Move Codec2-related code from hardware/google/av

Test: None
Bug: 112362730
Change-Id: Ie2f8ff431d65c40333f267ab9877d47089adeea4
diff --git a/media/codec2/include/C2Component.h b/media/codec2/include/C2Component.h
new file mode 100644
index 0000000..8810725
--- /dev/null
+++ b/media/codec2/include/C2Component.h
@@ -0,0 +1,975 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef C2COMPONENT_H_
+
+#define C2COMPONENT_H_
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <list>
+#include <memory>
+#include <vector>
+#include <functional>
+
+#include <C2Enum.h>
+#include <C2Param.h>
+#include <C2Work.h>
+
+/// \defgroup components Components
+/// @{
+
+struct C2FieldSupportedValuesQuery {
+    enum type_t : uint32_t {
+        POSSIBLE, ///< query all possible values regardless of other settings
+        CURRENT,  ///< query currently possible values given dependent settings
+    };
+
+private:
+    C2ParamField _mField;
+    type_t _mType;
+public:
+    c2_status_t status;
+    C2FieldSupportedValues values;
+
+    C2FieldSupportedValuesQuery(const C2ParamField &field_, type_t type_)
+        : _mField(field_), _mType(type_), status(C2_NO_INIT) { }
+
+    static C2FieldSupportedValuesQuery
+    Current(const C2ParamField &field_) {
+        return C2FieldSupportedValuesQuery(field_, CURRENT);
+    }
+
+    static C2FieldSupportedValuesQuery
+    Possible(const C2ParamField &field_) {
+        return C2FieldSupportedValuesQuery(field_, POSSIBLE);
+    }
+
+    inline C2ParamField field() const { return _mField; };
+
+    inline type_t type() const { return _mType; }
+};
+
+/**
+ * Component interface object. This object contains all of the configuration of a potential or
+ * actual component. It can be created and used independently of an actual C2Component instance to
+ * query support and parameters for various component settings and configurations for a potential
+ * component. Actual components also expose this interface.
+ */
+
+class C2ComponentInterface {
+public:
+    // ALWAYS AVAILABLE METHODS
+    // =============================================================================================
+
+    /**
+     * Returns the name of this component or component interface object.
+     * This is a unique name for this component or component interface 'class'; however, multiple
+     * instances of this component SHALL have the same name.
+     *
+     * When attached to a component, this method MUST be supported in any component state.
+     * This call does not change the state nor the internal configuration of the component.
+     *
+     * This method MUST be "non-blocking" and return within 1ms.
+     *
+     * \return the name of this component or component interface object.
+     * \retval an empty string if there was not enough memory to allocate the actual name.
+     */
+    virtual C2String getName() const = 0;
+
+    /**
+     * Returns a unique ID for this component or interface object.
+     * This ID is used as work targets, unique work IDs, and when configuring tunneling.
+     *
+     * When attached to a component, this method MUST be supported in any component state.
+     * This call does not change the state nor the internal configuration of the component.
+     *
+     * This method MUST be "non-blocking" and return within 1ms.
+     *
+     * \return a unique node ID for this component or component interface instance.
+     */
+    virtual c2_node_id_t getId() const = 0;
+
+    /**
+     * Queries a set of parameters from the component or interface object.
+     * Querying is performed at best effort: the component SHALL query all supported parameters and
+     * skip unsupported ones, heap allocated parameters that could not be allocated or parameters
+     * that could not be queried without blocking. Any errors are communicated in the return value.
+     * Additionally, preallocated (e.g. stack) parameters that could not be queried are invalidated.
+     * Invalid or blocking parameters to be allocated on the heap are omitted from the result.
+     *
+     * \note Parameter values do not depend on the order of query.
+     *
+     * \todo This method cannot be used to query info-buffers. Is that a problem?
+     *
+     * When attached to a component, this method MUST be supported in any component state except
+     * released.
+     * This call does not change the state nor the internal configuration of the component.
+     *
+     * This method has a variable blocking behavior based on state.
+     * In the stopped state this method MUST be "non-blocking" and return within 1ms.
+     * In the running states this method may be momentarily blocking, but MUST return within 5ms.
