AdrianNewington
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MP3 & M4a question
Hi,
I discovered I was accidentally creating low bit rate MP3's for my basic listening evaluations on my iPhone, so I went back into Adobe Audition and found I had a crappy bitrate so I modified it to 320kbps. I also decided to investigate if lossless formats like flac could be imported in iTunes.
I found that iTunes would not support flac, but most recommendations said just convert it to "M4a" to simplify things.
I thought OK... I'll use Audacity to convert my WAV's, but then I did a comparison of file size from my 320 kbps Adobe Audition MP3's, and thats were I got a bit confused about standards of quality.
This is what I found after converting my WAV Mixdown, but I don't know if this is relevant to the quest of best quality.
My WAV file = 46.7Mb
The 320 MP3 = 10.6Mb
The M4a = 6.5Mb
What does the files size say about the quality of the format. Does M4a always beat MP3 in quality?
Thanks
Adrian
Music to Uplift & Inspire. Windows 10 64 bit - HP 23" All-In-One PC Sonar Professional, ( and X1 Producer, X3 Basic).
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Sycraft
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Re: MP3 & M4a question
2016/11/11 02:20:43
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Likely, you won't be able to hear any difference at all. For one, 320k MP3 is higher than tend to be useful. Generally 256k MP3 is pretty well regarded as transparent (meaning nobody can tell subjectively the difference from uncompressed, even on really good equipment) and for a lot of consumer uses (like earbuds on a portable) 192k sounds as good as the original.
Well M4a can and should contain AAC audio (I say can because it is a container format, not a compression format in and of itself) which is generally more efficient than MP3. It is newer, based on better research of acoustics and human perception and so can get more transparent sound to our ears with less bits.
So I'd expect that for your use, you won't notice any difference, the more efficient AAC encoded M4a files will sound just like the WAV files.
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bitflipper
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Re: MP3 & M4a question
2016/11/11 09:07:26
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☄ Helpfulby sven450 2016/11/11 09:38:41
Although there is a direct relationship between file size and quality within a given format, it does not necessarily apply across unlike formats.
For example, a FLAC file is going to be twice the size of a 320 kb/s MP3, but you will not hear any difference between them. Technically, the FLAC file is true to the original source and the MP3 is not, but a 320 kb/s MP3 is past the threshold below which which humans can perceive any flaws.
M4A is generally thought to be higher-quality than MP3, but you've got to really split hairs to make a case that anybody can hear the difference. So why doesn't everybody switch to M4A and get smaller files of higher quality? Because outside the bubble of Apple World it's not been widely adopted. MP3 assures the widest compatibility.
Some trivia: M4A is actually AAC in disguise. AAC is how music gets from distributors to your radio station. When you listen to FM radio, you're listening to 256 kb/s AAC-encoded files. AAC retains fidelity better at lower bitrates. 192 kb/s AAC is indistinguishable from 320 kb/s MP3, so 256 kb/s AAC is overkill.
 All else is in doubt, so this is the truth I cling to. My Stuff
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bitflipper
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Re: MP3 & M4a question
2016/11/11 09:49:57
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BTW, you can get a free, fast command line AAC encoder here. It'll do up to 381 kb/s, CBR or VBR. I've done a little experimenting with it, but never adopted it because my portable player doesn't support AAC so it ultimately was of no use to me. I'd use "-q 0.75" for a bitrate of 285 kb/s. That produced smaller files than a 320 kb/s MP3 but sounded exactly the same. Soundcloud, however, does support AAC, so if that's your primary window to the world for sharing your music then AAC is a viable alternative to MP3.
All else is in doubt, so this is the truth I cling to. My Stuff
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AdrianNewington
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Re: MP3 & M4a question
2016/11/11 23:05:20
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Thanks Biitflipper.
That's really interesting info. Cheers!
Music to Uplift & Inspire. Windows 10 64 bit - HP 23" All-In-One PC Sonar Professional, ( and X1 Producer, X3 Basic).
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drewfx1
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Re: MP3 & M4a question
2016/11/12 12:41:37
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☄ Helpfulby twaddle 2016/11/16 07:38:45
bitflipper
Although there is a direct relationship between file size and quality within a given format, it does not necessarily apply across unlike formats.
I like to emphasize the point here that once something is transparent, you can't improve it. For some reason when it comes to audio lots of otherwise intelligent folks passionately convince themselves of stuff like, "even if I can't hear a difference, if I could hear a difference this would be better, therefore it's better".
 In order, then, to discover the limit of deepest tones, it is necessary not only to produce very violent agitations in the air but to give these the form of simple pendular vibrations. - Hermann von Helmholtz, predicting the role of the electric bassist in 1877.
