User report: every downloaded track in an album came out with
``replaygain_track_gain: +52.00 dB`` regardless of actual loudness.
Root cause: the parser at ``core/replaygain.py:79`` used
``re.search('I:\s+...')`` which returns the FIRST match. ffmpeg's
ebur128 filter emits ``I:`` per measurement window (running partial
integrated loudness) AND in a final Summary block. The first
per-window reading is at t=0.5s — almost always ~-70 LUFS because
nearly every track starts with silence / encoder padding. So:
gain = RG2_reference - lufs = -18 - (-70) = +52.00 dB
…on EVERY track. Same regex pattern, same first per-window match,
same +52 dB written to every file's REPLAYGAIN_TRACK_GAIN tag.
Verified by running ffmpeg ebur128 against a real generated FLAC
and inspecting the stderr output — first per-window line at t=0.5s
shows ``I: -70.0 LUFS`` (silent intro), and the Summary block at
the end shows the real integrated value (e.g. ``I: -27.8 LUFS``
for the test sine wave). Old code captured the -70.0 reading.
Fix: anchor LUFS parsing to the ``Summary:`` block via
``stderr.rfind('Summary:')``. The Summary block is always emitted
last and contains the authoritative final integrated loudness.
Peak parsing already worked correctly (per-window output uses
``TPK:``/``FTPK:`` labels; only the Summary uses ``Peak:``), but
applied the same Summary anchor for consistency.
Defensive fallback: if no Summary block is present (truncated
output / unusual ffmpeg version), use the LAST per-window reading
instead of the first. Still better than the buggy first-window
behavior.
Smoke verified end-to-end: a freshly-generated FLAC of a -24 dBFS
sine wave now reports LUFS=-27.80, gain=+9.80 dB (correct, was
+52.00 before fix).
Tests: ``tests/test_replaygain_summary_parse.py`` — 7 cases pinning
the parser behavior with realistic ffmpeg ebur128 stderr samples:
- Summary value parsed correctly even when first per-window is -70
- Resulting gain is realistic (NOT +52)
- Two tracks with same first per-window but different summaries get
different LUFS (regression assertion for "all tracks same gain")
- Per-window reading higher than Summary doesn't leak through
- Fallback to last per-window when Summary absent
- Clean RuntimeError raised when no LUFS values anywhere
- Peak still correctly anchored to Summary
Verified: full suite 1800 pass (7 new), ruff clean.
WHATS_NEW entry under '2.4.2' dev cycle.
776d195f71