+     *
+     * \param[in,out] stackParams  a list of params queried. These are initialized specific to each
+     *                             setting; e.g. size and index are set and rest of the members are
+     *                             cleared.
+     *                             \note Flexible settings that are of incorrect size will be
+     *                             invalidated.
+     * \param[in] heapParamIndices a vector of param indices for params to be queried and returned
+     *                             on the heap. These parameters will be returned in heapParams.
+     *                             Unsupported param indices will be ignored.
+     * \param[in] mayBlock         if true (C2_MAY_BLOCK), implementation may momentarily block.
+     *                             Otherwise (C2_DONT_BLOCK), it must be "non-blocking".
+     * \param[out] heapParams      a list of params where to which the supported heap parameters
+     *                             will be appended in the order they appear in heapParamIndices.
+     *
+     * \retval C2_OK        all parameters could be queried
+     * \retval C2_BAD_INDEX all supported parameters could be queried, but some parameters were not
+     *                      supported
+     * \retval C2_BAD_STATE when called in the released component state (user error)
+     *                      (this error code is only allowed for interfaces connected to components)
+     * \retval C2_NO_MEMORY could not allocate memory for a supported parameter
+     * \retval C2_BLOCKING  the operation must block to complete but mayBlock is false
+     *                      (this error code is only allowed for interfaces connected to components)
+     * \retval C2_TIMED_OUT could not query the parameters within the time limit (unexpected)
+     *                      (this error code is only allowed for interfaces connected to components
+     *                      in the running state)
+     * \retval C2_CORRUPTED some unknown error prevented the querying of the parameters
+     *                      (unexpected)
+     *                      (this error code is only allowed for interfaces connected to components)
+     */
+    virtual c2_status_t query_vb(
+        const std::vector<C2Param*> &stackParams,
+        const std::vector<C2Param::Index> &heapParamIndices,
+        c2_blocking_t mayBlock,
+        std::vector<std::unique_ptr<C2Param>>* const heapParams) const = 0;
+
+    /**
+     * Sets a set of parameters for the component or interface object.
+     *
+     * Tuning is performed at best effort: the component SHALL process the configuration updates in
+     * the order they appear in |params|. If any parameter update fails, the component shall
+     * communicate the failure in the return value and in |failures|, and still process the
+     * remaining parameters. Unsupported parameters are skipped, though they are communicated in
+     * ther return value. Most parameters are updated at best effort - such that even if client
+     * specifies an unsupported value for a field, the closest supported value is used. On the
+     * other hand, strict parameters only accept specific values for their fields, and if the client
+     * specifies an unsupported value, the parameter setting shall fail for that field.
+     * If the client tries to change the value of a field that requires momentary blocking without
+     * setting |mayBlock| to C2_MAY_BLOCK, that parameter shall also be skipped and a specific
+     * return value shall be used. Final values for all parameters set are propagated back to the
+     * caller in |params|.
+     *
+     * \note Parameter tuning DOES depend on the order of the tuning parameters. E.g. some parameter
+     * update may allow some subsequent values for further parameter updates.
+     *
+     * When attached to a component, this method MUST be supported in any component state except
+     * released.
+     *
+     * This method has a variable blocking behavior based on state.
+     * In the stopped state this method MUST be "non-blocking" and return within 1ms.
+     * In the running states this method may be momentarily blocking, but MUST return within 5ms.
+     *
+     * \param[in,out] params a list of parameter updates. These will be updated to the actual
+     *                       parameter values after the updates (this is because tuning is performed
+     *                       at best effort).
+     *                       \todo params that could not be updated are not marked here, so are
+     *                       confusing - are they "existing" values or intended to be configured
+     *                       values?
+     * \param[in] mayBlock   if true (C2_MAY_BLOCK), implementation may momentarily block.
+     *                       Otherwise (C2_DONT_BLOCK), it must be "non-blocking".
+     * \param[out] failures  a list of parameter failures and optional guidance
+     *
+     * \retval C2_OK        all parameters could be updated successfully
+     * \retval C2_BAD_INDEX all supported parameters could be updated successfully, but some
+     *                      parameters were not supported
+     * \retval C2_BAD_VALUE some supported parameters could not be updated successfully because
+     *                      they contained unsupported values. These are returned in |failures|.
