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Topic: When you convert an mp3 file to an AIFF file, do you get back all that (Read 14888 times) previous topic - next topic
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When you convert an mp3 file to an AIFF file, do you get back all that

Hi there,

I am new to mp3 research, and I have a lot of questions, but so far have not found a lot places to get reliable answers. I've tried lame.sourceforge.net, but I can't seem to find a forum or an e-mail address to send my questions to. I've even tried the Fraunhofer Institute, but again, no welcoming sense of being open to mp3 questions, in either a forum or an e-mail address.

Instead of flooding you with thousands of questions in this first post, I thought I'd start out simple, with one question at first, and then see how it goes.

QUESTION:
If you take a compressed mp3 file and convert it into an AIFF file, using a sound editor such as Sound Studio 4, do you get back all the lossy parts originally eliminated from the mp3 file, or do you just get a large AIFF file with all the parts that the original conversion to mp3 removed?

I know that the AIFF file is a much larger file, but does that mean you get back any of your lost parts from the "lossy" compression, or do you just have a large AIFF file that sounds identical (and just as bad) as your original mp3 source file?

Thanks for your help.

Jim Carruth

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #2 –
When you play an MP3, it is the same as converting it to WAV or AIFF and playing that. You do not get back what was lost.

MP3 is simply incapable of (quantitatively) lossless reproduction. Even if the bitrate is maxed out and even if no frequency components need to be discarded, the components that are kept are stored imprecisely, and the entire process also just results in slightly imprecise timing, such that transients (short, fast sounds) become smeared.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #3 –
Quote from: Apesbrain on
http://www.hydrogenaud.io/forums/index.php?showtopic=106474

...among many others.


Apesbrain,

So it just makes a larger file of the same info that's in the mp3 file, and doesn't restore anything that was lost. I kind of thought this was the case, like making a photocopy of a photocopy, instead of making a digital copy of the original, unadulterated file. Thank you for clearing that up for me.

Question 2:

Anyone know why mp3s made or converted within iTunes work better on iPods and mp3 CD players than mp3s made with the LAME encoder?

I use Sound Studio 4 to EQ my dull-sounding mp3 files, and I actually end up getting a much better sound out of them, once some of the lost highs and lows have been restored. But SS4 uses LAME to save the mp3 files, and the LAME-encoded mp3 files are now causing playback problems on my iPod and mp3 CD player, stuttering badly or cutting out altogether. Before I took them into SS4, this never happened, so I am assuming that LAME is to blame.

A Google search provided me this clue: iTunes does NOT use the LAME mp3 encoder as Sound Studio 4. So, how do I process my newly EQ'd files in an mp3 encoder that will not fail in iTunes, iPod, or an mp3 CD player? Is there there something out there that does the job better than LAME?

Thanks,

Jim Carruth

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #4 –
Quote from: jcarruth on
Anyone know why mp3s made or converted within iTunes work better on iPods and mp3 CD players than mp3s made with the LAME encoder?


Unless theres something wrong with your player, they should all work equally well. 

Quote from: jcarruth on
I use Sound Studio 4 to EQ my dull-sounding mp3 files, and I actually end up getting a much better sound out of them, once some of the lost highs and lows have been restored. But SS4 uses LAME to save the mp3 files, and the LAME-encoded mp3 files are now causing playback problems on my iPod and mp3 CD player, stuttering badly or cutting out altogether. Before I took them into SS4, this never happened, so I am assuming that LAME is to blame.


Something wrong with your player or the software you're using to encode the files.  Troubleshoot and see which it is. 

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #5 –
Quote from: jcarruth on
Anyone know why mp3s made or converted within iTunes work better on iPods and mp3 CD players than mp3s made with the LAME encoder?

I have been using Lame-encoded mp3s with i-devices for over 12 years without any issues.  Maybe SS4 is doing something wrong? 

BTW, you can assign an EQ profile within iTunes so that you don't have to mangle your mp3s by transcoding them.  You mentioned you're "restoring" your dull-sounding mp3s, presumably to some earlier state.  Can you elaborate on what this is?

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #6 –
Jim, you mentioned restoring "the lost highs and lows". I would challenge you on your assumptions about what has been lost, as well as what your "restoration" actually entails.

