m4a file format - what is this?, page 1

For the beginning:
I have seen this great thought said by kinaD:
"Tribalmixes is going down…
and further
… uploading in FUCKING useless m4a format"

Anyway …
Here is some information for those who do not know how to make an .m4a file usefull.
• First way, download and install plug-in for the player you use. There should be plug-ins for every player.
• Second way, decode the .m4a file to a .wav file and then use this file for everything you want including as a source file for any compression you want with a quality up to the quality of the .m4a file.

I usually announce a worse quality than the real quality, so the decoded file quality could be better.
As an example I have checked out my last upload:  DJ Ralf at Saw Radio on XM80 26-May-2007.m4a
It is announced as 224 kbps and actually is VBR avg 216 kbps generated by NeroAACenc with a quality factor of 0.60. For an idea, the encoder generated a VBR file @avg 377 kbps with the maximum quality factor of 1.0 for the same source.
After having decoded .m4a to a .wav and then having encoded it to an mp3 @ 256 kbps I have inspected the spectra and couldn’t find any essential differences. So, it is actually a 256 kbps or higher quality.
The .m4a file size is 85.07% of the corresponding .mp3 file size.

P.S. My first attempt to recover a .wav file form .m4a has resulted in a 128 kbps file although the input file had much higher quality. I do not know why this has happened. My last attempts to recover a .wav  from an .m4a have results as expected, which means the quality is as the input file quality.

what a stupid comentsource https://www.m4a.com/

I don't download m4a files either,just too much messing around
mp3 is just fine for me.why should i be expected to download & install stuff just to please someone who cant be bothered to convert to a format which is popular.
If it don't play in winamp or media player,then it sux  

i can tell one thing here... i usually get mp3s, but don't really care, since i burn them, so format doesn't matter.. anyways, i usually say i'll listen to it in my car and comment.. well, on my home speakers 2-5w and 20w woofer, or something like that, i could really clearly hear jonathan peters' show in very good quality, just simply without any technical stuff, m4a quality is WAY better than mp3, you can probably hear the big difference in earpieces as well.

you dont really need to install anything most players already come with the ability to playback m4a..so stop nagging and crying...and start enjoying better quality audio

So My mp3 tools will work with m4a files?
I don't think they will.Normally I like to set the tags on files I download,using mp3 Tag & Rename,
also a m4a tag doesn't show up in winamp,so i cannot import any info into my tag scanner.
Sorry but m4a is not as good as you make it out to be.I speak not of quality,just its versatility.
I will stick to mp3,simple,effective,& easy to work with.

so what were u did when was no mp3? m4a is basically mp4 with only audio content (without video or other media) which means its the way to go, the future, progress...etc. and sure it will be develop in contrast to mp3 which is already spent

Maybe you're right about it being the future format,but as we are in the present,&
Bill Gates hasn't included m4a recognition in the latest Windows Vista OS,
Then I am still not convinced,& will stick with mp3.
I still don't see m4a players in the high street shops,(plenty of mp3 players there tho)
I don't mind change,as long as I can get the tools I need in which to work with the files.
I will still stick with the majority.

sure, there are ppl who are minority and show the direction and ppl who are majority to follow it when they got convinced

congratulations...

I would continue showing m4a encoder advantages:
• I tried to recode 01_armin_van_buuren_-_a_state_of_trance_302_05-31-2007.mp3 preserving its 192 kbps quality (preserving almost the same signal spectrum). The result I have is an m4a @ 172 kbps with the (almost) same spectrum.
• When I encoded John Digweed at Transitions on XM80 31May-2007.m4a I had to go to a little bit higher bit rate. Then, it turned out the VBR avg 260 kbps m4a preserved the recorded signal spectrum better than an mp3@320 kbps.

Note: I use “almost” because I cannot avoid it. Without it I have to proof strictly the spectra are the same. But for a listener the music should be the same because the spectra, and accordingly the sound signals are very close.

Here I would like to provide some information about the possibilities of Lame v 3.97 – an mp3 encoder and NeroACCenc 2007-02-13 - Version 1.0.7.0 – an m4a encoder, related to the sound quality.