+     * \retval C2_BAD_STATE when called in the released component state (user error)
+     *                      (this error code is only allowed for interfaces connected to components)
+     * \retval C2_NO_MEMORY some supported parameters could not be updated successfully because
+     *                      they contained unsupported values, but could not allocate a failure
+     *                      object for them.
+     * \retval C2_TIMED_OUT could not set the parameters within the time limit (unexpected)
+     *                      (this error code is only allowed for interfaces connected to components
+     *                      in the running state)
+     * \retval C2_BLOCKING  the operation must block to complete but mayBlock is false
+     *                      (this error code is only allowed for interfaces connected to components)
+     * \retval C2_CORRUPTED some unknown error prevented the update of the parameters
+     *                      (unexpected)
+     *                      (this error code is only allowed for interfaces connected to components)
+     */
+    virtual c2_status_t config_vb(
+            const std::vector<C2Param*> &params,
+            c2_blocking_t mayBlock,
+            std::vector<std::unique_ptr<C2SettingResult>>* const failures) = 0;
+
+    // TUNNELING
+    // =============================================================================================
+
+    /**
+     * Creates a tunnel from this component to the target component.
+     *
+     * If the component is successfully created, subsequent work items queued may include a
+     * tunneled path between these components.
+     *
+     * When attached to a component, this method MUST be supported in any component state except
+     * released.
+     *
+     * This method may be momentarily blocking, but MUST return within 5ms.
+     *
+     * \retval C2_OK        the tunnel was successfully created
+     * \retval C2_BAD_INDEX the target component does not exist
+     * \retval C2_DUPLICATE the tunnel already exists
+     * \retval C2_OMITTED   tunneling is not supported by this component
+     * \retval C2_CANNOT_DO the specific tunnel is not supported
+     * \retval C2_BAD_STATE when called in the released component state (user error)
+     *                      (this error code is only allowed for interfaces connected to components)
+     *
+     * \retval C2_TIMED_OUT could not create the tunnel within the time limit (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented the creation of the tunnel (unexpected)
+     *                      (this error code is only allowed for interfaces connected to components)
+     */
+    virtual c2_status_t createTunnel_sm(c2_node_id_t targetComponent) = 0;
+
+    /**
+     * Releases a tunnel from this component to the target component.
+     *
+     * The release of a tunnel is delayed while there are pending work items for the tunnel.
+     * After releasing a tunnel, subsequent work items queued MUST NOT include a tunneled
+     * path between these components.
+     *
+     * When attached to a component, this method MUST be supported in any component state except
+     * released.
+     *
+     * This method may be momentarily blocking, but MUST return within 5ms.
+     *
+     * \retval C2_OK        the tunnel was marked for release successfully
+     * \retval C2_BAD_INDEX the target component does not exist
+     * \retval C2_NOT_FOUND the tunnel does not exist
+     * \retval C2_OMITTED   tunneling is not supported by this component
+     * \retval C2_BAD_STATE when called in the released component state (user error)
+     *                      (this error code is only allowed for interfaces connected to components)
+     *
+     * \retval C2_TIMED_OUT could not mark the tunnel for release within the time limit (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented the release of the tunnel (unexpected)
+     *                      (this error code is only allowed for interfaces connected to components)
+     */
+    virtual c2_status_t releaseTunnel_sm(c2_node_id_t targetComponent) = 0;
+
+    // REFLECTION MECHANISM (USED FOR EXTENSION)
+    // =============================================================================================
+
+    /**
+     * Returns the set of supported parameters.
+     *
+     * When attached to a component, this method MUST be supported in any component state except
+     * released.
+     *
+     * This method MUST be "non-blocking" and return within 1ms.
+     *
+     * \param[out] params a vector of supported parameters will be appended to this vector.
+     *
+     * \retval C2_OK        the operation completed successfully.
+     * \retval C2_BAD_STATE when called in the released component state (user error)
+     *                      (this error code is only allowed for interfaces connected to components)
+     * \retval C2_NO_MEMORY not enough memory to complete this method.
