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This article is the response to the comments and the mails I receive about testing new audio codecs and deciding which one is the best to store your music. I am not going to spend again several months researching everything I can about audio and trying with my own ears and my friends ears too nor I am going to get more CD’s with all kinds of musics to have diversification.

Now with my experience I need to tell you just one thing: Mp4 is getting a terrible quality because of the way it is being made. NERO 6 (yes the old version six from 2004) has actually the best Mp4 encoder I have ever seen. It has the best quality with the lowest bit rate. However this is not the best encoder to use today because after that time a lot of research and improvement has been made on the Mp4 codec but the new Nero while using them, killed many top quality features such as variable bit rate, downmix to mono because most musics do not make full use of stereo so you can double the quality of the sound with the same bit rate and finally you cannot have high efficiency encoding at high bitrates which makes good mp4 audio almost as big as lossless audio.

Mp4 is nothing but an AAC file with a different extension. Mp4 is a container which can contain for example OGG or WMA or AAC or even Mp3 and play many extensions at the same time like AVI and AAC and make a video. This is not the best way to explain it but it’s the best I can come up with now. This is why you won’t find many Mp4 encoders on the internet, even NERO can make you choose between Mp4 and the ORIGINAL file which is AAC. Encoding your music to AAC is the very same thing as encoding it to Mp4, just changes the extension.

This is from the Hydrogen Audio Forums

” Great, so you’ve given me all the technical stuff, but what is AAC really?

AAC is the culmination of the current state of the art audio encoding techniques. It is designed to improve upon and replace MP3 as the defacto Audio Encoding standard. It usually offers (depending on the codec) equivalent quality to MP3 at a lower bitrate.
What is the difference between *.MP4 and *.M4A?

Besides the extension, absolutely nothing. Apple came up with extension to distinguish between files with Video and Audio (the MP4 extension) and files with Audio only (the M4A extension). As far as the internal structure of the file, nothing is different.”

So just the extension is changed to fit hardware.

The new WMA 10 is not much better than it was before and the Microsoft Media Encoder does not run on Vista and on Xp is is slow and buggy. Microsoft made a listening test comparing WMA with AAC and the test is just unfair, audio is much more than just a few tracks and very specific codec features. A desperate try to keep people off the right track. Microsoft uses Mp3 files in all it’s systems (Windows, Games, Other Sounds) so they are just like the smokers that say smoking is bad…

So what’s the final? If you want ultimate quality just stick with the lossless Audio but stay away from WMA, once it becomes WMA it’s WMA forever so avoid it. FLAC is a good codec, Monkey audio too… in Lossless audio only size and encoding and decoding speed changes.

Looking for portable music or internet streams? AAC V2 VBR Downmix to Mono. You should have a 32 KB’s file with the same (the very same, I am serious here) quality as an 128 Mp3 file.

Where is the magic? Mp4 64 KB’s CBR is as good as Mp3 128, then the downmix makes 32 KB/s as good as stereo 64. So simple.

For extreme size, the VRB can go as low as 24 KB/s.

Another final thing, when Microsoft says 64 WMA is as good as CD quality they are lying to you.