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Soundwise
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Re: MP3 & M4a question
2016/11/13 03:13:51
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drewfx1
bitflipper
Although there is a direct relationship between file size and quality within a given format, it does not necessarily apply across unlike formats.
I like to emphasize the point here that once something is transparent, you can't improve it. For some reason when it comes to audio lots of otherwise intelligent folks passionately convince themselves of stuff like, "even if I can't hear a difference, if I could hear a difference this would be better, therefore it's better".
The truth is, even though people cannot safely tell one codec from another just by listening, there are things people can feel. I mean, in the long run, higher quality audio feels a lot better, even though it may seem undistinguishable from a lower quality audio in a AB test.
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bitflipper
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Re: MP3 & M4a question
2016/11/13 09:03:45
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But in that case, where the listener is able to detect some very subtle difference, even when too subtle to put your finger on what that difference is, then the encoding is not "transparent". Drew's point still stands.
All else is in doubt, so this is the truth I cling to. My Stuff
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Soundwise
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Re: MP3 & M4a question
2016/11/13 09:42:54
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bitflipper
But in that case, where the listener is able to detect some very subtle difference, even when too subtle to put your finger on what that difference is, then the encoding is not "transparent". Drew's point still stands.
And vice-versa: if it's not transparent, at least technically, then the listener may be able to detect it under certain conditions. But then again, no matter how transparent, true to the source or perfectly balanced the mix is, it's the music that we listen to, not just a bunch phase-aligned amplitudes and a conflict-free frequency spectrum. So many great tunes were recorded with gear that was far from being perfect.
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drewfx1
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Re: MP3 & M4a question
2016/11/13 13:27:24
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SoundwiseAnd vice-versa: if it's not transparent, at least technically, then the listener may be able to detect it under certain conditions.
If one can detect it then they can detect it. If not then they can't. In audio contexts "transparent" means the listener can't detect it - IOW, it refers to the listener's perspective, not the technical properties of the audio.
In order, then, to discover the limit of deepest tones, it is necessary not only to produce very violent agitations in the air but to give these the form of simple pendular vibrations. - Hermann von Helmholtz, predicting the role of the electric bassist in 1877.
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Soundwise
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Re: MP3 & M4a question
2016/11/13 14:23:34
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drewfx1
If one can detect it then they can detect it. If not then they can't. In audio contexts "transparent" means the listener can't detect it - IOW, it refers to the listener's perspective, not the technical properties of the audio.
Hmmm. Sounds like "if black is black then it's black. If it's not then it's not." Well, English is not my native language and I have a hard time interpreting "transparent" as "indistinguishable". I mean, the window glass is usually as transparent as it can be, but you still can tell you are looking through the glass if you pay attention to light reflections and retractions. In other words, "transparent" in this context does not mean "impossible to detect", but rather "almost impossible to...", or "very hard to...". Peace! 
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drewfx1
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Re: MP3 & M4a question
2016/11/13 16:51:41
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In audio discussions, especially in regard to lossy compression, it means "impossible to detect any difference": https://en.wikipedia.org/wiki/Transparency_(data_compression)
In data compression and psychoacoustics, transparency is the result of lossy data compression accurate enough that the compressed result is perceptually indistinguishable from the uncompressed input.
In order, then, to discover the limit of deepest tones, it is necessary not only to produce very violent agitations in the air but to give these the form of simple pendular vibrations. - Hermann von Helmholtz, predicting the role of the electric bassist in 1877.
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Soundwise
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Re: MP3 & M4a question
2016/11/13 17:12:49
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Drew, exactly! The key words here - lossy, accurate enough, perceptually indistinguishable. Yet not impossible.  That's what I'm talking about.
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drewfx1
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Re: MP3 & M4a question
2016/11/13 18:18:05
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Um, no. Perceptually indistinguishable means indistinguishable. If it's distinguishable then it's not transparent by definition. You are confusing a hypothetical with reality, i.e. making the exact mistake I mentioned earlier:
For some reason when it comes to audio lots of otherwise intelligent folks passionately convince themselves of stuff like, "even if I can't hear a difference, if I could hear a difference this would be better, therefore it's better".
In order, then, to discover the limit of deepest tones, it is necessary not only to produce very violent agitations in the air but to give these the form of simple pendular vibrations. - Hermann von Helmholtz, predicting the role of the electric bassist in 1877.
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Sycraft
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Re: MP3 & M4a question
2016/11/13 23:31:43
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drewfx1
Um, no. Perceptually indistinguishable means indistinguishable. If it's distinguishable then it's not transparent by definition. You are confusing a hypothetical with reality, i.e. making the exact mistake I mentioned earlier:
And to add to that, when we are talking lossy compression, perceptual difference is the ONLY difference we care about. We know that there is a measurable difference, that's why it is lossy (it would be lossless if there was no measurable difference) it doesn't matter what that is or how much, we are interested if humans can hear a difference and if so, how much. For audio, transparency isn't that hard to achieve these days. A lot of the modern formats can achieve it at a fairly low bitrate.