+     */
+    virtual c2_status_t querySupportedParams_nb(
+            std::vector<std::shared_ptr<C2ParamDescriptor>> * const params) const = 0;
+
+    /**
+     * Retrieves the supported values for the queried fields.
+     *
+     * Client SHALL set the parameter-field specifier and the type of supported values query (e.g.
+     * currently supported values, or potential supported values) in fields.
+     * Upon return the component SHALL fill in the supported values for the fields listed as well
+     * as a status for each field. Component shall process all fields queried even if some queries
+     * fail.
+     *
+     * When attached to a component, this method MUST be supported in any component state except
+     * released.
+     *
+     * This method has a variable blocking behavior based on state.
+     * In the stopped state this method MUST be "non-blocking" and return within 1ms.
+     * In the running states this method may be momentarily blocking, but MUST return within 5ms.
+     *
+     * \param[in out] fields a vector of fields descriptor structures.
+     * \param[in] mayBlock   if true (C2_MAY_BLOCK), implementation may momentarily block.
+     *                       Otherwise (C2_DONT_BLOCK), it must be "non-blocking".
+     *
+     * \retval C2_OK        the operation completed successfully.
+     * \retval C2_BAD_STATE when called in the released component state (user error)
+     *                      (this error code is only allowed for interfaces connected to components)
+     * \retval C2_BAD_INDEX at least one field was not recognized as a component field
+     * \retval C2_TIMED_OUT could not query supported values within the time limit (unexpected)
+     *                      (this error code is only allowed for interfaces connected to components
+     *                      in the running state)
+     * \retval C2_BLOCKING  the operation must block to complete but mayBlock is false
+     *                      (this error code is only allowed for interfaces connected to components)
+     * \retval C2_CORRUPTED some unknown error prevented the operation from completing (unexpected)
+     *                      (this error code is only allowed for interfaces connected to components)
+     */
+    virtual c2_status_t querySupportedValues_vb(
+            std::vector<C2FieldSupportedValuesQuery> &fields, c2_blocking_t mayBlock) const = 0;
+
+    virtual ~C2ComponentInterface() = default;
+};
+
+class C2Component {
+public:
+    class Listener {
+    public:
+        virtual void onWorkDone_nb(std::weak_ptr<C2Component> component,
+                                std::list<std::unique_ptr<C2Work>> workItems) = 0;
+
+        virtual void onTripped_nb(std::weak_ptr<C2Component> component,
+                               std::vector<std::shared_ptr<C2SettingResult>> settingResult) = 0;
+
+        virtual void onError_nb(std::weak_ptr<C2Component> component,
+                             uint32_t errorCode) = 0;
+
+        // virtual void onTunnelReleased(<from>, <to>) = 0;
+
+        // virtual void onComponentReleased(<id>) = 0;
+
+        virtual ~Listener() = default;
+    };
+
+    /**
+     * Sets the listener for this component
+     *
+     * This method MUST be supported in all states except released.
+     * The listener can only be set to non-null value in stopped state (that does not include
+     * tripped or error). It can be set to nullptr in both stopped and running states.
+     * Components only use the listener in running state.
+     *
+     * If listener is nullptr, the component SHALL guarantee that no more listener callbacks are
+     * done to the original listener once this method returns. (Any pending listener callbacks will
+     * need to be completed during this call - hence this call may be temporarily blocking.)
+     *
+     * This method has a variable blocking behavior based on state.
+     * In the stopped state this method MUST be "non-blocking" and return within 1ms.
+     * In the running states this method may be momentarily blocking, but MUST return within 5ms.
+     *
+     * Component SHALL handle listener notifications from the same thread (the thread used is
+     * at the component's discretion.)
+     *
+     * \note This could also be accomplished by passing a weak_ptr to a component-specific listener
+     * here and requiring the client to always promote the weak_ptr before any callback. This would
+     * put the burden on the client to clear the listener - wait for its deletion - at which point
+     * it is guaranteed that no more listener callbacks will occur.
+     *
+     * \param[in] listener the component listener object
+     * \param[in] mayBlock if true (C2_MAY_BLOCK), implementation may momentarily block.
