Windows LAV / PotPlayer

OpenJOC ships an optional downstream LAV Audio Decoder for Windows DirectShow. It has a separate filter identity and installs beside stock LAV. Installing the package does not change PotPlayer automatically.

The primary validated host workflow is PotPlayer. These instructions describe the package behavior recorded for the v0.12+ Windows integration; the OpenJOC release baseline for this site is v0.20.1.

The default audio package retains the one-click install.bat / uninstall.bat experience. Maintainers can explicitly build a separate full variant containing Audio, Video, Splitter, and QuickSync. Its manual registration changes the standard Video/Splitter registrations only when explicitly run; see full-package instructions and rollback. Downloading or extracting it does not register anything.

Install and verify

1. Download the Windows LAV package from the OpenJOC releases page.
2. Extract the complete ZIP to a writable directory.
3. Double-click install.bat and accept the Windows administrator prompt.
4. Double-click verify.bat and require PASS.
5. Close and reopen PotPlayer if it was running during installation.

The package installs under an isolated OpenJOC version directory and registers only its own DirectShow filter. It does not replace stock LAV, modify PATH, or change PowerShell execution policy.

LAV Splitter is a separate component

The OpenJOC package updates LAV Audio Decoder (OpenJOC) only; it does not update LAV Splitter / LAV Splitter Source or LAV Video. A verify.bat PASS does not verify the active splitter. Check the version and file path of the splitter actually loaded by PotPlayer separately from the audio decoder. An old splitter can misidentify PCM in MP4/MOV and cause loud static even with a current audio decoder. See PCM noise troubleshooting.

Select the filter in PotPlayer

1. Open PotPlayer preferences with F5.
2. Select Filter Control → Filter Priority (Overall).
3. Choose Add registered filter.
4. Add LAV Audio Decoder (OpenJOC).
5. Set it to Prefer, then select Apply and OK.

Keep the stock LAV decoder installed. If the OpenJOC filter is not listed, run verify.bat and repeat installation only if verification reports a failure.

Update only LAV Splitter

Use a current official x64 ZIP from the LAV Filters releases page. Version 0.83 resolved the confirmed old-splitter PCM case described in Troubleshooting; this is a known-good recommendation for that case, not a universal minimum version.

1. Stop playback, mute or lower the output volume, and close PotPlayer before changing files or registration. Keep a record of the old splitter's version and path and retain its complete package for rollback.
2. Extract the entire official x64 ZIP to a new permanent folder, separate from the OpenJOC installation and any older LAV package. Keep all bundled DLLs and manifests together. Do not copy just LAVSplitter.ax, mix DLLs between releases, or extract stock LAV over the OpenJOC audio runtime.

3. Open a native 64-bit Command Prompt as administrator and register only the new LAVSplitter.ax. In the following example, replace C:\Filters\LAVFilters-x64 with the folder you actually extracted:

   "%SystemRoot%\System32\regsvr32.exe" "C:\Filters\LAVFilters-x64\LAVSplitter.ax"
   

   Require a successful registration result. On 64-bit Windows, System32 contains the native 64-bit tool; do not use the SysWOW64 32-bit tool. This changes the system's LAV Splitter registration and can affect other DirectShow players. It does not register the stock audio or video decoder; do not run their installation scripts for this splitter-only update. See the upstream installation instructions. 4. Preserve LAV Audio Decoder (OpenJOC) as Prefer. If PotPlayer has a manually added external splitter pointing to an old file, update that entry to the new LAVSplitter.ax; system registration alone may not override it. 5. Reopen the affected file while muted. Inspect the active filter list, confirm LAV Splitter / LAV Splitter Source uses the new version and file path, and check that LAV Audio's Input format matches the source PCM as described in Troubleshooting. Only then test briefly at low volume; stop immediately if static remains.

To roll back this splitter-only change, close PotPlayer and register LAVSplitter.ax from the previous complete package, restoring any explicit PotPlayer splitter path as well. Keep each package's own dependencies together and leave the OpenJOC audio package and filter priority intact. A rollback to the affected old splitter does not fix the PCM compatibility issue.

Routing behavior

• Ordinary E-AC-3 remains on the stock LAV/FFmpeg path.
• Compressed E-AC-3 passthrough remains authoritative and bypasses OpenJOC.
• Only positively confirmed JOC is admitted to the OpenJOC filter.
• Confirmed JOC can be decoded from raw E-AC-3 and MP4 E-AC-3 input.

The Windows adapter exposes exactly eight fixed 48 kHz IEEE-float PCM policies:

Policy	Channels	WAVEFORMATEXTENSIBLE mask
Stereo (Speakers)	2	0x00000003
Binaural (Headphones)	2	0x00000003
5.1	6	0x0000060f
7.1	8	0x0000063f
5.1.2	8	0x0000560f
5.1.4	10	0x0002d60f
7.1.2	10	0x0000563f
7.1.4	12	0x0002d63f

Each policy makes one exact semantic proposal with no fallback mask. Stereo is the default; select other layouts explicitly. AUTO_NOT_RELIABLE is the current automatic downstream layout-discovery status.

