av_channel_layout_copy() documents that it always uninitialises the
destination first, and av_channel_layout_uninit() calls av_freep() on
u.map. Declaring the layouts without {} therefore handed free() whatever
pointer-shaped garbage occupied that stack slot.
Not theoretical: UT-103 aborted with "free(): invalid pointer" in about
1 run in 4. Zero failures in 40 runs after the fix, against 10 in 40
before it.
Two things kept it hidden, both worth remembering:
- It is stack-dependent, so it disappears under an AddressSanitizer
build and reads as a flake in the aggregate test binary, where the
case usually passes. ctest, which runs each case in its own process,
is what made it a reproducible failure rather than noise.
- UT-103 is the only test that reaches this branch, because it is the
only one whose input is stereo. The golden-vector tests use a mono
11025 Hz fixture chosen so the vector cannot depend on libswresample
— which is right, and means bit-exactness against the golden vector
is not evidence about the downmix path.
TRACES: IR-004 | SR-003
Implements the content-derived spectral-peak signature from
JRay-public-server/SPEC.md §3 so a truth file is self-identifying: 120 s
window centred on the media midpoint, mono at 11025 Hz, 4096/1024 Hann
STFT, 32 log-spaced bins over 300-3000 Hz, one byte per frame (5-bit peak
band + 2-bit energy class), base64, `v1:` prefix.
Audio decode is a second stream from the FFmpeg libraries the pipeline
already links for video; libswresample is added to the existing
ffmpeg_libs interface target. The FFT is written out rather than pulled
from a library for the same reason the plugin vendors one: the output has
to be bit-identical across two languages, so a dependency whose version
could change the numerics is a liability.
The server spec fixes the geometry but not enough to reproduce a byte
stream — Hann periodicity, band aggregation, the energy-class definition,
tie-breaking and the base64 alphabet are all unconstrained by it. Those
are pinned in audio_signature.hpp and mirrored in the golden fixture, so
the plugin can be implemented from the fixture alone.
IR-005: tests/fixtures/audio/ carries a deterministic 120 s tone (FLAC —
lossless, so identical PCM to the WAV make_fixture.py emits, and 3.5x
smaller in git) plus the signature it must produce, the decoded-PCM
checksum and the full parameter contract. That directory is the artefact
shared with the plugin repo; the PCM checksum is separate from the
signature so a codec-level difference is distinguishable from a DSP one.
IR-007: media under 120 s emits no signature. Same for a file with no
audio stream or one that will not open — UR-9 is an enhancement and must
never be able to break a fetch.
Verified against an independent Python reference implementation: same
bytes. All 32 bands and all 4 energy classes appear in the golden vector,
and the window-centring test wraps the fixture in 90 s of silence either
side and requires the golden value back.
Not wired into the truth-file output yet — that is the schema_version
bump under IR-002/IR-003 and is deliberately out of scope here.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
dtourolle