+     *                     Otherwise (C2_DONT_BLOCK), it must be "non-blocking".
+     *
+     * \retval C2_BAD_STATE attempting to change the listener in the running state to a non-null
+     *                      value (user error), or called in the released state
+     * \retval C2_BLOCKING  the operation must block to complete but mayBlock is false
+     * \retval C2_OK        listener was updated successfully.
+     */
+    virtual c2_status_t setListener_vb(
+            const std::shared_ptr<Listener> &listener, c2_blocking_t mayBlock) = 0;
+
+    /// component domain (e.g. audio or video)
+    enum domain_t : uint32_t;
+
+    /// component kind (e.g. encoder, decoder or filter)
+    enum kind_t : uint32_t;
+
+    /// component rank. This number is used to determine component ordering (the lower the sooner)
+    /// in the component list.
+    typedef uint32_t rank_t;
+
+    /// component attributes
+    enum attrib_t : uint64_t;
+
+    /**
+     * Information about a component.
+     */
+    struct Traits {
+    // public:
+        C2String name; ///< name of the component
+        domain_t domain; ///< component domain
+        kind_t kind; ///< component kind
+        rank_t rank; ///< component rank
+        C2String mediaType; ///< media type supported by the component
+
+        /**
+         * name alias(es) for backward compatibility.
+         * \note Multiple components can have the same alias as long as their media-type differs.
+         */
+        std::vector<C2StringLiteral> aliases; ///< name aliases for backward compatibility
+    };
+
+    // METHODS AVAILABLE WHEN RUNNING
+    // =============================================================================================
+
+    /**
+     * Queues up work for the component.
+     *
+     * This method MUST be supported in running (including tripped and error) states.
+     *
+     * This method MUST be "non-blocking" and return within 1 ms
+     *
+     * It is acceptable for this method to return OK and return an error value using the
+     * onWorkDone() callback.
+     *
+     * \retval C2_OK        the work was successfully queued
+     * \retval C2_BAD_INDEX some component(s) in the work do(es) not exist
+     * \retval C2_CANNOT_DO the components are not tunneled
+     * \retval C2_BAD_STATE when called in the stopped or released state (user error)
+     *
+     * \retval C2_NO_MEMORY not enough memory to queue the work
+     * \retval C2_CORRUPTED some unknown error prevented queuing the work (unexpected)
+     */
+    virtual c2_status_t queue_nb(std::list<std::unique_ptr<C2Work>>* const items) = 0;
+
+    /**
+     * Announces a work to be queued later for the component. This reserves a slot for the queue
+     * to ensure correct work ordering even if the work is queued later.
+     *
+     * This method MUST be supported in running (including tripped and error) states.
+     *
+     * This method MUST be "non-blocking" and return within 1 ms
+     *
+     * \retval C2_OK        the work announcement has been successfully recorded
+     * \retval C2_BAD_INDEX some component(s) in the work outline do(es) not exist
+     * \retval C2_CANNOT_DO the componentes are not tunneled
+     * \retval C2_BAD_STATE when called in the stopped or released state (user error)
+     *
+     * \retval C2_NO_MEMORY not enough memory to record the work announcement
+     * \retval C2_CORRUPTED some unknown error prevented recording the announcement (unexpected)
+     *
+     * \todo Can this be rolled into queue_nb?
+     * \todo Expose next work item for each component to detect stalls
+     */
+    virtual c2_status_t announce_nb(const std::vector<C2WorkOutline> &items) = 0;
+
+    enum flush_mode_t : uint32_t {
+        /// flush work from this component only
+        FLUSH_COMPONENT,
+
+        /// flush work from this component and all components connected downstream from it via
+        /// tunneling
+        FLUSH_CHAIN = (1 << 16),
+    };
+
+    /**
+     * Discards and abandons any pending work for the component, and optionally any component
+     * downstream.
+     *
+     * \todo define this: we could flush all work before last item queued for component across all
+     *                    components linked to this; flush only work items that are queued to this
+     *                    component
+     * \todo return work # of last flushed item; or all flushed (but not returned items)
+     * \todo we could make flush take a work item and flush all work before/after that item to allow
+     *       TBD (slicing/seek?)
