TestBufferedStreamer_BasicStream flaked under -race (got 1256/1512 vs
1000 expected). The streamer injects silence frames by design when its
ring buffer momentarily underruns; under the race detector the consumer
outran read-ahead and received mid-stream 256-sample silence frames. The
collection loop only skipped leading silence, so those frames were
counted as data.
Skip all zero frames, matching the test's own drain loop — real samples
always start at 1.0, so any zero is injected silence, never source data.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>