comparison vamp-hostsdk/host-c.h @ 389:93683cf9fce3 vh

Some work toward C API for plugin loading

+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    Vamp
+
+    An API for audio analysis and feature extraction plugins.
+
+    Centre for Digital Music, Queen Mary, University of London.
+    Copyright 2006-2015 Chris Cannam and QMUL.
+  
+    Permission is hereby granted, free of charge, to any person
+    obtaining a copy of this software and associated documentation
+    files (the "Software"), to deal in the Software without
+    restriction, including without limitation the rights to use, copy,
+    modify, merge, publish, distribute, sublicense, and/or sell copies
+    of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be
+    included in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
+    ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+    CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+    Except as contained in this notice, the names of the Centre for
+    Digital Music; Queen Mary, University of London; and Chris Cannam
+    shall not be used in advertising or otherwise to promote the sale,
+    use or other dealings in this Software without prior written
+    authorization.
+*/
+
+/*
+    This file defines a low-level API for enumerating and loading
+    plugin libraries using C calling conventions. It could be used in
+    C programs or in languages with C-compatible foreign-function
+    interfaces.
+
+    This is not the simplest or easiest interface for hosting Vamp
+    plugins -- if you have the capability to use the C++ API, please
+    do that instead. (Most programs should not even include this
+    header.)
+
+    The C and C++ interfaces provide different abstraction levels:
+
+    In the C++ interface, the class PluginLoader provides a list of
+    keys corresponding to the installed plugins (where a key combines
+    the plugin's library name and plugin identifier into a single
+    string) plus a method to load a single plugin based on its key
+    (obtaining an instance of class Plugin). With the C++ interface
+    you go straight from the key to a live instance of the plugin. The
+    PluginLoader also provides various facilities to adapt the plugin
+    based on your requirements (e.g. to do time- to frequency-domain
+    conversion for its input).
+
+    This low-level C interface, on the other hand, deals only in
+    plugin libraries and static descriptors, not in plugin
+    instances. You can enumerate the installed libraries, getting just
+    the base .soname of each library. Then you can retrieve each of
+    the raw C plugin descriptors from a library, and use the
+    descriptor (whose interface is defined in vamp/vamp.h) to
+    instantiate the plugin. So this header corresponds to the first
+    part of the PluginLoader class interface (finding and loading
+    plugin libraries and retrieving plugin descriptors from them) but
+    does not do any of the rest (instantiating and adapting the
+    plugins themselves), which may mean the resulting plugin is
+    relatively hard to use compared to that provided by the
+    PluginLoader API.
+
+    This API is not thread-safe; use it from a single application
+    thread, or guard access to it with a mutex.
+
+    This header was introduced in version 2.6 of the Vamp plugin SDK.
+*/
+
+#ifndef VAMPHOST_C_H_INCLUDED
+#define VAMPHOST_C_H_INCLUDED
+
+#include <vamp/vamp.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct vhLibrary_t *vhLibrary;
+
+/**
+ * Return the number of Vamp plugin libraries discovered in the
+ * installation path. This number will remain fixed after the first
+ * call -- plugins are only discovered once, the first time this
+ * function is called.
+ */
+extern int vhGetLibraryCount();
+
+/**
+ * Return the library name (base soname) of the library with the given
+ * index, in the range 0..(vhGetLibraryCount()-1).
+ */
+extern const char *vhGetLibraryName(int library);
+
+/**
+ * Load a plugin library given its library name, that is, the base
+ * soname as returned by vhGetLibraryName. If the library cannot be
+ * loaded for any reason, the return value is 0; otherwise it is an
+ * opaque pointer suitable for passing to other functions in this API.
+ */
+extern vhLibrary vhLoadLibrary(const char *libraryName);
+
+/**
+ * Return the number of Vamp plugins in the given library.
+ */
+extern int vhGetPluginCount(vhLibrary library);
+
+/**
+ * Return a Vamp plugin descriptor for a plugin in a given
+ * library. (This simply calls the vampGetPluginDescriptor function in
+ * that library with the given plugin index and returns the result.)
+ */ 
+extern const VampPluginDescriptor *vhGetPluginDescriptor(vhLibrary library,
+							 int plugin);
+
+/**
+ * Unload a plugin library. Do not do this while any of its plugins
+ * are still in use.
+ */
+extern void vhUnloadLibrary(vhLibrary);
+    
+#ifdef __cplusplus
+}
+#endif
+
+#endif