+     * \todo we could simply take a list of numbers and flush those... this is bad for decoders
+     *       also, what would happen to fine grade references?
+     *
+     * This method MUST be supported in running (including tripped and error) states.
+     *
+     * This method may be momentarily blocking, but must return within 5ms.
+     *
+     * Work that could be immediately abandoned/discarded SHALL be returned in |flushedWork|; this
+     * can be done in an arbitrary order.
+     *
+     * Work that could not be abandoned or discarded immediately SHALL be marked to be
+     * discarded at the earliest opportunity, and SHALL be returned via the onWorkDone() callback.
+     * This shall be completed within 500ms.
+     *
+     * \param mode flush mode
+     *
+     * \retval C2_OK        the component has been successfully flushed
+     * \retval C2_BAD_STATE when called in the stopped or released state (user error)
+     * \retval C2_TIMED_OUT the flush could not be completed within the time limit (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented flushing from completion (unexpected)
+     */
+    virtual c2_status_t flush_sm(flush_mode_t mode, std::list<std::unique_ptr<C2Work>>* const flushedWork) = 0;
+
+    enum drain_mode_t : uint32_t {
+        /// drain component only and add an "end-of-stream" marker. Component shall process all
+        /// queued work and complete the current stream. If new input is received, it shall start
+        /// a new stream. \todo define what a stream is.
+        DRAIN_COMPONENT_WITH_EOS,
+        /// drain component without setting "end-of-stream" marker. Component shall process all
+        /// queued work but shall expect more work items for the same stream.
+        DRAIN_COMPONENT_NO_EOS = (1 << 0),
+
+        /// marks the last work item with a persistent "end-of-stream" marker that will drain
+        /// downstream components
+        /// \todo this may confuse work-ordering downstream
+        DRAIN_CHAIN = (1 << 16),
+
+        /**
+         * \todo define this; we could place EOS to all upstream components, just this component, or
+         *       all upstream and downstream component.
+         * \todo should EOS carry over to downstream components?
+         */
+    };
+
+    /**
+     * Drains the component, and optionally downstream components. This is a signalling method;
+     * as such it does not wait for any work completion.
+     *
+     * Marks last work item as "drain-till-here", so component is notified not to wait for further
+     * work before it processes work already queued. This method can also used to set the
+     * end-of-stream flag after work has been queued. Client can continue to queue further work
+     * immediately after this method returns.
+     *
+     * This method MUST be supported in running (including tripped) states.
+     *
+     * This method MUST be "non-blocking" and return within 1ms.
+     *
+     * Work that is completed SHALL be returned via the onWorkDone() callback.
+     *
+     * \param mode drain mode
+     *
+     * \retval C2_OK        the drain request has been successfully recorded
+     * \retval C2_BAD_STATE when called in the stopped or released state (user error)
+     * \retval C2_BAD_VALUE the drain mode is not supported by the component
+     *                      \todo define supported modes discovery
+     * \retval C2_TIMED_OUT the flush could not be completed within the time limit (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented flushing from completion (unexpected)
+     */
+    virtual c2_status_t drain_nb(drain_mode_t mode) = 0;
+
+    // STATE CHANGE METHODS
+    // =============================================================================================
+
+    /**
+     * Starts the component.
+     *
+     * This method MUST be supported in stopped state, as well as during the tripped state.
+     *
+     * If the return value is C2_OK, the component shall be in the running state.
+     * If the return value is C2_BAD_STATE or C2_DUPLICATE, no state change is expected as a
+     * response to this call.
+     * Otherwise, the component shall be in the stopped state.
+     *
+     * \note If a component is in the tripped state and start() is called while the component
+     * configuration still results in a trip, start shall succeed and a new onTripped callback
+     * should be used to communicate the configuration conflict that results in the new trip.
+     *
+     * \todo This method MUST return within 500ms. Seems this should be able to return quickly, as
+     * there are no immediate guarantees. Though there are guarantees for responsiveness immediately
+     * after start returns.