To compare them I use the following:
"The three parameters of digital audio quality are: signal bandwidth, fidelity and spatial realism".
The spatial realism is provided by increasing the number of spatial channels. The common formats are:
1-channel (mono), 2-channel (stereo), 5-channel, 5.1 channel, 8-channel.
The fidelity refers to the level of perceptibility of quantization or reconstruction noise. It is evaluated by formal listening tests.

It is clear; I am going to talk about signal bandwidth as a measure of sound quality.
The compact disk (CD) is today's de facto standard of digital audio representation. On a CD with 44.1 kHz sampling rate the resulting stereo bit rate is 1,411.2 kbps and the max possible signal bandwidth is 22.05 kHz.
The presumption is:
We have an audio CD file with a full signal bandwidth of 22.05 kHz. Then we encode it and check out what has happened to the signal bandwidth of the encoded file. If the signal bandwidth has been reduced the sound quality has been reduced also. The bigger the reduction of the signal bandwidth the worse is the sound quality.

Here are spectra to compare:
* a 00:00:58.757 sec piece of the track (08) Basic Perspective - Small Step To The Other Side (Elevation Remix) (AVB ASOT CD1) named as asot.wav,
* two mp3s at the max possible quality (which include a bit rate of 320 kbps): asot.mp3 generated with a (encoder) filter parameter -k and kasot.mp3 without using it,
* an m4a at 320 kbps





You can hardly find differences between both files: wav and m4a. But the differences between wav and mp3s are more than obvious. To see them better here are the high frequency ranges.





It is clear: m4a @320 preserves the signal entirely while mp3@320 cannot.

Here are two more spectra to compare mp3 and m4a encoders: of an mp4 @192 kbps and an mp3 @320 kbps. The differences below the red line are less than the quantization noise of the CD.



It turned out an mp4 @192 kbps is better than an mp3 @320 kbps. So, what is an m4a?

Here you can see an m4a @200 kbps spectrum very close to the original wav spectrum. And , of course, every bit rate higher provides better quality.

m4a is just another extra step. I understand the quality improvement, but that is really not worth the extra step of converting it back to mp3 or wav every time I want to burn a cd into cd audio format. Some of us don't have the high end tools and players you guys do. I'm just a dude wit a regular system taking regular audio cds.

Exactly My Point,Well said,this is what I am talking about,All the tech stuff don,t mean nothing
to the majority of downloaders on here.But regardless of what the users want,we still get inundated with
Stupid file formats that have us running all over the internet,doing googles,and masses of hours spent,
trying to decypher all the tech crap,just to end up with a cd.

Mp3 Rules & will always RULE as long as all the other files & formats are not included as part & parcel Of an operating system,or a player is available in the shops!!!

                                                            WE WANT MP3

WHAT PART OF THAT DO THE UPLOADERS NOT UNDERSTAND??????????????????????????????????????

Well, :)
“On a CD with its 44.1 kHz sampling rate the resulting stereo net bit rate is 2 x 44.1 x 16 x 1000 = 1.41 Mb/s. However, the CD needs a significant overhead for a runlength-limited code, which maps 8 information bits into 14 bits, for synchronization and error correction, resulting in 49-bit representation of each 16-bit audio sample. Hence, the total stereo bit rate is 1.41 x 49/16 = 4.32 Mb/s” (Peter Noll – Technical University of Berlin in The Digital Signal Processing Hand Book).
The CD format is in essence a PCM (Pulse Coded Modulation) with added error correction code. A PCM signal is the content of a wav file. So, when burning a CD from an mp3 file you do the same as burning it from every audio file format:
• First, the input data, if not in PCM format, are converted to PCM format,
• Then, these data are recorded to the CD.
One more thing to mention, if you burn an mp3 @192 kbps, the best quality you can buy over the Internet, you need 4.32/0.19 = 22.74 times more information storage to hold this file.
Obviously, you do not archive such files this way.

Sorry but I have never seen a worse case of copying & pasting in my entire life.
That was as uninteresting as watching paint dry.
Anyway this is my final comment on this issue.
You won't understand it tho (I think it is too technical for you)

WE WANT MP3!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!