely ignore 90% of his ramblings on the subject or its fidelity or lack thereof :smiley:

Hyperbole aside, it is reasonable to assume that statement was made with his tongue firmly wedged into his cheek.

7

Yeah I figured that out after a few minutes.
Haha its all good.

OK so which workflow is better:

  1. Record in 32 bit, export 32 bit for clickrepair and import back in to Audacity for edits, then export to 16 bit for CDs.
    or
  2. Record in 32, export as 24, repair, import, and edit, then export as 16 for CDs.

1st option is dithering once, 2nd one dithers twice. Right? Does it really matter?

8

Record, export, clickrepair, import, normalize, split tracks, then export as 16 bit for cd burning?

That’s right. Audio CDs are 44.1 kHz, 16-bit, stereo. At some point it must be converted to 16-bits.

And yes, it’s “standard practice” to dither when downsampling, even though you can’t hear dither (or the effects of dither) at 16-bits or better under any normal/reasonable listening conditions.

Since you normally can’t hear dither, it’s not something I worry about. Have you ever listened to a CD or MP3, and thought, “it sounds like they forgot to dither”, or “I think they used the wrong dither algorithm”? …I like to focus on things I can clearly hear (such as clicks & pops and other background hiss & crackle, and the poor frequency response of older records, etc.)

1st option is dithering once, 2nd one dithers twice. Right? Does it really matter?

If you are going to dither, dither once when you downsample. If you dither more than once you are adding noise more than once.

But as you’ve said, dither is noise and there is already noise on a vinyl record. Adding more dither noise isn’t likely to help anything, but since the dither noise is so much lower than the existing vinyl surface noise it’s not likely to hurt either.

DVDDoug is a vinyl hater – you can safely ignore 90% of his ramblings on the subject or its fidelity or lack thereof > :smiley:

:smiley: :smiley: Truth!!! I grew up with records, and I always hated the “snap”, “crackle”, and “pop”. And, I hated the fact that they deteriorated no matter how carefully I tried to care for handle them.

And back in the vinyl days the overall “sound quality” wasn’t that good, at least for most popular/rock records. Classical records had a reputation for better quality, but I wasn’t into classical. There were good-sounding records by Pink Floyd, Fleetwood Mac, and a few others, but most were just mediocre.

9

Don’t forget though about the bug Exporting from integer internal formats to files in same format or higher adds unwanted dither noise.

That is not too much of a problem though, given the Audacity default is 32-bit float storage, and assuming any imported files are imported at 32-bit resolution per that default. When importing using FFmpeg some formats are only imported at 16-bit.


Gale

10

Me too!
That’s why I don’t buy VG records :smiley:

11

So this doesn’t apply to exporting 32 bit to either 32 bit or 24 bit?

12

It depends on the music. You can hear dither in headphones in very quiet classical music. When Audacity dither was too loud a few versions ago, lots of people heard the dither in all types of music.

Dither does help prevent harmonic distortion which would otherwise be there when downconverting. You can hear that distortion too if you downconvert enough times, but you will probably hear that more than you’ll hear accumulated dither iterations.


Gale

13

There’s a bit of confusion here. You don’t record in 32 bit. The only reasonable choices are 16 or 24. None of us has hardware that is capable of 32 bits.

32 bits floating is Audacity’s internal format. Once your recording lands in Audacity, it’s up-sampled to 32 bit automatically.

or
2. Record in 32, export as 24, repair, import, and edit, then export as 16 for CDs.

1st option is dithering once, 2nd one dithers twice. Right? Does it really matter?

You record in 24 bit, at a sensible sampling frequency of your choice.

After recording, I immediately store an archival copy at 24 bit, 44.1 or higher if needed.

I import the archival copy in whatever I work with atm. Most audio editors and DAW’s are non-destructive and if used properly, will leave the archive copy alone after import. In Audacity, the import is cut up in small fragments (.au files) and there’s an .aup text file that contains the logic to stitch them back together. All in 32 bit.

Whenever I get to a result, I make a 1.0 copy, again in 24 bits.

Finally, when it’s finished, I export the final version in 24 bit and the “output” version in 16 bits, 44.1 or 48. Or even mp3 if it’s just for background theater stuff that’s played on an mp3 player anyway.

I never use FLAC, for compatibility reasons. If needed, I zip wavs. The result isn’t as small as with FLAC, but usually it avoids cutting the wav file in pieces for mail, fi.

Dithering only plays when down sampling. Having a “universal” archival format, avoids downsampling until it can’t be avoided. In te last step. And when I’m there, I don’t worry about dithering.

There’s a comparison out there on the net, with beautiful graphics of DA’s and dithering and phase behaviour and linearity and stuff like that. The only thing that it makes clear, is that you shouldn’t worry about it, because the audible effect is minimal and far, far less than downsampling to mp3, fi.

Usually, I don’t even save Audacity projects at all, as I might continue working with the audio in Final Cut, fi.

14

Most record grading schemes don’t take blemishes into account that were there when the record was new. It always annoyed me that if I bought a “Near Mint” record it could have a huge whacking bubble that would sound far worse than a light scratch of the same length.

That apart, you should not blame the vinyl format for the fact that people did not take care of them.

CD’s can sometimes only last a year or two even if well stored. If I must have a CD of something, which is rare, I rip it to WAV and sell the CD on as fast as possible. LP’s last longer than CD’s - fact. :wink:

I have hundreds of LP’s from the 50’s and 60’s - admittedly classical - where you would have to strain to hear the slightest random noise. Yes, there is some “motion noise”. Some of us prefer that to the sterile silence on a CD that takes so much else away.


Gale

15

OK I’ll try to be more clear.
Afer I’ve made a recording in Audacity,
and I’m going to export the file to my PC,
should I choose:

  1. 32 bit float
    or
  2. 24 bit (under 'other uncompressed files).
16

The bug does not apply when exporting from a 32-bit float project to 32-bit PCM or 32-bit float.

Exporting from a 32-bit float project to a 24-bit file should apply dither. Testing that may be hard. See http://bugzilla.audacityteam.org/show_bug.cgi?id=22#c12.


Gale

17

If the app you in which you want to process audio accepts 32-bit float or 32-bit PCM, export to that. There would be no advantage other than size or speed in exporting to 24-bit.


Gale

18

“under recommended storage conditions, CD-R, DVD-R, and DVD+R discs should have a life expectancy of 100 to 200 years or more;”

If that is not long enough, you can make bit-perfect copies of your CDs periodically. (http://www.exactaudiocopy.de/)

Not all CDs have “sterile silence” between tracks, For example, in the 1982 recording of Mahler’s 2nd symphony by the American Symphony Orchestra, conducted by Gilbert Kaplan (2 CDs), the room ambience is present through all “silences”. Personally I prefer to hear room ambiance than “motion noise”.

19

Clickrepair accepts 32.
I think I’m set. For now.

This has been a really strange learning experience… Never has the idea of “the more you know, the less you know” been more apparent than with recording in Audacity.

20

That is just marketing hype, Steve, or they tested with CD’s untypical of products actually on the market. A bit like that German car manufacturer, perhaps. See Disc rot.

Presumably a digital recording? A good, original LP issue of an analogue recording will give you even better “room ambience” IMHO (as well as some “motion noise”).

Anyway, just inserting some “balance” into the argument. Everyone should use the medium that gives them the most musical satisfaction. :wink: And look after it according to the limitations of the medium.


Gale