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.

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...duh

Kapt.Krunch

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.

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
duh

MP3 _can't_ be "mastered" because it's not a master format (and neither is CD-R)!

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.

Cheersø,
Laarsø

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

mp3 encoders remove the [[url=http://[/URL]="http://en.wikipedia…"]masked content[/]="http://en.wikipedia…"]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.

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

dzara, post: 391012 wrote: 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.

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

Here is another little trick I've used when presented with 128 kb per second MP3's. At 128 kb per second, your high-frequency response cuts off at 15 kHz. You can easily see that on a spectrum analyzer display in software. It's always quite obvious. So you are losing that top octave. So here's a crazy little recipe.

Much like your separation spectral processing, you can take that concept a step further. And here's what you do. You high pass filter everything below 1 kHz. This then leads you with a recording that sounds like a tin can. You then take that tin can track and within the software, you raise everything up one octave without changing the speed. This creates a real wacko sounding track. You then carefully mix in this wacko sounding track to the original track. In effect, you are creating huge second harmonics that will then also replace what has been lost beyond 15 kHz. It's sort of like and akin to a home witches brew of the original APHEX aural enhancer. It will give you all of this extended high-frequency gobbledygook that has otherwise been lost. But you have to go easy on it. You may also want to experiment with that 1 kHz bandwidth and move it up to 3-5 kHz. Then when people look at it on a spectrum analyzer, it will go clear out to 20 kHz and beyond depending upon your sampling rate.

APHEX or effect? That is the question.
Mx. Remy Ann David

Note that Aphex doesn't rely on transposition, but on distortion to create harmonics.
Can this witches brew sound good enough for a mastering application?
Using a good recipe with rotten food, can't produce anything good IMHO.

Laurend: You can't make the food taste good but you could make it edible (barely). I did it once way back when people still sent out PK's the old fashioned way (by mail). I had a deadline and the 128's were the only source I had to work with. It worked and I had a great tour as a result.

Remy: Kind of funny everyone talks about stepping outside the box and it's two old gals that not only step outside the box but JUMP outside it.

I can't believe the guy from France would tell me this wouldn't work when they eat snails in garlic butter? And how can you accept bleu cheese as a dessert? Though I think that quiche could be an old cliché? I mean a cheese and egg soufflé is nothing more than pizza. Just no tomato sauce or anchovies. Maybe anchovies? So what I was doing was not a transposition but an addendum into the land of second harmonic distortion. And that's musical sounding. A Frenchman should know that by what Ravel did. Ravel essentially created modern symphonic music. French is the language of love and second harmonics are also. Instruments wouldn't be worth listening to without second harmonics. We can re-create and generate most anything today in software and it all works. If it didn't, we wouldn't have ProTools even though I don't care much for ProTools I utilize nothing but Pro Tools. So if you get in your Renault you'll Re-know it ain't a Mercedes. Even though it also has four tires.

As I was traveling through North Carolina on my way home from Nashville, I saw a company called Baggette that was in the grain business. But I don't think they made any French bread? What's with that? Just give me a Baggette, a chunk of cheese, a bottle of wine sitting on the side of a hill watching the sunset and I'm happy.

I like a lot of garlic in my butter with the snails.
Mx. Remy Ann David

Next time your in Nashville honk your horn on 440 (back yard is bordered by 440). I'll throw you a real Baggette. Making bread is a hobby of mine.