For the lows, expectation bias is partially at play; you know MP3 is discarding something, and you hear a difference in the bass, so you figure bass was lost. But knowing what we do about the format, it is doubtful there are any audible, discernible bass frequencies missing. This wouldn't be too difficult to verify objectively by analyzing the audio. I guarantee all the bass frequencies that matter are still there, even if you are using low bitrates. Also consider this: I had someone tell me, when I played the same file for them twice in a row (they thought I was playing different files), that one had deep, rich bass, and the other sounded weak and thin. Both plays sounded identical to me because I knew they were the same. In other words, some variability in what you hear is actually imagined.

High frequencies are another matter. As the bitrate goes down, there's not enough room to encode the audible portion of the relatively noisy/chaotic higher frequency bands, so the first stage of encoding is to simply strip out everything above a certain frequency so that everything below can be adequately represented. You didn't mention a bitrate or quality level, but since you're encoding for portable devices, I assume you're choosing space-saving settings. When encoding at less than 128 kbps, the lowpass filter may well be rolling off some of the upper midrange where there is actual audible musical content.

You can't restore anything above the lowpass filter's cutoff, as it's simply not in the MP3 to begin with. You can only re-EQ what remains, i.e. selectively adjust the volume of frequency bands, emphasizing some more than others. This is all you are doing in Sound Studio. You are not adding anything.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #7 –
Quote from: jcarruth on
I use Sound Studio 4 to EQ my dull-sounding mp3 files, and I actually end up getting a much better sound out of them, once some of the lost highs and lows have been restored.


Have you tried to blind test this with volume adjustment? (Lossless source to un-EQ'd mp3, of course.  Certainly you will find that the EQ changes the sound.)

A different issue is that processing an mp3 this way, will re-encode it. You get the "loss" in "lossy" twice (or more).

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #8 –
After encoding to MP3 a lot of information is simply lost, so there's no way to restore it. Any tool which claims to do that is lying to you. Of course it's still possible to alter the audio after encoding, but since the very aim and purpose of MP3 encoding already is to create an audibly equivalent compressed file, I don't see why you expect that any of these alterations will lead to improvements, as long as you trust LAME/MP3 enough to produce audibly transparent files. If not, use a different encoder/codec, or not use lossy compression at all.
It's only audiophile if it's inconvenient.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #9 –
Others have already told you that what you are doing to those MP3 files does not restore, but only changes them.
Sometimes its good to EQ some low quality files to make them sound slightly better, but others, it's really just opting between dull sound or more artifacts. It's up to you to decide if your process is worth your effort, but at least be aware that it's not going to work in all cases.

Now, onto the compatibility issues with LAME encoded files, it is strange, but it can happen.
I don't know that software, and I don't know the version of LAME that uses, or how they built LAME. (I see they refer to an external link in their webpage).

What I can suggest to you is to try using CBR instead of VBR. That might help, or might not.
There were some internal options to be more strict with the MP3 format (so that older, more simple mp3 decoders could work well), but those will not be available from within Sound Studio.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #10 –
Wasn't there a compatibility issue with the bit reservoir when using CBR320 with older versions of Lame?

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #13 –
To sort of summarize what others have said:

If you use a decent, modern codec (like LAME) at a reasonable bitrate, any perceived difference is likely imaginary.

If you take an MP3 file, process it in some way, and then write out the result to an MP3 file (what you say you have done to "improve" it), you have actually applied lossy compression onto a file that was already lossy compressed, thus degrading it further.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #14 –
Thanks guys for all your help. Not really looking for a discussion on EQing files.

I misspoke when I said that I restored some of the lost highs and lows. What I meant to say was I used EQ to greatly improve the sound of my mp3 files. That launched a whole bunch of challenging questions about what I was doing, how I was doing it, my assumptions, did I volume test it, did I know was changing the files, one guy actually used the word "mangling" the files. Jeepers! What a mad bunch of guys you all are!

Sure, I know it changes them. So what? I keep a copy of the original file.

A discussion of EQing mp3 files was not what I had in mind. What I was wondering was why the newly-edited files were failing during playback, when the original mp3 files played fine. No one here seems to know the answer to this.