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jmasno5
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Re: MP3 & M4a question
2016/11/14 00:18:17
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bitflipper
BTW, you can get a free, fast command line AAC encoder here. It'll do up to 381 kb/s, CBR or VBR.
Soundcloud, however, does support AAC, so if that's your primary window to the world for sharing your music then AAC is a viable alternative to MP3.
Doesn't SoundCloud crush everything to mp3 128 regardless of the format you upload?
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Soundwise
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Re: MP3 & M4a question
2016/11/14 08:23:57
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drewfx1
Um, no. Perceptually indistinguishable means indistinguishable. If it's distinguishable then it's not transparent by definition. You are confusing a hypothetical with reality, i.e. making the exact mistake I mentioned earlier:
For some reason when it comes to audio lots of otherwise intelligent folks passionately convince themselves of stuff like, "even if I can't hear a difference, if I could hear a difference this would be better, therefore it's better".
1. Higher fidelity doesn't always mean better. That's why we mask level fluctuations with compression and "raw edges" with reverb. Sometimes better means small file size, at other times better is used for wider compatibility, etc. 2. Perceptional ability is not a fixed constant. " Perceptually indistinguishable means indistinguishable" only under certain conditions, the most obvious being a) the age of the listener: b) room treatment: c) listener's gear:  Here is a measurement test: http://www.computeraudiophile.com/blogs/mitchco/16-44-vs-24-192-experiment-163/ My point is: if there is a measurable difference, small enough, that you can't claim to hear it or distinguish it in a blind test, you may still be able to feel in the long run, or in different circumstances. For example, we cannot see, feel, smell, hear or sense in any other way ultraviolet or X-rays. But when a person is exposed to such rays for a long while he/she will definitely start feeling it. It may or may not matter. It is usually safe to ignore all these perceptual subtleties. Yet here is a real life example, showcasing the use of frequencies beyond human perception: http://wzlx.cbslocal.com/2013/11/06/paul-mccartney-on-the-beatles-dog-whistle-on-a-day-in-the-life-watch-your-dog/
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bitflipper
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Re: MP3 & M4a question
2016/11/14 11:13:04
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☄ Helpfulby Soundwise 2016/11/14 12:41:56
Discussions of transparency, audibility and what's "good enough" always fall apart because the gray area between clearly-audible and clearly-inaudible is vast. Within that area are elements that can only be heard under certain circumstances, only with high-quality speakers, only by those with better-than-average hearing, only when listening intently, or only heard by trained ears.
Because we can't always be sure that no one else can hear what we can't hear, our strategy is to maintain the highest accuracy possible, to carefully attend to details that "probably" no one will notice, to aim for a higher quality than we think we need. It's why we mix with 32-bit data, even though what happens down in those lowest bits is almost never audible. It's why we intently listen to and correct the tiniest details that probably don't matter to the big picture.
Because we reflexively aim for the highest possible quality without asking ourselves how important it really is, many of those efforts are unnecessary. But I liken it to consistently using your turn signals when driving...if you do it by sheer habit, even when yours is the only car on the road, that reflex may someday save your life.
OTOH, a common trap for audio people is to get stuck in trivia while remaining oblivious to bigger mistakes. it's like a drunk driver making sure his oil is clean. Or obsessing over what dither algorithm to use while obliterating dynamics through over-compression.
All else is in doubt, so this is the truth I cling to. My Stuff
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drewfx1
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Re: MP3 & M4a question
2016/11/14 12:49:28
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SoundwiseMy point is: if there is a measurable difference, small enough, that you can't claim to hear it or distinguish it in a blind test, you may still be able to feel in the long run, or in different circumstances.
You claim "you may" but either you have to demonstrate that you (or someone) can or there's no reason to take your claim seriously. Claiming that you can imagine that something "may" be possible does not make it relevant in the real world. The burden is on you to demonstrate that you can "feel in the long run" a difference. Otherwise, it's just a supposition with no real world evidence to support it. Oh and by the way, I can make lots of suppositions with no evidence to support them and then demand that others disprove them.
In order, then, to discover the limit of deepest tones, it is necessary not only to produce very violent agitations in the air but to give these the form of simple pendular vibrations. - Hermann von Helmholtz, predicting the role of the electric bassist in 1877.
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John
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Re: MP3 & M4a question
2016/11/15 13:11:01
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I have a great deal of trouble with anything that talks about feeling. One can "feel it" is a very useless way of thinking about most anything. "I feel" is used so often when what is really meant by that is "I think". When we are talking about music I can agree we can feel bass if loud enough. Other then that what one feels is emotional poppycock! It should never be interjected into a rational discussion.
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