+     *
+     * \retval C2_OK        the component has started (or resumed) successfully
+     * \retval C2_DUPLICATE when called during another start call from another thread
+     * \retval C2_BAD_STATE when called in any state other than the stopped state or tripped state,
+     *                      including when called during another state change call from another
+     *                      thread (user error)
+     * \retval C2_NO_MEMORY not enough memory to start the component
+     * \retval C2_TIMED_OUT the component could not be started within the time limit (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented starting the component (unexpected)
+     */
+    virtual c2_status_t start() = 0;
+
+    /**
+     * Stops the component.
+     *
+     * This method MUST be supported in running (including tripped) state.
+     *
+     * This method MUST return withing 500ms.
+     *
+     * Upon this call, all pending work SHALL be abandoned and all buffer references SHALL be
+     * released.
+     * If the return value is C2_BAD_STATE or C2_DUPLICATE, no state change is expected as a
+     * response to this call.
+     * For all other return values, the component shall be in the stopped state.
+     *
+     * \todo should this return completed work, since client will just free it? Perhaps just to
+     * verify accounting.
+     *
+     * This does not alter any settings and tunings that may have resulted in a tripped state.
+     * (Is this material given the definition? Perhaps in case we want to start again.)
+     *
+     * \retval C2_OK        the component has started successfully
+     * \retval C2_DUPLICATE when called during another stop call from another thread
+     * \retval C2_BAD_STATE when called in any state other than the running state, including when
+     *                      called during another state change call from another thread (user error)
+     * \retval C2_TIMED_OUT the component could not be stopped within the time limit (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented stopping the component (unexpected)
+     */
+    virtual c2_status_t stop() = 0;
+
+    /**
+     * Resets the component.
+     *
+     * This method MUST be supported in all (including tripped) states other than released.
+     *
+     * This method MUST be supported during any other blocking call.
+     *
+     * This method MUST return withing 500ms.
+     *
+     * After this call returns all work SHALL be abandoned, all buffer references SHALL be released.
+     * If the return value is C2_BAD_STATE or C2_DUPLICATE, no state change is expected as a
+     * response to this call.
+     * For all other return values, the component shall be in the stopped state.
+     *
+     * \todo should this return completed work, since client will just free it? Also, if it unblocks
+     * a stop, where should completed work be returned?
+     *
+     * This brings settings back to their default - "guaranteeing" no tripped space.
+     *
+     * \todo reclaim support - it seems that since ownership is passed, this will allow reclaiming
+     * stuff.
+     *
+     * \retval C2_OK        the component has been reset
+     * \retval C2_DUPLICATE when called during another reset call from another thread
+     * \retval C2_BAD_STATE when called in the released state
+     * \retval C2_TIMED_OUT the component could not be reset within the time limit (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented resetting the component (unexpected)
+     */
+    virtual c2_status_t reset() = 0;
+
+    /**
+     * Releases the component.
+     *
+     * This method MUST be supported in stopped state.
+     *
+     * This method MUST return withing 500ms. Upon return all references shall be abandoned.
+     *
+     * \retval C2_OK        the component has been released
+     * \retval C2_DUPLICATE the component is already released
+     * \retval C2_BAD_STATE the component is running
+     * \retval C2_TIMED_OUT the component could not be released within the time limit (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented releasing the component (unexpected)
+     */
+    virtual c2_status_t release() = 0;
+
+    /**
+     * Returns the interface for this component.
+     *
+     * \return the component interface
+     */
+    virtual std::shared_ptr<C2ComponentInterface> intf() = 0;
+
+    virtual ~C2Component() = default;
+};
+
+C2ENUM(C2Component::kind_t, uint32_t,
+    KIND_OTHER,
+    KIND_DECODER,
+    KIND_ENCODER
+);
+
+C2ENUM(C2Component::domain_t, uint32_t,
+    DOMAIN_OTHER,
+    DOMAIN_VIDEO,
+    DOMAIN_AUDIO,
+    DOMAIN_IMAGE
+);
+
+class C2FrameInfoParser {
+public:
+    /**
+     * \return the content type supported by this info parser.
+     *
+     * \todo this may be redundant
+     */
+    virtual C2StringLiteral getType() const = 0;
+
+    /**
+     * \return a vector of supported parameter indices parsed by this info parser.
