[Speex-dev] Question about UWB

[John Ridges]

Hi all,

One question that I hope someone on the list just knows the answer to 
without having to delve too deeply into the code: How does UWB mode 
divvy up the bandwidth and pack it in the bitstream? I know from the 
documentation that WB mode codes the first 0-4K kHz band as a Narrowband 
packet, and then adds on the 4-8 kHz band coded separately (so that a NB 
decoder can decode a WB bitstream by just ignoring the second band; 
rather clever I thought), but it doesn't describe how UWB mode works. 
Does UWB keep the 0-4 kHz NB packet, and then add a 4-16 kHz UWB packet? 
Or does UWB contain both a NB and WB packet, and add a 8-16 kHz part? Or 
something completely different? I'm just trying to figure out which 
decode modes will decode which encode mode bitstreams. Thanks,

--John Ridges