Editing G.711 (section)

== G.711.1 ==
G.711.1 ''"Wideband embedded extension for G.711 pulse code modulation"'' is a higher-fidelity extension to G.711, ratified in 2008 and further extended in 2012.<ref name="g711-1-2012">{{citation |publisher=ITU-T |date=2012 |url=http://www.itu.int/rec/T-REC-G.711.1/en |title=G.711.1 : Wideband embedded extension for G.711 pulse code modulation |access-date=2022-12-24}}</ref>

G.711.1 allows a series of enhancement layers on top of a raw G.711 core stream (Layer 0): Layer 1 codes 16-bit audio in the same 4kHz narrowband, and Layer 2 allows 8kHz [[wideband]] using [[MDCT]]; each uses a fixed 16&nbsp;kbps in addition to the 64&nbsp;kbps core. They may be used together or singly, and each encodes the differences from the previous layer. Ratified in 2012, Layer 3 extends Layer 2 to 16kHz "superwideband," allowing another 16&nbsp;kbps for the highest frequencies, while retaining layer independence. Peak bitrate becomes 96&nbsp;kbps in original G.711.1, or 112&nbsp;kbps with superwideband. No internal method of identifying or separating the layers is defined, leaving it to the implementation to packetize or signal them.<ref>{{citation |url=http://www.eurasip.org/Proceedings/Eusipco/Eusipco2008/papers/1569105406.pdf |title=Noise shaping in an ITU-T G.711-Interoperable embedded codec |author=Lapierre |date=2008-08-25 |access-date=2024-06-11|display-authors=etal}}</ref><ref>{{citation |url=http://www.eurasip.org/Proceedings/Eusipco/Eusipco2008/papers/1569104469.pdf |title=G. 711.1: a wideband extension to ITU-T G. 711 |author=Hiwasaki |date=2008-08-25 |access-date=2024-06-11|display-authors=etal}}</ref>

A decoder that doesn't understand any set of fidelity layers may ignore or drop non-core packets without affecting it, enabling graceful degradation across any G.711 (or original G.711.1) telephony system with no changes.

Also ratified in 2012 was G.711.0 lossless extended to the new fidelity layers. Like G.711.0, full G.711 backward compatibility is sacrificed for efficiency, though a G.711.0 aware node may still ignore or drop layer packets it doesn't understand.