Replace the JSON f32 array (~7.5 KB/frame) with a named SSE event "b"
carrying base64-encoded i8 bins (~1.4 KB/frame, ~5x reduction):
event: b
data: {center_hz},{sample_rate},{base64_i8_bins}
1 dB per step covers the -128…+127 dBFS display range, sufficient for
visualization. RDS is stripped from the spectrum frame and emitted as a
separate named "event: rds" only when the payload changes. The JS
decoder uses atob() + sign-extension to reconstruct the float bin array.
A minimal inline base64 encoder is added server-side (no new crate).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>
sjg
75355c75a5
