16-bit files that are edited at 32-bit—Is it OK to reduce to 16 again?

2009-06-02 11:43:32

I am not very experienced in audio processing theory but I would like to learn more about it. So please help me.

The situation

Several years ago hard drives have been expensive and their capacity was limited compared with nowadays. So I made the mistake of compressing recordings (44.100 Hz, 16-bit) of my own compositions into a lossy format (mp3, 320 kBit/s CBR; I don't know whether flac or Wavepack have already exist at that time).

In the meantime I have edited some of those files in Audacity (which internally uses 32 bit as far as I know) and saved this edited files as "WAV Microsoft 32 bit float" for further editing.

My question

In advance some of the edited tracks I have to send to a studio in a lossless format (as test recording only, no editing there) and by no means I want to risk a loss of audio quality once more.

For transmitting to the studio can I nevertheless reduce the 32-bit files to 16-bit (because the source files have not been better) or should I use 32-bit (because Audacity uses it)?

English is not my mother tongue but I hope you will understand my concern, it is very important for me. I would appreciate any suggestions.

Robertina.

16-bit files that are edited at 32-bit—Is it OK to reduce to 16 again?

Reply #1 – 2009-06-02 13:20:44

As long as the studio is not going to do any further processing of the files I would send 16 bit.

16-bit files that are edited at 32-bit—Is it OK to reduce to 16 again?

Reply #2 – 2009-06-02 13:28:42

Edit in 32-bit, when finished, go back to 16-bit.

- Spike

16-bit files that are edited at 32-bit—Is it OK to reduce to 16 again?

Reply #3 – 2009-06-02 14:07:02

It probably doesn't matter either way.

If the mp3 decoder was 16-bit, and you only did cut/paste editing (no EQ, gain, etc), then there will only be 16-bit values in the 32-bit file anyway, and you will lose nothing converting back (as long as the conversion algorithms are correct, and match).

However, there's no harm working in 32-bit, if all software you intend to use supports it properly.

Cheers,
David.

16-bit files that are edited at 32-bit—Is it OK to reduce to 16 again?

Reply #4 – 2009-06-03 01:34:46

Thank you for your answers.

@ 2Bdecided

"If the mp3 decoder was 16-bit, and you only did cut/paste editing (no EQ, gain, etc), then there will only be 16-bit values in the 32-bit file anyway, and you will lose nothing converting back..."

My editing has been more extensively (for example 32-bit VST effects in a 32-bit environment).

Following up your answer my files contain 32-bit values therefore and saving files as 32-bit does not mean a bloat of the 16-bit source files, if they have been edited with 32-bit effects.

Is there an objective method to measure the sound quality difference between the edited files saved as 32-bit floating-point, 32-bit fixed-point and 16-bit?

Thank you for your help again.

Robertina.

16-bit files that are edited at 32-bit—Is it OK to reduce to 16 again?

Reply #5 – 2009-06-03 02:25:24

Question
Let me get something straight, are you converting the 320kbps MP3 files back to WAV 32 bit through audacity??

Answer if so
If you are doing this, I would just suggest you leave it in MP3 because by converting the track to WAV, you will only increase the size of the file and not the quality of it. So it would just be better to leave it in MP3 format, rather than converting it.

If the answer is no and you are using a new 16 bit WAV file that is copied or is your original WAV file from your own compositon then, Converting it to 32 bit would not make a difference seeing that the 16 bit would fit in the 32 bit.

But if you are converting from the MP3, well it wouldn't make a difference quality is already lost and there is no way to get it back, so I would just leave it in MP3 if this is the situation.

Quality would be the quality of the MP3 basically wrapped in a wav file and PCM audio

FElix