Otázka.:
What is mp3PRO? It a similar MP3 or not?
Odpověď:
To improve the sound quality of mp3 at lower bit rates, Coding Technologies has developed an enhancement technology that gives back 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. The SBR technology is key to mp3PRO.
Spectral band replication (SBR) is a technology to enhance audio or speech codecs, especially at low bit rates
It can be combined with any audio compression codec: the codec transmits the lower frequencies of the spectrum and SBR creates associated higher frequency content based on the lower frequencies and transmitted side information.
When applicable, it involves reconstruction of a noise-like frequency spectrum by employing a noise generator with some statistical information (level, distribution, ranges), so the decoding result is not deterministic among multiple decoding processes of the same encoded data.
Both ideas are based on the principle that the human brain tends to consider high frequencies to be either harmonic phenomena associated with lower frequencies or noise, and is thus less sensitive to the exact content of high frequencies in audio signals.
Combining mp3 with the SBR enhancement technology generates an audio signal with high bandwidth at low bit rates. mp3PRO, the resulting audio format 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 could be done in a way that it is still compatible with the original mp3 format. This fact allows existing mp3 players to play mp3PRO files. They simply ignore the PRO part. The only requirement is that they also have to support sampling rates of 16, 22.5 and 24 kHz along with 32, 44.1 and 48 kHz. While all (mp3 standard compliant) software players fulfil this requirement, not all portable and CD/DVD players do.
To learn whether your mp3 player is capable to play mp3PRO files, please check with its manual or manufacturer.
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