session files change to wav from mp3 without my intervention

Report · Jul 16, 2017

I start out with mp3 files and then make a session.

Audition asks me to move the files I am using into

the inside sessions folder, but the files change

by themselves into much larger wav or aiff.

Why do I want that and can I keep them as mp3?

2017.1.1 build 10.1.1.11

Thanks anyone

Report · Jul 17, 2017

You don't want to keep your files in MP3 if you're going to be editing them. Audition (and every other DAW I know) works internally with wave files and there are good reasons for this.

MP3 is a very lossy compressed format and each time you convert to wave then back to MP3, the signal is re-encoded with more MP3 artefacts and distortions being added. You can often get away with two of three of these stages unless you listen carefully and compare your work to the original--but you soon reach a point where the quality falls off a cliff and starts to sound horrible.

Why don't DAWs like Audition work natively with MP3 files? Well, MP3 is a by-product of MPEG video coding--the full name is MPEG 2, Layer 3. As such, the sound isn't stored as a continuous series of samples, rather, it's fed a frame at a time and reassembled by your decoder. This makes accurate editing and most effects impossible to do with MP3 files. You will find some MP3 editors online, but they limit you to level changes and very rough time edits.

MP3 is designed as a distribution format only, not for use in production. Once Audition has converted to wave for you, you're best off staying that way through all your processes and only converting a finished edit/mix to MP3. Even then, I keep a wave copy of my finished work before making an MP3 version.

Report · Jul 17, 2017

the full name is MPEG 2, Layer 3.

Being pedantic I think it might be MPEG 1. Layer 3

Report · Jul 17, 2017

https://forums.adobe.com/people/Richard+M+Knight wrote
Being pedantic I think it might be MPEG 1. Layer 3

Being properly pedantic , it's both, as the definition was officially extended from 1 to 2. The correct title is either MPEG1, or MPEG 2 layer III which is of course incorrectly abbreviated to MP3.

Report · Jul 17, 2017

Report · Jul 17, 2017

etc...
MP3 is designed as a distribution format only, not for use in production. Once Audition has converted to wave for you, you're best off staying that way through all your processes and only converting a finished edit/mix to MP3. Even then, I keep a wave copy of my finished work before making an MP3 version.

Thank you Bob Howes, these are the answers I like.

altho how come the wavs are so much bigger?

Report · Jul 17, 2017

Basically because mp3 is a lossy compression method. So whilst a .wav file contains all the audio information a lot of it gets thrown away to make the compressed .mp3 file.

Report · Jul 17, 2017

Strictly speaking, what happens is a masking process. The audio is split up into 15 'critical bands', and quieter sounds, which are perceived to be less audible in a band have their coding bit depth reduced - this is known as a 'coding gain', and that's where the space saving comes from. The degree to which this process is applied varies with the allowed data rate, so 128k MP3s have a lot of masking, and the higher bit rate ones have less, and accordingly sound better.

Report · Jul 17, 2017

You're both correct but MPEG 1 never really caught in in professional operations. I know that when I was converting our satellite transmissions to digital. We weren't willing to do that until MPEG 2 was available.

Either way, the basics of why not to use MP3 as a product format hold true.