User uploaded a Vert-heavy event (JQ0) and a Mic-heavy event (V70).
Those two were exactly what was needed to crack the next piece:
- 00 NN block = run-length-encoded zero deltas in the current channel.
Append NN copies of the current cumulative value (no change).
- find_data_start now recognizes 00 NN as a valid first tag (some events
begin with a leading 00 NN RLE block).
- decode_tran_initial now decodes the FULL segment 0 (not just the first
data block).
Results across 5 fixture events:
- M529LL1A.SP0 (loud-all-channels) : 510 / 510 ✓
- M529LL1L.JQ0 (Vert-heavy) : 510 / 510 ✓
- M529LL1L.V70 (Mic-heavy) : 510 / 510 ✓
- M529LL1A.SV0 (loud-from-start) : 58 / 58 ✓
- M529LL1A.SS0 (loud-from-start) : 42 / 502 (stops at first 30 04)
The 30 04 block (only seen in loud-from-start events) hasn't been
decoded yet — likely a channel-switch marker for the high-amplitude
regime.
Also discovered: segment header (40 02) payload bytes [0:2] = T_delta
at first sample of new segment, [6:8] = byte length to next segment.
Multi-segment Tran decoding still diverges after sample 512 because
the per-segment channel ordering after the header is unknown.
Tests: 40 pass (up from 36).
Files:
- minimateplus/waveform_codec.py: find_data_start fix, RLE handling,
full segment-0 decode in decode_tran_initial
- tests/test_waveform_codec.py: synthetic RLE test, full segment 0
tests for JQ0 and V70
- tests/fixtures/5-11-26/: M529LL1L.JQ0, M529LL1L.V70 + TXT exports
- docs/instantel_protocol_reference.md §7.6.1: RLE + segment-header docs
User uploaded 3 high-amplitude events (PPV 6-7 in/s — shook the geophone
hard) to decode-re/5-11-26/. These cracked the Tran codec:
- Preamble bytes [3:5] and [5:7] = Tran[0] and Tran[1] as int16 BE
in 16-count units (LSB = 0.005 in/s). Confirmed across all 7
fixtures.
- First data block carries Tran deltas from sample 2 onward:
* 10 NN block: NN/2 bytes of payload, each byte = two 4-bit signed
nibble deltas (high nibble first)
* 20 NN block: NN int8 signed deltas
Verified 22+42+46 = 110 Tran samples across SP0/SS0/SV0 with 0 errors
against BW's ASCII export.
Why the earlier 96-combination brute force failed: the quiet 5-8
events all had T[0] = T[1] ≈ 0 so the preamble's per-channel encoding
was undetectable. Loud events made the encoding obvious.
What's solved:
- minimateplus.waveform_codec.decode_tran_initial: returns first
N Tran samples in 16-count units for any body.
- Walker length formula for in-data 30 NN blocks (NN*2 instead of NN*4).
- Walker now handles bodies that start with 20 NN (in addition to 10 NN).
What's still open:
- Tran past the first data block (multi-block channel switching).
- Vert / Long / MicL channel encodings.
- Walker correctness past offset ~427 in event-b.
Tests: 36 pass. decode_waveform_v2 still returns None — the full
multi-channel decoder is not wired up. decode_tran_initial is the
new verified entry point.
Files: minimateplus/waveform_codec.py, tests/test_waveform_codec.py
(adds 5-11-26 fixtures + decode_tran_initial tests), and
docs/instantel_protocol_reference.md §7.6.1 (Tran codec spec).
Claude