WMA 192 CBR Approx. Equivalent?
Reply #16 – 2006-11-29 13:13:45
... all I'm wondering is where in the scale of quality does WMA 192 CBR fall? Is it better than the AAC 128kbit that iTunes puts out or about the same. Is it about the same as LAME MP3 Preset:Medium? My findings (if they are meaningful for you) show that wma@192cbr is definitely better than iTunes aac@128cbr and Lame mp3@V4(Medium). It is inferior to aac-family-encoders @192 only (except for iTunes) as wma quality is more dependable on samples used for testing. Unfortunately several recent outliers have just spoiled results of Nero aac@192 at SoundExpert but the defeat is temporary. Let me also add some oil to the flame. Here is an excerpt from future article (draft) aimed to explain to Mr. Joe Average how SoundExpert testing works. This part devoted to “transparency margin” discussed above.… such analytically computed ratings are usually located above 5th grade on impairment scale. This could be interpreted as quality margin or quality headroom of an audio device because the artifacts are beyond the threshold of human audibility. You may ask what the purpose of the margin is if sound artifacts are inaudible already. There are at least four reasons why this is important: • In general case perceived audio quality of a device/technology depends on sound samples used for testing. Theoretically a listening test has to be performed with infinite number of sound samples in order to prove for sure that tested device will not produce unexpected “surprises” on real-world audio material. In practice a limited set of typical or problem (“killer”) sound samples is used. Then testing results are just generalized on all audio. Obviously quality margin makes that generalization more grounded and lessens the probability of getting artifacts on audio material not used during the test. • Very often audio devices/technologies are used in chains – connected one after another. In most cases this accumulates sound degradation throughout the chain. Quality margin of each device is highly desirable to lessen overall distortion level. • Such post processors as equalizers, spatializers, SRS and many others usually reveal sound artifacts inaudible in “normal” cases. Some quality headroom helps to use all those popular sound enhancements safely without danger of discovering drawbacks of other audio components. • Human hearing abilities differ from person to person. Averaged results of any listening test have to be applied with great caution to someone’s particular situation especially if that someone has “golden ears”. Such person needs audio equipment with sufficient quality margin in order to be satisfied. Sound quality margin is not something completely new. Well known technical audio parameter – THD is used quite similarly: measured on pure sine wave and corresponding to perceived audio quality not very well it have to be as low as possible – far beyond human abilities to hear such low distortions of pure waves.