foo_input_joc

foobar2000 input component for E-AC-3 JOC (Dolby Atmos) files: the JOC objects are rendered to binaural (HRTF) or to a speaker layout up to 7.1, in real time.

Two files with the same name pay for the whole thing: joc_core's C++ sources are copied into kernel/ and compiled straight into the component, so there is nothing to install beside foo_input_joc.dll.

What it does

1. Reads the E-AC-3 syncframes and decides from the bitstream whether the file really carries JOC (an EMDF container holding both the OAMD and the JOC payload).
2. A file without JOC is handed back to foobar2000 with exception_io_unsupported_format, so the built-in E-AC-3 decoder plays it — this component never decodes plain E-AC-3.
3. A JOC file is decoded as: the syncframes go to the renderer as metadata, the 5.1 core PCM comes from ffmpeg, and the renderer pairs them (one syncframe : 1536 bed samples) and produces the output PCM, which is handed back to foobar2000.

.eac3 file
  ├─ JOC check (src/eac3_scan.cpp)  ─── no JOC ──▶ built-in E-AC-3 decoder
  └─ JOC
      ├─ syncframes ────────────────────▶ renderer metadata
      └─ ffmpeg -ac 6 -c:a pcm_f32le ───▶ 5.1 core PCM ──▶ renderer bed
                                                             │
                                                             ▼
                                                    2 ch or ≤7.1 PCM ──▶ foobar2000

Repository layout

Path	Contents
kernel/	Copy of the joc_core C++ sources (include/ + src/) and joc_kernel.vcxproj, the static library the component links
src/eac3_scan.*	Syncframe walk and the JOC bitstream test
src/joc_decode.*	Decode engine: starts ffmpeg, drives the renderer, handles the end of stream. No foobar2000 headers, so it also builds into the offline tools
src/input_joc.cpp	The foobar2000 input: format recognition, yielding, get_info, initialize, run
src/settings.*	Configuration values and their environment overrides (development only)
src/prefs.cpp, src/prefs.rc	The preferences page
src/log.*	Diagnostic log written next to the DLL
tests/	Offline tools: bitstream self-test and cross-check against the renderer, render harness, preferences-page layout check
tools/	SDK fetch, build, package, deploy, unattended test bed run

Build

pwsh -File tools/setup_sdk.ps1          # official SDK into SDK/, pinned to target 1.5/1.6
pwsh -File tools/build.ps1              # Win32 -> build\Win32\foo_input_joc.dll
pwsh -File tools/build.ps1 -Platform x64
pwsh -File tools/package.ps1            # both, packaged into dist\*.fb2k-component

Release-Static uses the static CRT (/MT); /fp:precise is required and must not be changed. foo_input_joc.vcxproj builds kernel\joc_kernel.vcxproj first through a project reference. The copied kernel sources are compiled with JOC_STATIC / EJOC_STATIC so their entry points are neither imported nor exported.

Install

Either drop dist\foo_input_joc-<version>-<arch>.fb2k-component onto foobar2000 (or use Preferences → Components → Install), or copy foo_input_joc.dll into <profile>\user-components\foo_input_joc\. The per-component subdirectory is required: a DLL lying directly in user-components\ is not scanned. 1.6 is 32-bit, 2.x ships both, and a DLL of the wrong architecture is silently ignored.

tools/deploy.ps1 -TestBed <path to portable foobar2000> does the manual variant, and tools/run.ps1 -TestBed <path> -Play <file> runs it unattended and prints the log. Always let foobar2000 exit through /exit; a force-killed instance leaves a <profile>\running marker behind and the next start then refuses to load any user component.

Settings

Preferences → Tools → JOC decoder:

• Output — binaural, or a speaker layout from 2.0 to 7.1;
• Binaural mode (near / mid / far) and the room tail in seconds;
• HRTF source — a SOFA file or a Rosella .personalized_headphone model. Leave the path empty to use the default location <component directory>\HRTF\: binaural.sofa or binaural.personalized_headphone;
• Gain — a switch plus a value in dB. Binaural rendering can exceed full scale on material that does not clip in the core mix, so attenuation belongs here;
• the ffmpeg executable to use.

Nothing on the page is disabled; the status line states what is in effect.

HRTF data is not distributed with this repository. A SOFA measurement set or a personalised headphone model is supplied by whoever runs the component (and is listed in .gitignore so it cannot be committed by accident). Speaker layouts and every offline test except binaural rendering work without one; binaural rendering without an HRTF fails with a message naming the file it looked for.

Environment overrides

Development only: they override the stored settings for one run and every use is logged. JOC_OUTPUT, JOC_LAYOUT, JOC_HRTF, JOC_HRTF_SOURCE, JOC_BINAURAL_MODE, JOC_GAIN_DB, JOC_GAIN_ENABLED, JOC_TAIL_SECONDS, JOC_OBJECT_DELAY, JOC_THREADS, JOC_FFMPEG, JOC_LOG.

Known limitations

• ADM BWF output is not implemented.
• Containers (.m4a, .mkv) are not claimed: only bare .eac3 / .ec3 streams.
• The room tail is returned in full; the reference command-line renderer additionally trims trailing samples below a threshold, so its output can be shorter.
• x86 and x64 do not produce bit-identical binaural output (last-bit differences): the renderer's SIMD dispatch only applies to x86-64/ARM64, so 32-bit builds take the scalar path. The speaker path is bit-identical on both.

Licence

LICENSE is the upstream MIT licence, copied unchanged; kernel/ is a copy of the upstream renderer sources and keeps their notices. See THIRD_PARTY_NOTICES.md.