Topic: Question about 24-bit recording with an R-09

[MSTaper]

Hey guys, I'm going to experiment with 24-bit recording tonight (I normally record 16-bit, 48khz) and I'm wondering what I'll have to do, if anything, to burn this to CD. I heard about "dithering" and I have absolutely no idea what that is, but I'm sure I can learn, provided I can use Audacity to do it. If not, I'll figure something out. Thanks in advance. rWc3523

[dennisrtyler]

http://taperssection.com/index.php/topic,71191.0.html 

[MSTaper]

Thanks Dennis. I figured there might be an FAQ somewhere, unfortunately, I'm too lazy to work. Not to mention I'm supposed to be working!  rWc3523

[MSTaper]

Cool, that doesn't sound terribly difficult. appreciate it!  rWc3523

[Gutbucket]

Well dennisrtyler did what I should have done and found a previous thread while I was typing, but instead of delete al this I post anyway  .

In general, you can make either a 'data' or 'audio' CDR.

You can burn the 24bit files unconverted as a 'data' cd which would be playable on a computer that can playback 24bit files but would not be playble in a CD player.  This retains full audio quality.

To make a 'red-book' audio CD that should be playable in a regular CD player you'll need to convert the 24 bit files to 16 bit files and burn with an audio CD recording application.  That might be taken care of by your burning software, or with an audio editing software (such as Audacity).  In doing so you inevitably throw some information away, but depending on the source material that may not be detectable and there are things you can do to minimize the quality loss.  Using dither is one of those things, see below.

There are two ways to convert the 24 bit files to 16 bit.  The most basic way is to just truncate (throw away) the bottom (think quietest) 8bits.  A better way is to use some sort of dither, which in non-technical speak essentially 'smoothes out' the ragged bottom edge where those bits are removed.  There are different forms of dither and they can sound different, mostly evident when you turn up the volume on the quiet parts and listen to the decaying reverb and the 'space' around the notes.  Audacity has several options for dithering, check the help files.  You can set the options to automatically dither to your output files as you choose.  It's relatively simple.  It's been a long time since I used Audacity but the default dither options are probably fine.

Other things to keep in mind-
The dither stage should always be done as the very last step, after you do any level changing, editing, fading, eq, or anything like that (if you do any of that at all).  Most people will at least adjust the gain if nothing else to make the loudest parts of the recording just a few db's below the maximum level which makes them easier to play without cranking up the volume and also shifts the music 'up the bits' so that when the bottom 8 bits are thrown away you don't loose as much down there.

Hope that's not to technical. There is loads of more detailed info on this site if you do a search and also in the Audacity help files as well as other places on the web.  

Oh yeah, If the recording is something important, you'll probably want to keep the origional 24 bit files.

[MSTaper]

Hey, thanks. Not too technical. I'm trying to learn more about using audacity to improve the sound of my final product. rWc

[dorrcoq]

Russ - I'm pretty sure you can't burn the 16 bit 48 kHz to CD either, so you must have downsampled those, right?  I know I had to do that with your Mule recording which pissed me off.

[MSTaper]

Man, I have no idea. Once I'm done normalizing or amplifying or boosting bass, I just save it as a wave and use CD Wave Editor to track it. Then I burn it with NERO. So you had trouble burning my files? What was the problem?  rWc3523

[dorrcoq]

Well, the CD Redbook specs for audio CD's are:

2 channels of PCM audio, each signed 16-bit values sampled at 44100 Hz

So, 48 kHz isn't supported.  You haven't noticed that?  If you burn it as a data disc and just play it on the computer there isn't a problem, only if you want to play it on a CD player.

It wasn't a big deal, I just didn't realize it until I went to burn the discs.  My computer takes a long time to downsample for some reason, even when dithering isn't required like in this case.

[MSTaper]

Like I said, I'm learning a lot as I co I've been recording in 16-Bit 48khz, playing with it in Audacity, but I have done nothing with the settings. I save as a WAVE file then burn to NERO. All my discs play in my players. It must be magic!

rWc3523

[Brian Skalinder]

It must be magic!

I suspect Nero resamples from 48k > 44.1k during the burning process.  Probably not the highest quality way to resample.

The sticky Audacity workflow thread at the top of this forum should provide details on how to <1> resample, and <2> dither, so your final output files are 16-bit / 44.1 kHz and CD-ready, without Nero performing the on-the-fly sample rate conversion.

For higher quality resampling, you could also use R8Brain Free, noted in the "Where do I find..." thread at the top of the forum.

[MSTaper]

Brian, so I should either be recording at 44.1 instead of 48, or resampling it "by hand" rather than allowing NERO to do it?  Could this have a really noticeable effect on the sound of the recordings? I'm glad I'm finding this out now so I can start doing it the correct way   rWc

[dorrcoq]

Russ - recording at 48 kHz is not the problem (although you might want to do it 24 bit as well).  It's just that anyone who wants to burn it to an audio CD has to downsample it themselves (unless they let Nero do it, and as Brian says this isn't necessarily the best option for quality).  And I'm sure a lot of people aren't aware of this, or know how to do it themselves.

Personally, I use Cool Edit Pro 2 to downsample and/or dither.

[illconditioned]

I don't see the point of doing 24 bit on this recorder.  The specs of the chip inside say the max SNR is 92dB.  That means, the noise floor can be no lower than 16 bits (-96dB).

I verified this.  I put a 1k resistor load on each channel of a miniplug, plugged into line in, and recorded in 24 bit.  If this was a perfect recorder, there should be zero bits of noise.  In fact, the lower 9 bits were noise.  So, go ahead and record in 24 bit, but you'll just be recording 8 bits of extra noise.

AFAIK top notch ADCs will get maybe 18 or 20 bits maximum.  So, 15-16 bits is not bad.  It just doesn't warrant recording in 24bit.

  Richard

[MSTaper]

OK guys, I'm learning as I go. I'll get back to y'all later on. Got to get to a show. This just shows that I'm still new at this. Constructive criticism is alway welcome. Russ C.