AAC@400kbps vs. MP3@320kbps?

[LfmC]

I know, I know.... wave. aif. flac. wavpack. etc.
But this is a specific case, as my new digital DJ setup only reads wav,aif,mp3,aac, and I really can't afford using uncompressed wave files. Not enough capacity.
On the other hand, I can easily give around 20MB of disk space per 6min track, meaning that both mp3@320 and AAC@400 are an option. I've heard and read a lot on the subject of AAC sounding better at low bit-rates, but never saw a comparison of max quality for both formats.
So my question is: Which do I choose as my format for this mobile DJ setup?

[LfmC]

Originally Posted by OKDK

Its so weird that you use a digital DJ setup for mastering. Where did you get that idea?

What mastering? I'm talking about a DJ setup. I've asked on the mastering forum as it seemed to be the best place to talk about audio file format quality.

[Greg Reierson]

To quote Jim Johnston, one of the inventors of MP3, on the subject of processing encoded audio: "DON'T DO IT!"

GR

[LfmC]

Okay, maybe I wasn't clear... I'm planning to copy my collection of flac to an external drive and convert to mp3/aac for playing in clubs, leaving my home collection intact. I'd go with wave, but the disk space won't allow it. So my question, again, is: Which of the mentioned formats gives better quality at maximum bitrate?

[wado1942]

Why not use FLAC? It's not as compact (around 700-800kbps), but is certainly a lot better quality. You could get a larger drive, or prioritize so only the material you need is with you.
That said, AAC at 400Kbps is superior to MP3 at 320.

[LfmC]

Originally Posted by wado1942

Why not use FLAC? It's not as compact (around 700-800kbps), but is certainly a lot better quality. You could get a larger drive, or prioritize so only the material you need is with you.

Like I mentioned in the OP, flac is not supported. And wave files are not an option ATM.

That said, AAC at 400Kbps is superior to MP3 at 320

Thank you. That's all I wanted to know.

[Joelistics]

Originally Posted by LfmC

Thank you. That's all I wanted to know.

Fair enough question. To my ears it depends on the codec. With LAME, mp3 320 sounds a tad better. With anything else I've tried highest quality aac sounded quite a bit better...

[SweetLossy]

Originally Posted by LfmC

So my question is: Which do I choose as my format for this mobile DJ setup?

In general AAC is better. It has better transient definition and this is good for reproducing music at high SPL.

Remember that some DJ softwares have problems with VBR and the song BPM lecture. Test your DJ setup or use CBR.

Originally Posted by Greg Reierson

To quote Jim Johnston, one of the inventors of MP3, on the subject of processing encoded audio: "DON'T DO IT!"

I do it all the time and clients are very happy.
Of course only at high bitrates from 192 kbps.
Transcoding or processing lossy encoded files is not bad, only depend of the original quality.

It entirely depends on the encoder.
At 320kbps MP3 vs 442kbps AAC, I've found nero's free ACC encoder to be superior to Lame.
Those two are as far as I know the best-in-class encoders, presently.

[LfmC]

Originally Posted by SweetLossy

In general AAC is better. It has better transient definition and this is good for reproducing music at high SPL.

Remember that some DJ softwares have problems with VBR and the song BPM lecture. Test your DJ setup or use CBR.



I do it all the time and clients are very happy.
Of course only at high bitrates from 192 kbps.
Transcoding or processing lossy encoded files is not bad, only depend of the original quality.

I'm converting my flac collection, so the source is lossless. I always use CBR for the same reason.

Originally Posted by soulstudios

It entirely depends on the encoder.
At 320kbps MP3 vs 442kbps AAC, I've found nero's free ACC encoder to be superior to Lame.
Those two are as far as I know the best-in-class encoders, presently.

Excellent, as I actually only have Nero AAC, so glad to hear it's also the best choice for AAC conversion.

Thank you all for the help.

[kosmokrator]

from one of the head-developers of LAME:

MP3'Tech - www.mp3-tech.org

*What is MPEG-2 AAC ?

MPEG Advanced Audio Coding (AAC), also known as MPEG-2 NBC (Non-Backward Compatible) represents the actual state of the art in natural audio coding.

It is able to handle a lot more channels than MP2 or MP3 (48 full audio channels and 16 low frequency enhancement ones compared to 5 full audio channels and 1 low frequency enhancement one for MP2 or MP3), and it can handle higher sampling frequencies than MP3 (up to 96kHz compared to 48kHz). MPEG formal listening tests have demonstrate that for 2 channels it is able to provide slightly better audio quality at 96 kb/s than layer-3 at 128 kb/s or layer-2 at 192 kb/s.
*How does MPEG-2 AAC work ?

AAC uses the coding tools already present in MP3, but uses them in a better way:

* The filter bank is a pure MDCT and not an hybrid filter bank like in MP3
* Long windows are nearly twice as long as MP3 ones, providing better frequency resolution
* Short windows are smaller than MP3 ones, providing better transcients handling and less pre-echo
* Ability to toggle middle/side stereo on a subband basis instead of entire frame basis
* Ability to toggle intensity stereo on a subband basis instead of using it only for a contiguous group of subband.

This first part is mainly a removal of MP3 limitations, as AAC standard doesn't have to preserve compatibility. AAC also introduces some new tools over previous coding schemes:

* Temporal Noise Shaping (TNS) is a tool designed to control the location, in time, of the quantization noise by transmission of filtering coefficients
* Prediction is a tool designed to enhance compressibility of stationnary signals

*MPEG-4 AAC

The MPEG-4 standard adds some new tools in AAC, in order to improve coding quality at low bitrates:

* Perceptual Noise Substitution (PNS) allows to replace coding of noise-like parts of the signal by some noise generated on the decoder side
* Long Term Prediction (LTP) is once again a prediction tool.This one requires less computation power than the one used in MPEG-2 AAC, while providing comparable coding performance