Invention Grant
- Patent Title: Bitrate constrained variable bitrate audio encoding
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Application No.: US13031963Application Date: 2011-02-22
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Publication No.: US08442838B2Publication Date: 2013-05-14
- Inventor: Shyh-Shiaw Kuo , Hong Kaura , William G. Stewart
- Applicant: Shyh-Shiaw Kuo , Hong Kaura , William G. Stewart
- Applicant Address: US CA Cupertino
- Assignee: Apple Inc.
- Current Assignee: Apple Inc.
- Current Assignee Address: US CA Cupertino
- Agency: Blakely, Sokoloff, Taylor & Zafman LLP
- Main IPC: G10L19/00
- IPC: G10L19/00 ; G10L19/02

Abstract:
A hybrid audio encoding technique incorporates both ABR, or CBR, and VBR encoding modes. For each audio coding block, after a VBR quantization loop meets the NMR target, a second quantization loop might be called to adaptively control the final bitrate. That is, if the NMR-based quantization loop results in a bitrate that is not within a specified range, then a bitrate-based CBR or ABR quantization loop determines a final bitrate that is within the range and is adaptively determined based on the encoding difficulty of the audio data. Excessive bitrates from use of conventional VBR mode are eliminated, while still providing much more constant perceptual sound quality than use of conventional CBR mode can achieve.
Public/Granted literature
- US20110145004A1 BITRATE CONSTRAINED VARIABLE BITRATE AUDIO ENCODING Public/Granted day:2011-06-16
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