44.1khz, 48khz or 96khz

[jglunt2112]

I currently am using a Tascam 2400 MK2 for recording (24 bit; 44.1khz) and Audacity 1.3 beta for mastering my songs (Windows 7 home premium operating system). Though it records at 24 bit, the Tascam will only export at 16 bit and 44.1khz. I'm using 32 bit float in Audacity for mastering the stereo tracks, but if I try to change the material to 96khz in Audacity, it shrinks the song to less than half length and I turn into the Chipmunks. I have two questions: 1. Is it worth trying to change the material to 96khz when I'm going to be putting it onto CD? 2. If it's worth changing the material to 96khz to master it, how can I accomplish that?...Jim

[kozikowski]

Of course it's best if you had done all the work at the higher bit rates and depths. Whatever sound damage you have is already burned into the music. These are examples:

Depth/Rate Conversion
-- Change Project Rate (Hz) lower left > 44100
-- Track Name > Set Sample Format > 16-bit PCM

Music CD is 4100, 16-bit, Stereo WAV-ish and you can't stop it. So the CD will never be any better than that -- not that it's terrible. It's far better than any download.

32-bit floating is grand for effects and filters because it's very robust. It will withstand extensive sound management and manipulation without serious damage -- given that it was recorded like that. I don't exactly know what will happen if you converted it in post production only to apply the filters.

There is also the dithering thing going on, too. You get background noise every time you convert between bit rates and depths.

Any chance of hearing any of the work?

Koz

[DVDdoug]

Though it records at 24 bit, the Tascam will only export at 16 bit and 44.1khz.

If your hardware has a 24-bid analog-to-digital converter, you should be able to record to 24-bits and export a 24-bit file. But, it shouldn't matter... Whatever analog source you are recording, it probably has less dynamic range than you get with 16-bits.

Some software/drivers will allow you to record to 24-bits, even though the hardware is only 16-bits... But of course, those extra bits are only wasting space and making a bigger file.

I'm using 32 bit float in Audacity for mastering the stereo tracks...

Most audio editors work in floating-point internally. It makes DSP (digital signal processing) easier.

... but if I try to change the material to 96khz in Audacity, it shrinks the song to less than half length and I turn into the Chipmunks.

That's strange. You should be able to export to a different sample rate (or different bit-depth) without problems.

I have two questions: 1. Is it worth trying to change the material to 96khz when I'm going to be putting it onto CD?

No. It's like copying a VHS tape to high-definition Blu-Ray. It doesn't improve the quality, and your CD will be 44.1kHz/16-bit anyway.

2. If it's worth changing the material to 96khz to master it

I'd say no, but some people will disagree. There may be some effects & plug-ins that work better at 96kHz, but that's a quirk of the particular plug-in.

There is always some (tiny) quality loss when you change the sample rate. (i.e. If you upsample from 48kHz to 96kHz, and then downsample back to 48kHz, you won't get the exact-same bytes as you originally had.) This is not the case with bit-depth. You can convert from 16-bits to 24-bits (or to 32-bit floating point) and when you convert-back to 16-bits you'll get your exact-original bytes back. (That assumes you are not dithering or otherwise processing the data.)

Scientists and people who do blind listening tests will generally tell you that 44.1khz, 16-bit is better than human hearing. But, many audiophiles & audio professionals think higher resolution sounds better.

[kozikowski]

... but if I try to change the material to 96khz in Audacity, it shrinks the song to less than half length and I turn into the Chipmunks.

That's strange. You should be able to export to a different sample rate (or different bit-depth) without problems.

It does that if you convert the project in the wrong place. Follow my instructions.

Koz

[steve]

... but if I try to change the material to 96khz in Audacity, it shrinks the song to less than half length and I turn into the Chipmunks.

The problem there is that you are not converting the audio to a new sample rate. You are just forcing the track to play at an increased speed (so that there are 96000 samples played each second rather than 44100 samples each second.

I bet that what you did was to click on the name of the track and, from the drop down menu, select 96000 from the "Select Rate" options. That does not change the sample rate, it just changes the rate that the audio is played back. To change the sample rate you need to resample the track: "Tracks menu > Resample".

Having said that, resampling will not improve the sound quality.
It may be easier to visualise the situation by considering a graphic analogy:
Let's say that you have a scanned image that has been scanned at 150 dots per inch. If you "resample" the scanned image to 300 dots per inch,the quality of the image does not improve - you just have two dots in your resampled image for each dot of your original scan.

[jglunt2112]

Thank you. That's an excellent illustration.

Jim