@Remy,
Mp3 can't be used as the real thing. You can try every possible processing solution, some Cheez Whiz can't be transformed into real cheddar.
PS: I dislike snails :)

Well perhaps you are not a broadcaster like myself? If you were, you'd realize that compromise is not a dirty word. No, MP3's don't sound like uncompressed wave files. But if it's all you had to work with what would you rather do? Starve? Or do the best you could with what you had to work with? That's the mark of a true professional. Not everything comes from the land of milk and honey and snails. Just how did France end up with so many snails? And who was that crazy person that ate the first lobster? They must've been starving. I mean, if you just try to bite into one, you'll break your teeth. But if you can get beyond its imperfect world on its hard shell, you'll know what goodness lies within. And the same thing can be said for substandard MP3's. Because a great recording and a good mix still sounds like a great recording and a good mix in MP3. In fact you get cool little extras like echoes and flanging sounds that I have actually found have worked well with some rock 'n roll recordings. And our people today downloading uncompressed wave files? No they are not. They are downloading MP3's and they are willing to live without Maseratis, Lamborghinis, Aston Martins, Rolls-Royce and Bentley's. Those are the only cars really worth driving. Everything else is substandard. Especially many of those cars from your home country which in my country are generally considered true pieces of crap. So as a professional if you have to work with an MP3 you do it and you do it as best as you can. And that's what I do. You, my friend, are obviously not willing to compromise on anything. Not sure why you take such a rigid stance? Do you work with rap, hip-hop, death metal? In that respect, I won't compromise. I won't work with any of that crap because it's not music. It's a computer game rhythm box and nothing more. So I don't endorse dirt. Other people can. I won't. You don't have to work with MP3's if you don't want to. It's your decision to make. Even George Massenburg would e-mail MP3's for mix approvals. Because you can still hear a great mix and a great recording when you listen into it. I listen to continuity of performance value and engineering expertise. That still comes through with MP3's. So if you don't like snails you probably also don't like sushi? It's amazing how fishy gats when you cook it. When you don't cook fish, it ain't fishy. It's like a rare filet mignon in all its natural splendor. So an MP3 is more like a California roll which ain't in its raw splendor. And it's still perfectly delicious. When I was in France in Granoble & Nice, I lived on snails in garlic butter and fresh bread. Of course good MP3's sound quite a bit better with good algorithms as opposed to poorly designed algorithms. So maybe you just need to sit down with a good Baggette some garlic butter and snails and take in a good MP3?

I'm going for sushi and Chinese food for tonight's dinner. Too bad they don't have any snails in garlic butter. Dammit!
Mx. Remy Ann David

As a rule, never work with MP3!

In my opinion if someone gives you an MP3 to master rather than a Wave, they can't be very serious about their music.

In addition to that it seems a bit odd, I mean what's stopping them from uploading a Wave?
You might want to make sure they are in fact the master owner of the track.

Launch Pad, yeah, rule of thumb, try not to record things in MP3 for your own production purposes. If on the other hand people come to you with their MP3 that they want you to work your magic on, first ask them if they can provide you with an uncompressed file version? Of course that doesn't mean that they didn't do their whole production on a little port-AH digital studio thingy and all in MP3.

No doubt about it, there will always be some kind of audible artifacts in MP3's. Many audio professionals find it completely awful and substandard and they would probably be right. Nevertheless, you work with what you have. There are actually some things one can do when Mastering MP3's to improve some of what has been lost. At the same time you can also over exaggerate what doesn't sound good. And as you can tell this evokes passionate responses. So I think I'll just smoke another bowl and take it all in?

Of course Launch Pad also brings up a good question about accepting clients materials from any of the many freebie services offering such conveniences. I've been doing just that for over seven years now and it's a great way to go. Nobody has to go out and get wet and everybody can be pleased in knowing that they are working towards a more greener environment. In fact it's something we should encourage people to do.

Now I don't quite agree with Launch Pad that someone coming to you with an MP3 can't be very serious about their music. Recording and engineering expertise has nothing to do with one's unique musical talents. And this wouldn't be the first time that someone hasn't gotten successful from something they recorded on a four track cassette studio thingy. Because it all comes down to the performance and the magic.

I just hope my commentary here won't cause Launch Pad to Blast Off? I hope he doesn't have a short fuse? I know that from what Launch Pad was trying to tell you that a better recording could Launch your career which might Rocket you to Success?

Always remember to count down from 10 when you get frustrated.
Mx. Remy Ann David