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back to article Ads police say 128Kbps AAC is CD quality

Nokia - unlike Creative - has been allowed by UK advertising watchdog the Advertising Standards Authority (ASA) to claim that its Nokia 5300 Xpress Music phone can deliver CD quality sound from compressed, lossy audio formats. The ASA today said it had ruled against a complaint that Nokia's claim was misleading. The complainant …

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Hmmm

So what is to stop Creative from grabbing a random group of 20 freinds and co-workers and getting them to listen to it and say they think the sound is better than CD quality ??

What a load of rubbish, yet another case of the regulators bowing down to corporate pressure!!!

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Anonymous Coward

AAC at 160kbps

Using ffmpeg to encode tracks ripped from an audio CD to AAC at 160kbps encapsulated in a .m4a container provided quite a surprise. The transcoding process didn't need the full 160kbps in order to encode the audio!

Certainly, listening to AAC @ 128kbps one has the impression that the sound is every bit as good as (if not better than) mp3 @ 160kbps.

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Rob

Sound quality is in the ear of the beholder

As someone who worked on the development of the reference psychoacoustic model for AAC circa 1998-2000, I must say that the complainant to the Nokia ad was somewhat naive in their assessment that that AAC cannot be the same listening quality as a CD.

Yes, the transported bit-rates are starkly different. This is in fact the objective!

My point is this: during the circa 2000 MPEG listening tests (which were conducted in the manner described in the ITU-R BS1116 standard "Methods for the subjective assessment of small impairments in audio systems including multichannel sound systems"), we found that the AAC low-complexity profile appeared transparent to the 90% of the 100+ listeners @96kb/s joint stereo. This is using the MPEG critical audio items from the SQAM library.

Therefore, anybody who claims to hear the difference between a CD and the equivalent AAC stream @128kb/s is a big fat liar.

Nokia may want to consider referring to "listening quality" in their adds in future.

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Anonymous Coward

What a bunch of lies!

It's a known fact that any lossy compression scheme/algorithm being ITU-T / MPEG Group one or other is developed with listening/watching tests and the involved parameters (transients, high/low frequencies pass/cut-off and so on...) get adjusted on the average best perception results that the group tests gives to developers. All MPEG Codecs were built this way... but claiming that that's enough to tell anyone that a lossy compression format is the same as the lossless original source it's just silly marketing and a lie.

It's just not true, otherwise there would be no need to perform perceptive tests on a group of people to find out the best parameters values when working in the frequency domain, you know...

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Says who?

Which 90-year old coots did they use to test this?

Are we playing CD music and CD-quality music through the inbuilt Nokia speakers? (urgh!)

160Kbps AAC has to be the bare minimum standard for CD-quality sound.

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Close but not good enough

Well claiming it's not CD quality because of the bit rate is an absurd technicality, going by listening quality is a fair test. But I'm a bit hessitant to say 128Kbit AAC is truly CD quality, but I will admit AAC quality per bit ratio is very high, right next to Ogg Vorbis.

If they had said 160Kbit or 196Kbit was equivalent to CD quality, I might be satisfied with that, but somehow this jusi smells of some kind of standard Apple created with iTunes.

So what's next, will 256Kbit AAC be called HD Audio?!

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