Phase 1 of the DRED integration (docs/PRD-dred-integration.md). The Opus
encoder now emits DRED (Deep REDundancy) bytes in every packet, carrying
a neural-coded history of recent audio that the decoder can use to
reconstruct loss bursts up to the configured window. Opus inband FEC
(LBRR) is disabled because DRED does the same job better and running both
wastes bitrate on overlapping protection.
Tiered DRED duration policy per PRD:
Studio (Opus 32k/48k/64k): 10 frames = 100 ms
Normal (Opus 16k/24k): 20 frames = 200 ms
Degraded (Opus 6k): 50 frames = 500 ms
Each profile switch (via adaptive quality) updates the DRED duration to
match the new tier. A 5% packet_loss floor is applied whenever DRED is
active, because libopus 1.5 gates DRED emission on non-zero packet_loss.
Real loss measurements from the quality adapter override upward.
Escape hatch: AUDIO_USE_LEGACY_FEC=1 reverts the encoder to Phase 0
behavior (inband FEC Mode1, DRED off, no loss floor). Read once at
OpusEncoder::new; call-scoped, not re-read mid-call. Trait-level
set_inband_fec becomes a no-op in DRED mode to preserve the invariant
even if external callers forget.
Observations from the bitrate probe test (dred_mode_roundtrip_voice_pattern):
DRED mode: 3649 bytes/sec (~29.2 kbps) on Opus 24k + 300 Hz sine
Legacy mode: 2383 bytes/sec (~19.1 kbps)
Delta: +10.1 kbps
The delta is considerably larger than the "+1 kbps flat" figure I carried
into the PRD from hazy memory of published DRED benchmarks. Likely because
the input (300 Hz sine) is very compressible so the base Opus rate in
legacy mode is well below the 24 kbps target, making the delta look
disproportionate. Signal-dependent — real speech would probably show a
different ratio. If production telemetry shows the overhead is excessive,
we can cut DRED duration on the normal tier from 200 ms to 100 ms as a
first tuning lever. Not blocking Phase 1 since the test still passes
within the reasonable 2000–8000 bytes/sec bounds.
Test changes (+8 tests, total wzp-codec: 61 passing):
- dred_duration_for_studio_tiers_is_100ms (per-profile policy)
- dred_duration_for_normal_tiers_is_200ms
- dred_duration_for_degraded_tier_is_500ms
- dred_duration_for_codec2_is_zero
- default_mode_is_dred_not_legacy (sanity check on fresh construction)
- dred_mode_roundtrip_voice_pattern (observes DRED bitrate, asserts bounds)
- profile_switch_refreshes_dred_duration (verifies set_profile updates DRED)
- set_inband_fec_noop_in_dred_mode (trait-level inband FEC no-op)
Verification:
- cargo check --workspace: zero errors, no new warnings
- cargo test -p wzp-codec: 61/61 passing (53 pre-Phase-1 baseline + 8 new)
- Empirical DRED bitrate observed via `rtk proxy cargo test
dred_mode_roundtrip_voice_pattern -- --nocapture`
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Phase 0 of the DRED integration (docs/PRD-dred-integration.md). No behavior
change: inband FEC stays ON, no DRED, same bitrate, same quality. This
commit unblocks Phase 1+ by getting us onto libopus 1.5.2 where DRED lives.
Rationale for going straight to a custom DecoderHandle: opusic-c::Decoder's
inner *mut OpusDecoder pointer is pub(crate), so we cannot reach it for the
Phase 3 DRED reconstruction path. Running two parallel decoders (one for
audio, one for DRED) would drift because the DRED decoder wouldn't see
normal decode calls. Single unified DecoderHandle over raw opusic-sys is
the only correct architecture, so we build it in Phase 0 rather than
rewriting opus_dec.rs twice.
Changes:
- Cargo.toml (workspace + wzp-codec): remove audiopus 0.3.0-rc.0, add
opusic-c 1.5.5 (bundled + dred features), opusic-sys 0.6.0 (bundled),
bytemuck 1. Pinned exactly for reproducible libopus 1.5.2.
- opus_enc.rs: rewritten against opusic_c::Encoder. Argument order for
Encoder::new swapped (Channels first). set_inband_fec(bool) now maps
to InbandFec::Mode1 (the libopus 1.5 equivalent of 1.3's LBRR). encode
uses bytemuck::cast_slice<i16,u16> at the &[u16] boundary.
- dred_ffi.rs (new): DecoderHandle wrapping *mut OpusDecoder directly via
opusic-sys. Owns the allocation, frees on Drop. Exposes decode,
decode_lost, and a pub(crate) as_raw_ptr() for the future Phase 3 DRED
reconstruction. Send+Sync justified via &mut self access discipline.
- opus_dec.rs: rewritten as a thin AudioDecoder impl over DecoderHandle.
Behavior identical to pre-swap.
Verification (Phase 0 acceptance gates):
- cargo check --workspace: clean (30 pre-existing warnings in jni_bridge.rs
unrelated to this work; zero in changed files).
- cargo test -p wzp-codec: 53 tests pass (50 pre-swap + 6 new: 3 in
dred_ffi.rs for DecoderHandle lifecycle, 3 in opus_enc.rs for version
check and roundtrip).
- linked_libopus_is_1_5 test asserts opusic_c::version() contains "1.5" —
hard signal that the swap landed correctly.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Adds three new codec IDs (Opus32k=6, Opus48k=7, Opus64k=8) and
corresponding STUDIO_32K, STUDIO_48K, STUDIO_64K quality profiles.
All use 20ms frames with minimal FEC (10%) for maximum quality on
good networks.
Updated across: wire protocol (codec_id.rs), encoder/decoder
(opus_enc/dec.rs), adaptive codec switch (call.rs), CLI
(--profile studio-64k), desktop engine + UI slider (8 quality
levels from Studio 64k green to Codec2 1.2k red).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- New wzp-android crate with Oboe C++ backend, lock-free SPSC ring buffers,
engine orchestrator, codec pipeline, and Android Gradle project structure
- AEC (NLMS adaptive filter), AGC (two-stage with fast attack/slow release),
windowed-sinc FIR resampler replacing linear interpolation (wzp-codec)
- Opus encoder tuning: complexity 7 default, set_expected_loss support
- Mobile jitter buffer: asymmetric EMA (fast up/slow down), handoff spike
detection with 2s cooldown, configurable safety margin
- Network-aware quality control: cellular-specific thresholds, faster
downgrade on cellular, proactive tier drop on WiFi→cellular handoff,
FEC ratio boost during network transitions
- Handoff detection in PathMonitor via RTT jitter spike analysis
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
