In September Apple's CEO Tim Cook once again spoke about the horrible state that television is in today with Charlie Rose without committing to what Apple may one day introduce to bring television into the digital age. One area that Apple has been known to be working on regarding television is next generation audio. We covered one such patent application back in January 2013. Today, the US Patent & Trademark Office published a patent application from Apple that reveals yet another aspect to advanced audio that technically relates to the new Home Theater 3D sound standard that is now under development.
Apple's Patent Background
Apple states that Dynamic Range Control/Compression (DRC) reduces the dynamic range of an audio signal by some amount by (1) making soft parts in the audio signal louder; (2) making loud parts in the audio signal softer; or (3) both making soft parts louder and making loud parts softer. A reduced dynamic range may be desirable in several situations, including for audio playback systems that can only reproduce a small dynamic range while maintaining low distortions, listening environments with distracting sounds, and in situations where the listener does not want to distract others.
Although, DRC is an important feature for today's audio codecs, several recent audio codecs do not support DRC. For example, DRC is absent in the Unified Speech and Audio Coding (USAC) standard by the Moving Picture Experts Group (MPEG). Advanced Audio Coding (AAC) incorporates a DRC tool, but this DRC tool has drawbacks, including limited time resolution and aliasing distortions. Apple's patent invention provides a solution to this problem.
Apple notes that their invention relates to a system and method for encoding and applying Dynamic Range Control/Compression (DRC) to an audio signal. Furthermore, the system and method described in their patent application takes into account the DRC requirements of new codecs under development in MPEG-H (3D Audio). For the record, MPEG-H primarily relates to multiple speakers in a home theater promoting immersive audio.
Apple's patent FIG. 1 shows a block diagram of compression post processing following an audio decoder.
If you're a sound engineer or the like, you'll likely appreciate Apple's invention beyond it being advantageous for future home theater systems. You could check out Apple's patent application 20140297291 titled "Metadata Driven Dynamic Range Control" (DRC), here.
Apple credits Frank Baumgarte as the sole inventor of patent application 20140297291which was filed in Q1 2014. Considering that this is a patent application, the timing of such a product to market is unknown at this time.
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