Audition not saving changes to file

[Cameron22527877lpb4]

I'm trying to make a simple edit to the attached mp3 file by trimming the silence at the beginning, but the file isn't saving. I'm hitting save and the asterisk disappears as if it were saved, but if I close the file and open it again, the space is there again. I've tried "save as" but that doesn't work either.

[Richard M Knight]

 If I open a MP3 I only get the option to 'save as' and I then get  the message 'are you sure you want to overwrite'.

[SteveG_AudioMasters_]

The first thing here is that you can't make an edit to an MP3 file in Audition. To perform any operation at all on one, it has to be decoded to Audition's native format (wav) and when you've made whatever alterations you want, it has to be re-encoded back to being an MP3 again. This is not a lossless process - your file will be degraded. How much rather depends upon the bit rate of the file, but typically 128k files will degrade noticeably in a single pass though this process. So when you re-open the file, you are listening to a file that's been decoded, re-encoded, and then decoded again...

You haven't said how much silence you are trying to remove; it may well be that the encoder is putting it back again. Unfortunately the encoder isn't an Adobe product - it's the Fraunhofer one. There are several things you could try that might help, though. If it's just time you are trying to cut out, you'd almost certainly be better off using something like MP3DirectCut which gets around the decode/encode issue. You really can't do much more with an MP3 file directly though, so if you want to make other changes, that's probably not the route to use. The other alternative would be to re-encode using an app that opens wav files, but re-encodes using something like LAME, which almost certainly won't mess about with the timing. There is a piece of software with a name very similar to Audition that will let you do this. Normally I wouldn't recommend this software, but for this specific purpose it might be able to help you.

[Cameron22527877lpb4]

Thanks Steve. Just to clarify, do you mean that Audition automatically converts mp3s to wav and then back again? Or does that have to be done manually?

[SteveG_AudioMasters_]

The act of opening an MP3 file in Audition will result in automatic decoding - otherwise it simply can't and won't open. How you save the resultant wav file though is entirely up to you.

[Cameron22527877lpb4]

Okay, so if I were to edit an mp3 and hit "save", that automatically results in re-encoding? I've done this sort of thing several times with other files and have never noticed the degradation I'd expect to hear when double encoding an mp3.

Regarding the silence, I'm just lopping off a fraction of a second at the beginning of a sound effect file so it lines up with the action in a video correctly. I got around the issue by opening the mp3 in Reaper and exporting a trimmed version as a wav, but I'm still curious as to why the trimming won't work in Audition.

[SteveG_AudioMasters_]

No - you haven't edited an MP3; You've edited a wav file. If you tell it to 'save as' a wav, then it won't encode anything. But if you tell it just to save, and you have the warning system turned on, then you get this:

And this is because, despite what it says on the file name, it's not an MP3 at this point. Personally I think that this is a little naughty of Adobe - it should make it clear that the file open on the screen is not an MP3.  What it should say is that the file will be re-encoded to an MP3 if you hit Save - and I have to say that this fools a lot of people, who don't realise the implications of the statement as it stands. The 'backup' they are talking about you get when you use the Save As option - and that's the one that saves the file as it currently is. As for whether you can hear the artifacts - that depends very much on the material and save rate; you are far less likely to hear it if it's sound effects.

But that's not all. If you do a Save at this point, you'll rencode that file to an MP3. But what remains on the screen isn't the MP3 you think you've just saved. If you want to hear your freshly-saved MP3, you have to re-open it, whereupon it will be decoded - again. The reason for this is that Adobe want to retain the option to let you save it uncompressed for as long as possible, and to do this the wav version has to be retained and visible.

It's fine to have this convoluted system, but only if it's explained properly, and unfortunately I don't think it is at present - or come to that, has ever been.

As for the silences, that's almost certainly the encoder. There was an issue with this years ago with it cutting off the start of files when encoding, so Fraunhofer automatically adds a bit of silence to prevent this from happening.

Lastly, you have to bear in mind that MP3 was never intended to be a production format - only a distribution one. Most of the stuff that occurs when you use it comes about because of this.

[Cameron22527877lpb4]

Do you know how to turn that warning on? I don't remember ever seeing it, though it's possible I did and turned it off a long time ago.

I do these types of edits with songs as well and don't notice any degradation. That doesn't mean there isn't any going on, of course, but not enough for me to notice. Do you know where the save/encoding settings for that are? I don't see any under preferences.

In an effort to get an answer directly from Adobe, I did a live chat and asked whether what you're saying is true (no offense, I just don't know who you are and don't implicitly trust anyone on the internet). They couldn't give me a straight answer. They said they "thought" that hitting save wouldn't degrade the sound quality, "to their knowledge". When I pressed them for a concrete yes or no, they were evasive. This is the second time in the last couple months I've sought help from Adobe chat and gotten the impression that I, someone who's used their software for about a year, know more about it than the person "helping" me. Frustrating.

[SteveG_AudioMasters_]

Edit>Preferences>General - bottom of the page. You can't alter much about MP3 encoding, but if you select it as an option in Save As, and go to the format settings, what you can alter is available there. Which brings me to another point that quite frankly, I've only just discovered. And that is that since MP3 is out of compulsory licencing now, Adobe have changed the encoder. And it's now LAME. I don't believe that they exactly trumpeted that from the rooftops!

As for whether I'm correct or not about the order of operations - it used to be rather easier to tell, but now they've changed the encoder it's not so easy - LAME behaves a lot better than the Fraunhofer 'official' one did.*

But, I've been using Audition and its predecessor (Cool Edit) for about 25 years, and have been alpha and beta testing it for a lot of that time, and I think that I have a reasonable grasp of what's going on. The people on the help desk, though, don't actually use it at all. They just have crib sheets to go on, so it's hardly surprising that they are a bit reluctant to commit themselves so something that normally, they'd send over here for us to answer anyway... because when they say 'to their knowledge', basically it's pretty limited. You have to cut them a bit of slack though, as they have to be able to answer questions on the entire range of Adobe software, so it's hardly surprising that they don't specialise in any of it.

* Here is a method that works: Open a random MP3 file that you don't care about and in the middle of it, create a few seconds of tone at 21kHz. You will see that appear right at the top of the spectral view, or very clearly in the Frequency Analysis box.  Now do a Save. You will notice that the 21kHz signal is still present on what it claims is your MP3 file. Now close it, go to the Recent Files list and reopen it. You'll find that the 21kHz tone is now missing. This is because it's way outside the Critical Band limits for an MP3 file, and couldn't be encoded or decoded. But it was still there on the visible file when you saved it as an MP3, wasn't it? That's because, despite what it says on the screen, it wasn't an MP3...