Changing bit depth in a session
 

Hi,
I have a question about bit depths in a session. I always want to check the wav and mp3 exports of my sessions. I use 32 bit floating in composing ,mixing and mastering stage. Then I export to 24bit wav (16bit if it is for cd) and mp3 (16bit).

According to manual "You can change the bit depth for all newly recorded or imported (and converted) files in the session by selecting a different Bit Depth option in the Session Setup window."

I suppose a session can handle multiple bit depths, but I cannot find anything on that in the manual or internet (maybe I do not search correctly :-) ). So I just want to ensure that when changing the session's bit depth while working on them it keeps the old clips in the initial bit depth and imports the new files in the changed bit depth.

I always want to check metering to the new exports with izotope insight 2. I do that mostly to check the mp3 version as it is the most common type of file in digital music world, so I want to be as good as possible. Also I'd like to ask what kind of conversion does the Pro Tools to an imported mp3 file. Does it affect the sound?

Re: Changing bit depth in a session
 

Use Save copy in, check copy audio files and specify the new bit depth

Re: Changing bit depth in a session
 

that's correct.

fyi, if you're recording audio there's never any reason to use 32-bit float; your convertors aren't capable of giving more than 24 bits (if that). switch to 32-bit when printing processed files and/or mixes. when importing, likewise choosing anything greater than the bit depth of the source doesn't give you better audio quality... but it does create larger files...

Re: Changing bit depth in a session
 

Yes, your understanding is correct. Old files stay the same and new files are at the new bit depth. There's zero issue mixing bit depths in a session.
When you import an mp3 into Pro Tools that is the same sample rate as your session, if you use "Add" with no SRC, the file is unchanged. Pro Tools can handle mp3s as mp3s directly. If you select copy with SRC, then you are creating a new file that will be at the current bit depth setting and sample rate (and be the format of your session and this "copy" file will not be an mp3: BWF/WAV or AIFF).

The conversion from mp3 (lossy) to WAV/BWF/AIFF (all linear PCM formats and lossless) is direct. Nothing is added or subtracted from the sound. It is what all mp3 playback devices do for actual playback (they have to decode to linear PCM.)

Re: Changing bit depth in a session
 

I appreciate all of you for your answers. You were very very helpful

Re: Changing bit depth in a session
 

I tried to import mp3 directly (same sample rate as my session) to a session but the add button is staying grey when I choose an mp3 file and cannot use it. I use 2018.4 edition on windows 10. Maybe is it newer addition or have I to check something I cannot find on preferences?

I really tried about an hour to figure it out before asking again.
Thank you very much