Question About Mastering MP3s

[rbf738]

I tell my clients that a rendered wave is ideal but a recent client sent me MP3 files to work on.

Dumb question (I never work with them) but do MP3s have a bit depth? I coudn't find anything so when I went into my DAW to master I didn't know if I should be rendering down to a 16 bit and then when he requested the track to be in MP3 format back to him I didn't know if I should convert it into 128 kbps or if i should go for something higher. He sent the initial track in 128 kbps (ugh I know), should I just convert it back to 128 for when I sent it to him?

[acorneau]

MP3's are usually stated as a bit rate, so a 128kbps file is "kilo-bits per second". I don't know if one could extrapolate an equivalent bit depth and sample rate from that.

When capturing the processed version stay at 24-bit. If the client demands an MP3 as the return format then send him the best you can, usually 320kbps. I make my MP3's directly from the 24-bit files, some people make them from the 16-bit versions.

Good luck.

[Kapt.Krunch]

Anyone with the slightest concern about sound quality would never send an MP3 to get "mastered". (Which, by the way, is term used too loosely these days. I've never "mastered" a track. I've made some pretty good final mixes, though. I just don't have the high-end tools and facility needed to "master".)

Anyway, there is just too much missing in an MP3. When you convert it to WAV, it doesn't get better. It's just a bigger file of "too much missing". There's too little information to work with to get smooth results. An MP3 should be the very last thing anyone ever does to a recording, and only for "convenience" purposes...not for serious further processing, or serious listening.

Any processes you do on it will likely just further degrade it, and introduce new artifacts. Then, it has to be converted BACK to MP3, where it gets even further degraded.

This is kind of like taking your car to a mechanic and telling him you know your spark plugs are completely shot, but you want him to get the car running in top condition using the old plugs.

I'd explain this, and ask him to send you a suitable file to work with. Of course, there's always the possibility that the entire thing was recorded direct to MP3 on one of the handy "record-like-a-pro" portable devices, and that's all he has.

"Master" an MP3? Oh well. Go for it...the earbud crowd will probably never notice, anyway...

Kapt.Krunch

[sue08401]

Years ago I was having trouble with my computer and started to back up files. I had just finished putting the mp3 files on a cd when the computer decided to crash and die. So I was stuck either re-recording the CD or see what I could do with the 128 mp3's on the cd. I ended up with a decent sounding CD by using something like seperation mastering (although that's probably the wrong name).

I started by converting the files to 16/44 wav files. Then I started copying the files for each song and isolating different parts. One copy was eq'd to highlight just the bass. another to highlight the core of the vocal. And I did this for each part. Then I loaded all the files into a project and mixed them (including the original 16/44 file) together. It ended up real close to the original 16/44 files I had on the old computer.

To use Kapt. Krunch's analogy, it's like using the old spark plugs after you've cleaned them up and refurbished them. Not near ideal but it is possible to get a decent finished product. Just let the band know it would be a lot better to work with at least a 16/44 file.

[djmukilteo]

I'm not a mastering engineer, but there are legitimate ones who are in this community here....but I'm pretty sure you don't or can't "master" an MP3....
I think that's just how stupid and crazy this whole "mastering" concept and thinking has gotten out there.
Pretty ridiculous if you ask me!....call it whatever you like I guess....but just saying it doesn't make it so.
Your "client" obviously has no clue so just make it a little louder for him and give it back to him the way you got it...
Seriously

[Laarsų]

The great Wiki explains:

"In lossy audio compression, where bits are allocated to other types of information, the bits actually allocated to individual samples are allowed to fluctuate within the constraints imposed by the allocation algorithm."


Also, only lacquer masters and glass masters get "mastered." Everything else is premastering. Think about it.


Cheersų,
Laarsų


("Do you even know what the fluctuate?")

[Laurend]

mp3 encoders remove the masked content of the audio. Any further processing have to deal with the missing parts of mp3 files. Which means that no pre-mastering can be done without arising severe artifacts. mp3 is definitely not a production format. It's just a loosy distribution format.

[dzara]

I have been mastering music for a long time and never did work with an mp3. I accept wav. or aiff, 16 or 24 bit and 44.100 or above. Go back
and ask for a proper audio file

[Laurend]

I have been mastering music for a long time and never did work with an mp3. I accept wav. or aiff, 16 or 24 bit and 44.100 or above.

I've added the 32 bit float to the list above. It's the best solution I've found to prevent dealing with clipped source files.

[Red Mastering]

that kind of question makes me realize that 'mastering' has came a long way
and we can expect to 'master' smartphone recordings soon