Maybe when you change an mp3 file and save it, the saving, or compressing an already compressed file corrupts it in some way. I think I'll try converting the files to aiffs, make my EQ edits, and then save it to mp3 format. At least that way I won't be compressing on top of an already compressed file. That make sense to anyone? 

Instead, I got a lot of group hostility about EQing mp3 files. Wasn't looking to go there, but it seems like everyone but JAZ had an ax to grind with (heaven forbid) the idea that I might want to EQ an mp3 file to try and make it sound better. By the way, you can make an mp3 file sound a whole lot better if you just take the time to practice with your 10-Band EQ filter, and drop your unfair and uncalled for prejudices against it. And no, it's not my imagination. Where the EFF is all this hostility against EQing an mp3 file coming from? It's like I insulted your mother or something. Jeez guys, that the way you treat the new guy?

I didn't ask about EQing my files. I asked why my newly-edited files were failing during playback. Do you think you can actually answer the question, or do you want to just berate me about my EQing practices. If so, I have no interest in this. In fact, it sounds pretty hostile to me.

Maybe this is not the right forum for me. Being greeting with such hostility on my first visit is a real turn-off. Maybe you ought to look at how you treat your visitors. I didn't expect any of that on my first visit.
Sure doesn't encourage me to want to come back.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #15 –
Quote from: jcarruth on
By the way, I said absolutely nothing about restoring files.

Ah, but you did say something about restoring lost highs and lows:
Quote from: jcarruth on
I use Sound Studio 4 to EQ my dull-sounding mp3 files, and I actually  end up getting a much better sound out of them, once some of the lost  highs and lows have been restored.

Quote from: greynol on
You mentioned you're "restoring" your dull-sounding mp3s, presumably to some earlier state.  Can you elaborate on what this is?

I used scary quotes around the word restoring because I didn't understand what it you meant and was seeking some clarification.  The fact is that some people erroneously think that mp3 compression will alter the tonal balance of a track.  To be honest, I suspected you may have thought this but decided to ask rather than accuse.  I was a bit disappointed to see others just proceed assuming this was the case.

Quote from: jcarruth on
I said I could greatly improve the sound of my mp3 files by EQing them, and I have done this, believe it or not.

Realizing that this is a subjective thing, I believe you.

Quote from: jcarruth on
You want me to explain myself, defend myself, so you can then tell me how wrong I am. Boy, you can just feel the hostility rising in waves off the page. That the way you welcome the new guy? That sucks.

What, like this recent post of yours?  Look, I'm sorry you took our replies the wrong way, but maybe you should reconsider where people are coming from.  We've seen all sorts of misconceptions about audio quality on this forum, including the notion that EQ-ing can some how restore the wretched things that lossy encoders do to music.

Quote from: jcarruth on
And who says I'm mangling them? That just sounds hostile, and tipped me off to what kind of forum this is.

You've completely misunderstood.  Please read my sentence again(!):
Quote from: greynol on
BTW, you can assign an EQ profile within iTunes so that you don't have to mangle your mp3s by transcoding them.

I couldn't care less about your EQing your music.  It was about the generational loss by going from mp3 to mp3 that I tried to warn you.  Unlike more modern codecs, temporal smearing can be exacerbated when transcoding mp3s, to the point where artifacts otherwise masked may become audible, even when using the highest possible quality settings.

Whenever possible, it is preferable to make changes to the original lossless source and then encode to mp3.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #16 –
greynol,

You're quoting a post I edited. There were a lot of inaccuracies in it, so I corrected those. Now your post doesn't make sense.

Quote
I couldn't care less about your EQing your music. It was about the generational loss by going from mp3 to mp3 that I tried to warn you. Unlike more modern codecs, temporal smearing can be exacerbated when transcoding mp3s, to the point where artifacts otherwise masked may become audible, even when using the highest possible quality settings.

Whenever possible, it is preferable to make changes to the original lossless source and then encode to mp3.


And where did I ask a question about EQing files? I don't remember asking about that. You are answering a question that I didn't ask.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #17 –
Quote from: greynol on
We've seen all sorts of misconceptions about audio quality on this forum, including the notion that EQ-ing can some how restore the wretched things that lossy encoders do to music.

