Ads police say 128Kbps AAC is CD quality
Nokia 1, Consumers 0
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 said compressed files played on the 5300 did not deliver the same bit-rate as a CD does and therefore the sound can't be said to be CD quality.
That's essentially the complaint raised against advertising employed by Creative to promote its Xmod sound system, though to be fair Creative over-egged it a tad by alleging its kit delivered "better than CD quality". Tha ASA ruled against Creative.
Most folk will say a 128Kbps AAC file can't possibly deliver the same audio quality as the 1411Kbps CD, but Nokia claimed that since an ISO survey, Report on the MPEG-2 AAC Stereo Verification Tests, found listeners largely unable to distinguish between the two, 128Kbps AAC could be said to be of CD quality - and a 160Kbps playable on the 5300 certainly would.
"We considered that readers [of the ad] would interpret the claim 'CD quality sound' to mean that when they listened to files played on the Nokia 5300 Xpress Music the sound would be indistinguishable from CD sound," the ASA said.
"We considered the tests provided proved that most listeners were unable to distinguish between compressed AAC files encoded at 128Kbps and CD sound. We concluded that Nokia had substantiated the claim 'CD quality sound' and it was unlikely to mislead." So there, cloth-ears...
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.
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?!
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!!!
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.
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.