OpenJOC settings

Open the filter properties and select the OpenJOC tab. OpenJOC output contains the same eight fixed output policies listed above; moving this control to its own tab does not change layout, channel-order, media-type, or Stereo default behavior.

OpenJOC output selects the PCM speaker layout that OpenJOC renders and sends to the downstream audio renderer/device. Choose a layout supported by that endpoint. Stereo (Speakers) is conventional two-speaker playback without HRTF. Binaural (Headphones) uses the built-in SADIE II D1 KU100 HRTF to render the virtual speaker field to two-channel headphone PCM. Both use the same two-channel PCM transport shape, but they are different renderers. Selecting an unsupported multichannel layout may cause playback failure, stuttering, or downstream conversion.

When Binaural is selected, the OpenJOC page also provides an HRTF source. The default is Built-in SADIE II D1 (Default). The built-in selector also offers SADIE II D2 / KEMAR; D1 remains the default. Custom SOFA... opens a normal Windows file picker for one local .sofa file; OpenJOC validates the selected dataset before Apply and uses the same strict loader as the standalone SOFA path. An invalid selection is rejected and the previous known-good HRTF remains active. If a persisted custom file is later moved, deleted, denied, or becomes invalid, reopening Binaural reports a bounded HRTF configuration error until the user selects a built-in source or another valid file.

The Binaural page also selects the virtual speaker layout: 7.1.4 (Default) or 9.1.6 (Experimental). This parameterizes the existing virtual-speaker stage before the same SOFA/HRTF backend; final output remains two-channel binaural PCM. 9.1.6 is not claimed to be better or reference quality, and its extra virtual feeds may cost more CPU.

The canonical 9.1.6 intermediate order is FL, FR, FC, LFE, Lb, Rb, Ls, Rs, Lw, Rw, Ltf, Rtf, Ltm, Rtm, Ltr, Rtr. LFE follows the existing explicit LFE policy; the other 15 virtual feeds are resolved by the existing exact or bounded interpolation path, then convolved to the two ear channels. This is a virtual layout, not a 16-channel downstream speaker output.

OpenJOC does not detect the physical speaker configuration or automatically downmix to match the endpoint. A larger layout may be rejected or accepted and converted later by Windows/the downstream renderer; that conversion is outside OpenJOC and is not equivalent to choosing Stereo (Speakers) directly.

For conventional two-speaker playback choose Stereo (Speakers); for headphones choose Binaural (Headphones).

Examples: conventional two-speaker playback → Stereo (Speakers); headphones → Binaural (Headphones); physical 5.1 → 5.1; physical 7.1 → 7.1; a height-capable endpoint → the corresponding height layout. Selecting 7.1.4 on a stereo endpoint does not provide additional OpenJOC spatialization. Any later stereo downmix, if accepted by the downstream path, happens outside OpenJOC.

Dialnorm has two choices:

• Calibrated (Recommended) respects the programme dialnorm carried by E-AC-3.
• Unity / Compatibility disables dialnorm gain for compatibility and may sound substantially louder.

This setting selects the decoder's programme-calibration policy. It is not normalization, DRC, a quality mode, or mastering gain, and it adds no post-render gain stage.

Available with the v0.19.0 LAV package: Output gain requires openjoc-lav-0.19.0-windows-x64.zip; the v0.18.0 Windows LAV package does not include it. Check that the v0.19.0 LAV asset is available on the release page before upgrading.

Output gain is an independent post-render PCM level control in the same Program Level group. It ranges from -20.0 dB to +20.0 dB, in 0.1 dB steps, and defaults to 0.0 dB. It applies the same linear gain to every channel after OpenJOC speaker or binaural rendering and before the strict PCM sample is delivered; it does not change Dialnorm, Mixing, DRC, HRTF, channel layout, frame count, or timestamps. At 0 dB the new stage is bypassed, so the existing output is unchanged. Positive gain may cause clipping; the control does not add a limiter or automatic compensation.

The Status page uses the standard LAV channel meters. It currently displays at most the first eight output channels; for 10- and 12-channel policies, the displayed first eight meters remain channel-index aligned with the PCM output. It also reports OpenJOC, Stock decoder, or Stock decoder (OpenJOC fallback). Ordinary stock AC-3/E-AC-3 has no warning. A real OpenJOC fallback displays a structured reason and bounded detail, including the first failed AU when known; the detail remains visible for that stream and clears on the next positively classified stream. Unsupported downstream output layouts are reported as output-layout errors rather than file corruption.

Passthrough and hardware boundaries

OpenJOC does not infer a layout from endpoint names, perform Bass Management, or turn multiple physical subwoofers into multiple logical LFE channels. Standalone 7.1.6, 9.1.x, 22.2, and custom geometry are not LAV output claims.

The integration proves PCM sample delivery through the documented host and endpoint checks. It does not claim physical multichannel hardware playback on arbitrary devices.

Uninstall and rollback

Double-click uninstall.bat. The package removes only OpenJOC-owned registration and files and restores the stock LAV arrangement. An already-absent OpenJOC installation is a successful no-op for the package's non-interactive uninstall path.

For the lower-level source, version pins, and engineering evidence, use the repository's LAV integration contract. Evidence files are intentionally not published in this site.