Changing sample rate in the middle of a project ?

[chapelier fou]

Hi there,
i started to record a new album a few months ago. i recorded some takes that i really like, so i won't record them again. I was using 44.1kHz/16bit. But i want to go back working on these songs, record new parts, etc. I'd like to use 48kHz/24bit to take benefit from my new soundcard and microphones. Could it lead to some problems ?

thanks !
louis

[trevox]

I wouldn't change from 44.1 to 48 as there really is not that much of a difference. And because the ratio between the two sample rates is not a factor of 2, 4 etc.., you would need to ensure you are using a really good sample rate converter - some (even ones you think might be great applications) are not particularly good at this function. And you may end up re-sampling back to 44.1 anyway if you wanted to put it on CD!

If you plan on doing further processing to the sound, I would suggest you change the bit rate to 24 bit though. While this will not make your original recording any better, as your plugins will be processing the sound at this higher bit rate, it should lead to better post processing audio. There should be no adverse effect doing this either with most applications as the ratio is 1 to 256.

Hope that helps...

[tecgen]

I'd like to use 48kHz/24bit to take benefit from my new soundcard and microphones.

I wouldn't record in 48khz, because then Live would need to interpolate your recording by converting the samplerate to 44khz. I am pretty sure you can hear it when you are going from 48khz to 44khz. Why not simply recording in 88khz? It's double the samplerate of your project and Live can simply convert it to 44khz by dividing by two. Means, no alias.

I suggest recording in 24bit rather then 16bit, simply because then you have enough headroom and do not need to care so much about leveling the input signal.

[chapelier fou]

So basically, i should stick to 44.1kHz but i can change to 24bit without any problems ? (so, end up having a mix of 44.1/16 and 44.1/24 files in the same set)

[trevox]

You could re-sample your existing 44.1/16 audio files to be 44.1/24 too. But essentially, yes that would be my approach.

[tecgen]

So basically, i should stick to 44.1kHz ...

Yes, or 88.2khz or 176.4khz

...but i can change to 24bit without any problems ?

Yes. Internally Live computes always with more than 16bit. With 24bit you simply have more headroom and your are able to record high quality with lower input levels. With 16bit I suppose to record with a max. level near 0db.

8bit = 2^8 = 256 different levels to store the volume of a signal at one sample
16bit = 2^16 = 65536 different levels ...
24bit = 2^24 = 16777216 different levels ...

The higher the bitrate the better

[chapelier fou]

Thanks. i know all this stuff pretty well but when it comes to real songs i freak out and cannot think peacefully...

[ian_halsall]

I would go with 32 bit and stick with the 44.1.

Even more headroom - slightly bigger files but disk is very cheap of course.

But worryingly I just checked my live 9 settings and it's set to 24 bit.

So it looks as though the bit depth was not carried over from live 8.

[ikeaboy]

I would go with 32 bit and stick with the 44.1.

Even more headroom - slightly bigger files but disk is very cheap of course.

But worryingly I just checked my live 9 settings and it's set to 24 bit.

So it looks as though the bit depth was not carried over from live 8.

I'm pretty sure live is always internally at 32bit. You can set recordings to be at 16 or 24bit but even frozen files will be 32bit until flattened.

[ian_halsall]

But you can set your files to 32 bit.

Internally it's 64 bit for 64 bit and 32 bit for 32 bit!

[Tone Deft]

Thanks. i know all this stuff pretty well but when it comes to real songs i freak out and cannot think peacefully...

exactly.

for all we talk about the theory of sample rates and bit depths how often have we actually had problems with them? the regulars around here know the theory, lets skip that small talk. why not make a project where you purposely break all those conventions to see just how bad things sound if you exercise Live's SRC (leave it in hi-Q mode, or not!) and change bit depth.

you're not really going to notice.

[Tarekith]

My own $.02:

- Leave everything as 44.1kHz, there's no benefit at all working at 48kHz unless your final output is for video and that's what they want the audio delivered in.

- IT DOES NOT MATTER if the sample rates are even multiples of each other or not when it comes to sample rate conversion, that's an outdated myth. Even the crappiest SR conversion is likely oversampling the audio many, many times when doing the conversion, negating any 'benefit' of even multiples of SR.

- I personally think Live's SR conversion is one of those things that leads some people to think Live sounds worse than other DAWs. It's working on the fly and is not a accurate as some of the offline options. I'd always work at the destination sample rate when working in Live, and definitely NOT change that mid-project. Unless you're converting the files offline in another app that is.

[ikeaboy]

But you can set your files to 32 bit.

Internally it's 64 bit for 64 bit and 32 bit for 32 bit!

I 32bit mean internal audio routing not 32/64bit programme operation which afaik is different. Live 64bit does not give you double head room, for example, it allows you to address more RAM.

[Armoured Snowflake]

This is an issue however if using a Fractal Axe-Fx to record guitar tracks as it only records in 48khz and not in 44khz. I have the same issue as I recorded my drums and synths in 44 and now have to convert them if I want to be able to track the guitars in Live.