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Don’t be fooled by mp3PRO

July 25, 2011

It’s long been known that the old record industry cynically resold back catalogue to music fans each time a new format came along. Why invest in developing new artists when you could resell Pink Floyd, The Beatles and Elvis?

Digital media arrived and started a revolution. Initially CDs were simply the latest medium with which to resell old music to the public. When recordable digital media arrived in the public domain the music industry freaked out.

Digital Audio Tape (DAT) was capable of recording at above CD sound quality. The record labels simply said they would never release anything in the format because they didn’t want people having the ability to accurately copy CDs. No releases meant no market for player/recorders. DAT rapidly became a format for recording studios only.

At the same time, there was a conceptual battle happening among music listeners. Did they want awesome sound quality or portability?

DVD Audio, which contained uncompressed, full surround, 24 bit, full bandwidth audio, lasted about a week. It was the nearest the public will ever get to the sound heard in a recording studio. The 5.1 audio on DVD films is 24 bit but has gone through some data compression. The stereo track is usually better, 24 uncompressed, but it’s only stereo.

The public voted for portability. The arrival of mp3 and, shortly thereafter, broadband Internet, killed decent audio for the general public. We chose crap but portable. The age of the mp3 was upon us.

We get used to crap. Every so often, I play a CD through my hifi or in my recording studio of some music I’ve been listening to in 320kbps format in my phone. I am always staggered by how much is missing from the mp3s. Sounds fine at the time – but go play the CD! There is no comparison.

Well, we’re about to be sold another pile of cack called mp3PRO. The name implies that it’s better than mp3, doesn’ t it? Basically, someone has come up with a way to make lower bit rate mp3s (lower than 128 kbps), which usually sound appalling, sound a bit better.

The reason that mp3s at these lower bit rates sound shit is that they run out of bits to compress the music in full audio bandwidth and with significant detail. The developers of mp3 had to decide whether their codec should produce mp3 music with distortion (coding artefacts) or with limited bandwidth. They opted for limited bandwidth. As a result, you experience lower bit rate mp3 as band-limited music with relatively little perceived distortion. All very clever.

To improve the sound quality of mp3 at lower bit rates, Coding Technologies has developed an enhancement technology that gives back to the sound the high frequency components. The technology is called ‘Spectral Band Replication’ (SBR). SBR is a very efficient method to generate the high frequency components of an audio signal.

Combining mp3 with the SBR enhancement technology generates an audio signal with high bandwidth at low bit rates. Mp3PRO is composed out of two components, the mp3 part for the low frequencies and the SBR or ‘PRO’ part for the high frequencies. Since the ‘PRO’ part requires only a few kbps, the format is still compatible with the original mp3 format. This fact allows existing mp3 players to play mp3PRO files. They simply ignore the PRO part.

So – don’t be fooled into thinking mp3PRO is somehow better than mp3 or is a later, higher quality, version. No, it’s a way to make poorer quality mp3s sound better. The files end up about half the size of an average quality mp3.

This new combined format will be a temporary stop gap until the mobile-player manufacturers start trying to out-do each other withproper, full quality audio downloads. With memory capacity and available bandwidth growing constantly and the advent of ‘cloud’ libraries, there is no reason (other than bloody-minded obstruction by the few remaining big record companies) for music not to be distributed in 24 bit WAV quality or even better multi-channel surround formats.

Broken Drum Records

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