42 lines
2.7 KiB
Markdown
42 lines
2.7 KiB
Markdown
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# 0010 — Bounded CLAP, VST2 and VST3 effect loading
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Accepted for Phase 31. The user's request to support these three formats
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supersedes the earlier recommendation to choose only one external format.
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Keep the engine/model/host adapters in C99. CLAP uses pinned MIT headers and VST3
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uses the upstream BSD-3-Clause generated C ABI. No SDK runtime library is needed;
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Linux dynamic loading and POSIX thread identity are existing platform facilities.
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VST2 uses original minimal compatibility declarations, not the discontinued SDK.
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See third_party/README.md and LICENSES.md for exact revisions and notices.
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Reuse the existing plugin graph node, paired mono instances and immutable plan
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ownership. The common facade routes LADSPA to its existing implementation and
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modern formats to a separate adapter. This preserves LADSPA controls/automation
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and metadata behavior. All three new adapters initially accept one mono input
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and output, float32, zero reported latency and no event buses. Default plugin
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configuration is used; no parameter/controller/editor or opaque-state access is
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exposed. These are usable effect loaders, not complete implementations of every
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extension in the formats. Unsupported layouts fail explicitly.
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Project v11 adds format plus CLAP stable ID or VST3 class ID to each saved plugin.
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Older plugins migrate to LADSPA with an empty extra ID. VST2 retains its integer
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unique ID. Reopening checks format/index/identity/name/layout; metadata operations
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never open modules. This does not authenticate a binary or freeze defaults across
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plugin releases. No modified opaque state exists in this initial API to persist.
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Discovery and instance creation execute trusted module code on one serialized
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main/control thread. A module cache balances CLAP entry init/deinit and Linux
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VST3 ModuleEntry/ModuleExit across overlapping graph instances and retired plans.
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CLAP start_processing runs on the processing owner; stop_processing runs after
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quiescence with the symbolic audio-thread context. CLAP callback requests use
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lock-free flags and are serviced by xtc_plugin_idle on main/control (the GUI timer
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calls it). Restart/I/O-change requests latch an error for re-preparation; the audio
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callback does not reconfigure or wait for GUI work. CLAP process wakeups need no
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queue because playback processes every block, including silence.
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Only preallocated buffers and plugin processing occur in audio. Error status
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silences the failed block; nonfinite/subnormal samples are sanitized. Plugin code
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can still allocate, block, corrupt memory or crash; there is no sandbox, scanner
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subprocess or recoverable crash boundary. Modules unload only after destruction
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on a quiescent/control owner. Real third-party plugins and hardware timing remain
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unqualified; original ABI fixtures demonstrate the bounded contracts.
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