Yue Lang

Parametric stereo coding scheme with a new downmix method and whole band inter channel time/phase differences

This paper presents a novel low bit rate parametric stereo coding scheme which uses whole band inter-channel time difference (WITD) and whole band inter-channel phase difference (WIPD) together with a new effective downmixing method. The inter-channel level differences and inter-channel phase differences are also employed in the proposed stereo coding to further improve the quality in an embedded structure. This scheme is applied to the stereo extension of ITU-T G.722 at 56+8 kbits/s with a frame length of 5 ms. Listening test results are provided to assess the quality of the proposed downmixing method and WITD/WIPD coding scheme separately.

G.722 annex D and G.711.1 Annex F - New ITU-T stereo codecs

This paper presents the two new ITU-T Recommendations G.722 Annex D and G.711.1 Annex F, which are stereo extensions of the wideband codecs ITU-T G.722 and G.711.1 and their superwideband extensions (G.722 Annex B and G.711.1 Annex D). An embedded scalable structure is used to add stereo extension layers on top of the wideband or superwideband core coding. Wideband stereo modes are supported at the bit rates of 64/80 and 96/128 kbit/s for G.722 and G.711.1 (respectively), while superwideband stereo modes are supported at 80/96/112/128 and 112/128/144/160 kbit/s. The parametric stereo coding model is based on a frequency domain downmix, wideband inter-channel differences estimation, quantization and synthesis, low complexity coherence analysis and synthesis, stereo transient detection and stereo post-processing. An overview of formal ITU-T characterization listening tests illustrates the performance of these codecs.