Like this doozy:
https://www.hydrogenaud.io/forums/index.php...mp;#entry787986

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #19 –
greynol,

Can you just delete all my posts and unregister me from this forum? You guys are just too hostile for my taste. There's too much of a disconnect here that I am feeling.

Thanks.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #20 –
Quote from: jcarruth on
Quote
I couldn't care less about your EQing your music. It was about the generational loss by going from mp3 to mp3 that I tried to warn you. Unlike more modern codecs, temporal smearing can be exacerbated when transcoding mp3s, to the point where artifacts otherwise masked may become audible, even when using the highest possible quality settings.

Whenever possible, it is preferable to make changes to the original lossless source and then encode to mp3.

And where did I ask a question about EQing files? I don't remember asking about that. You are answering a question that I didn't ask.

You might want to read that above quote of mine one more time.

My use of the word, "mangling," which has apparently caused you such consternation is about making an mp3 from an mp3.  It was not about the edits you made prior to making that second generation mp3.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #21 –
Quote from: jcarruth on
I think I'll try converting the files to aiffs, make my EQ edits, and then save it to mp3 format.

Which files are you converting to aiff?

Quote from: jcarruth on
At least that way I won't be compressing on top of an already compressed file. That make sense to anyone?

Are you importing mp3s into your editor directly?  If so, the editor is already decoding them to PCM (aiff).

My second question may be redundant, but I thought I'd ask it anyway since your explanation of what you're trying to do is a bit vague.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #22 –
Quote from: jcarruth on
Can you just delete all my posts and unregister me from this forum?

From our Terms of Service:
Quote from: CiTay on
-> 12.

[...] Accounts are never deleted. [...]

The same is true for posts.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #23 –
Ok, let’s start over. The only way I know how to edit an mp3 file is to open it in my sound editing program, which is called Sound Studio 4. You then said that once you open it in your editor, it decodes it into an aiff file.

Quote
Are you importing mp3s into your editor directly? If so, the editor is already decoding them to PCM (aiff).


So, once I’ve made my edits to the file now open in my editor, when I go to save it, I’m reconverting the aiff file back into an mp3 file, NOT saving an mp3 file on top of an mp3. And you are calling this a second generation mp3.

Is this understanding correct, so far?

Quote
My use of the word, "mangling," which has apparently caused you such consternation is about making an mp3 from an mp3. It was not about the edits you made prior to making that second generation mp3.


In the above quote, you refer to making an mp3 from an mp3. I’m not sure how you would do this, if opening the file in the editor decodes it back into an aiff file. Not that I would want to do it, but how do you make an mp3 from an mp3 unless you open it in an editor first? (just so I know how to avoid doing this).

Thanks.

When you convert an mp3 file to an AIFF file, do you get back all that

Reply #24 –
Quote from: jcarruth on
So, once I've made my edits to the file now open in my editor, when I go to save it, I'm reconverting the aiff file back into an mp3 file, NOT saving an mp3 file on top of an mp3. And you are calling this a second generation mp3.

Is this understanding correct, so far?

This is correct, though the mp3 is decoded to PCM when taken into your sound editor.  Aiff is merely the container format Apple uses for PCM data; and an aiff file is likely only created if you explicitly tell your sound editor to save the PCM data as such.  This has no bearing on the matter at hand, however.

Quote from: jcarruth on
how do you make an mp3 from an mp3 unless you open it in an editor first? (just so I know how to avoid doing this).

There are ways of making edits to an mp3 without decoding to PCM and re-encoding that PCM back to mp3, but I don't know if there are any tools out there to do what you want to do, nor do I know if they will do them to your satisfaction, as they are basically limited to adjusting the gain of each scalefactor band in somewhat coarse adjustments and the bands might not necessarily fall in the frequency regions you want them to.  You still risk making artifacts audible (or more audible) as well, though I don't think you'll get additional temporal smearing to the extent that you would by re-encoding.  The graphic EQ used in old versions of Winamp is the only example that, IIRC, employed this method of manipulation that I can come up with.

You don't need a sound editor to decode and encode mp3s, BTW.  Just use the codecs or some front-end like XLD if you prefer.