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7.40.0: TrueHD Atmos from the channel presentation, DTS:X standard presentation only (#731, #744) - #836
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… split by object energy (#731) The TrueHD path no longer mixes object signals into the layout. The decoder discards the matrix interpolation values and carries the stream's channel-based presentation (Dolby's 7.1 or 5.1 rendering of the same mix) alongside each block; BedSplitter divides every bed channel per STFT bin between the floor speakers it covers and the heights, by where the objects' energy lies, bounded by the bed and balanced per band towards a direct render. Elements are plain point sources. A 5.1 bed covers a 7.1 layout's sides and rears. The splitter's 2048-frame latency is drained before the encoder restarts elsewhere and at end of input, so no audio is lost there. AETHER_TRUEHD_REFERENCE_RENDER=1 keeps the exact decode and mix for measurements. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WJcXkGQrMiBPixVEFTSBJS
The bed bound now compares an element with its bed channels per band instead of per bin: in a single bin Dolby's mix can hold less than one element where several cancel, and the per-bin bound cut legitimate height content there. The balance only raises an output towards the direct-render estimate and never lowers it, since the elements' energies add up to less than a mix of them wherever they carry the same signal. Against the exact render on nine height-heavy windows of five films the heights went from -0.61 to -0.20 dB, the median misplaced energy from 0.54 to 0.38 %; on Unfold from 4.6 to 3.0 %, worst second 9.9 to 6.8 %. The LFE delay line was one hop longer than the split outputs' latency. Bridge tests run with and without the stream's bed; BedSplitterTests pin the split, the 5.1 bed on a 7.1 layout and the timeline. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WJcXkGQrMiBPixVEFTSBJS
…#731) Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WJcXkGQrMiBPixVEFTSBJS
…731) Never lowering let a split that over-allocates stand: on 72 windows of six films two scenes came out 1.5 dB loud in heights and surrounds (worst second 9.0 % misplaced). Lowering by a third of the gap in dB keeps the heights within about a dB of the exact render while those scenes drop to 5.3 and 5.7 %; Unfold stays at 3.3 % median, its second 9 left rear at 15.1 % against the reference's 14.5 %. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WJcXkGQrMiBPixVEFTSBJS
…a without ramps (#731) A block that arrives without the channel presentation before the splitter exists played through the renderer's mix; it is now silence, since a decoder that splits its bed plays nothing but the bed. Metadata updates are taken as they stand rather than ramped towards: the split's weights are smoothed over about 200 ms anyway, and on the measured windows nothing moved by more than 0.1 point. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WJcXkGQrMiBPixVEFTSBJS
…731) The exact decode and the size, snap, zone, screen and elevation mapping for TrueHD are now built only with the TrueHDReferenceRender trait. A shipped TrueHDObjectAudio build contains the bed split alone, and a decoder that is asked for the exact path without the trait traps. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WJcXkGQrMiBPixVEFTSBJS
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WJcXkGQrMiBPixVEFTSBJS
…or 9.1.6 With LibDTSX 3.0 the heights are removed from the 7.1 bed by the standard's own constant fold rather than the gains the stream's metadata states, and presentations with objects are refused, so they keep the channel bridge and play as 7.1. DTS:X is now rendered only into the layouts that carry its bed and four heights one to one (7.1.4, 9.1.6); any other layout keeps the channel bridge with a log line saying so. The decoder accepts the twelve standard channels and nothing else, so no DTS:X channel is ever panned. Docs, changelog and tests follow; the object tests are gone and the alternate sample's verdict is now a refusal. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WJcXkGQrMiBPixVEFTSBJS
…ion, DTS:X standard presentation only LibTrueHD 3.0.0 (bed companion, interpolation out of the default build) and LibDTSX 3.0.0 (standard presentation, constant height fold). Version sweep, changelog folded, README notes the pbxproj traits form. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WJcXkGQrMiBPixVEFTSBJS
…lakes fixed The FIFO's backpressure applied only while a segment had bytes left over. When a segment's last chunk was taken just under the ceiling, the next request went out at once with the buffer already over it, which is what made testFullBufferLetsTheCurrentSegmentFinishAndHoldsTheNextRequest flaky on CI (large loopback chunks). The producer now waits for room between segments either way; a new test builds the case deterministically (fails 3/3 before, passes 3/3 after). ItemSwapStillTests' fixture writer counted a starved test task as a stalled AVAssetWriter: both tracks were ready, but the loop had not run for the 20 s on a loaded runner. A stall now also needs 1000 idle polls. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WJcXkGQrMiBPixVEFTSBJS
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Summary
BedSplitter). No object signal reaches an output. Objects are decoded without matrix interpolation (LibTrueHD 3.0.0, the interpolating decode is not in its default binary) and taken as points, without size, snap, zones, screen anchoring, elevation switch or metadata ramps. The exact render it is measured against lives behind the measurement-onlyTrueHDReferenceRendertrait.Measurements
Tests
swift test: default configuration 4614 swift-testing tests plus XCTest green; withTrueHDObjectAudio,DTSXObjectAudio4682 plus XCTest green.🤖 Generated with Claude Code
https://claude.ai/code/session_01WJcXkGQrMiBPixVEFTSBJS