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ITU-T G.722 Appendix IV

A low-complexity algorithm for packet loss concealment with G.722

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Ngày phát hành: 2007-07-00

Liên hệ
Packet loss concealment (PLC) algorithms, also known as frame erasure concealment algorithms, hide transmission losses in audio systems where the input signal is encoded and packetized, sent over a network, received and decoded before play out. PLC algorithms can be found in most standard CELP-based speech coders. The algorithm described here provides a method for [ITU-T G.722]. The decoder comprises three stages: lower sub-band decoding, higher sub-band decoding and quadrature mirror filter (QMF) synthesis. In the absence of frame erasures, the decoder structure is identical to G.722, except for the storage of the two decoded signals, of the high and low bands. In case of frame erasures, the decoder is informed by the bad frame indication (BFI) signalling. It then performs an analysis of the past lower-band reconstructed signal and extrapolates the missing signal using linear-predictive coding (LPC), pitch-synchronous period repetition and adaptive muting. Once a good frame is received, the decoded signal is cross-faded with the extrapolated signal. In the higher band, the decoder repeats the previous frame pitch-synchronously, with adaptive muting and high-pass post-processing. The ADPCM states are updated after each frame erasure. The PLC algorithm described in this appendix meets the same quality requirements as the PLC in Appendix III of [ITU-T G.722], but with a lower complexity. Almost no additional complexity is added compared with normal G.722 decoding (worst-case additional complexity is 0.07 WMOPS). An alternative quality-complexity trade-off is provided by Appendix III. This edition includes the revision of Appendix IV approved 07/2007, which corrects defects in the original C source code (Release 1.0.a) approved 11/2006. The revised C source code is labelled Release 1.1 and is available as an electronic attachment to this Appendix.
Số hiệu tiêu chuẩn
ITU-T G.722 Appendix IV
Tên tiêu chuẩn
A low-complexity algorithm for packet loss concealment with G.722
Ngày phát hành
2007-07-00
Trạng thái
Hết hiệu lực
Tiêu chuẩn tương đương
Tiêu chuẩn liên quan
ITU-T G.722 (1988-11)
7 kHz audio-coding within 64 kbit/s
Số hiệu tiêu chuẩn ITU-T G.722
Ngày phát hành 1988-11-00
Mục phân loại 33.040.20. Hệ thống truyền tin
Trạng thái Có hiệu lực
Thay thế cho
Thay thế bằng
ITU-T G.722 Appendix IV (2009-11)
A low-complexity algorithm for packet-loss concealment with ITU-T G.722
Số hiệu tiêu chuẩn ITU-T G.722 Appendix IV
Ngày phát hành 2009-11-00
Mục phân loại 33.040.20. Hệ thống truyền tin
Trạng thái Có hiệu lực
Lịch sử ban hành
ITU-T G.722 (2012-09)
7 kHz audio-coding within 64 kbit/s
Số hiệu tiêu chuẩn ITU-T G.722
Ngày phát hành 2012-09-00
Mục phân loại 33.040.20. Hệ thống truyền tin
Trạng thái Có hiệu lực
* ITU-T G.722 Appendix IV (2009-11)
A low-complexity algorithm for packet-loss concealment with ITU-T G.722
Số hiệu tiêu chuẩn ITU-T G.722 Appendix IV
Ngày phát hành 2009-11-00
Mục phân loại 33.040.20. Hệ thống truyền tin
Trạng thái Có hiệu lực
* ITU-T G.722 Appendix IV (2007-07)
A low-complexity algorithm for packet loss concealment with G.722
Số hiệu tiêu chuẩn ITU-T G.722 Appendix IV
Ngày phát hành 2007-07-00
Mục phân loại 33.040.20. Hệ thống truyền tin
Trạng thái Có hiệu lực
Từ khóa
Agreements * Analogue signals * CCITT * Coding (data conversion) * Communications * Encoding * International organizations * Telecommunication * Telecommunications * Transmission systems * Codification
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