Low-rate stream formats

[polygon]

When I'm using the BladeRF with a host that only supports USB2 the achievable sampling rates sometimes are too small. If I understand correctly, currently the 12 bit samples are transmitted as 16 bit with 4 bits unused (or as metadata in one mode). I want to suggest some new streaming modes that allow for higher reachable sampling rates by saving bandwidth.

The first idea is to pack two I/Q samples with 48 bits of data into three 16-bit integers. That should be relatively simple on the FPGA and host side. It would increase the possible samplerate by 33%.

The other idea is to truncate the lower four bit of each sample, effectively converting them to 8 bit resolution. Then, a full I/Q sample could be transmitted in a single 16 bit integer. That would increase the sampling rate by 50%. To remain compatible, the output could be scaled up to 12 bit again.