+     *
+     * This method MUST be "non-blocking" and return within 1ms.
+     *
+     * \todo sticky vs. non-sticky params? this may be communicated by param-reflector.
+     */
+    virtual const std::vector<C2Param::Index> getParsedParams() const = 0;
+
+    /**
+     * Resets this info parser. This brings this parser to its initial state after creation.
+     *
+     * This method SHALL return within 5ms.
+     *
+     * \retval C2_OK        the info parser was reset
+     * \retval C2_TIMED_OUT could not reset the parser within the time limit (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented the resetting of the parser (unexpected)
+     */
+    virtual c2_status_t reset() { return C2_OK; }
+
+    virtual c2_status_t parseFrame(C2FrameData &frame);
+
+    virtual ~C2FrameInfoParser() = default;
+};
+
+class C2AllocatorStore {
+public:
+    typedef C2Allocator::id_t id_t;
+
+    enum : C2Allocator::id_t {
+        DEFAULT_LINEAR,     ///< basic linear allocator type
+        DEFAULT_GRAPHIC,    ///< basic graphic allocator type
+        PLATFORM_START = 0x10,
+        VENDOR_START   = 0x100,
+        BAD_ID         = C2Allocator::BAD_ID, ///< DO NOT USE
+    };
+
+    /**
+     * Returns the unique name of this allocator store.
+     *
+     * This method MUST be "non-blocking" and return within 1ms.
+     *
+     * \return the name of this allocator store.
+     * \retval an empty string if there was not enough memory to allocate the actual name.
+     */
+    virtual C2String getName() const = 0;
+
+    /**
+     * Returns the set of allocators supported by this allocator store.
+     *
+     * This method MUST be "non-blocking" and return within 1ms.
+     *
+     * \retval vector of allocator information (as shared pointers)
+     * \retval an empty vector if there was not enough memory to allocate the whole vector.
+     */
+    virtual std::vector<std::shared_ptr<const C2Allocator::Traits>> listAllocators_nb() const = 0;
+
+    /**
+     * Retrieves/creates a shared allocator object.
+     *
+     * This method MUST be return within 5ms.
+     *
+     * The allocator is created on first use, and the same allocator is returned on subsequent
+     * concurrent uses in the same process. The allocator is freed when it is no longer referenced.
+     *
+     * \param id      the ID of the allocator to create. This is defined by the store, but
+     *                the ID of the default linear and graphic allocators is formalized.
+     * \param allocator shared pointer where the created allocator is stored. Cleared on failure
+     *                  and updated on success.
+     *
+     * \retval C2_OK        the allocator was created successfully
+     * \retval C2_TIMED_OUT could not create the allocator within the time limit (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented the creation of the allocator (unexpected)
+     *
+     * \retval C2_NOT_FOUND no such allocator
+     * \retval C2_NO_MEMORY not enough memory to create the allocator
+     */
+    virtual c2_status_t fetchAllocator(id_t id, std::shared_ptr<C2Allocator>* const allocator) = 0;
+
+    virtual ~C2AllocatorStore() = default;
+};
+
+class C2ComponentStore {
+public:
+    /**
+     * Returns the name of this component or component interface object.
+     * This is a unique name for this component or component interface 'class'; however, multiple
+     * instances of this component SHALL have the same name.
+     *
+     * This method MUST be supported in any state. This call does not change the state nor the
+     * internal states of the component.
+     *
+     * This method MUST be "non-blocking" and return within 1ms.
+     *
+     * \return the name of this component or component interface object.
+     * \retval an empty string if there was not enough memory to allocate the actual name.
+     */
+    virtual C2String getName() const = 0;
+
+    /**
+     * Creates a component.
+     *
+     * This method SHALL return within 100ms.
+     *
+     * \param name          name of the component to create
+     * \param component     shared pointer where the created component is stored. Cleared on
+     *                      failure and updated on success.
+     *
+     * \retval C2_OK        the component was created successfully
+     * \retval C2_TIMED_OUT could not create the component within the time limit (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented the creation of the component (unexpected)
+     *
+     * \retval C2_NOT_FOUND no such component
+     * \retval C2_NO_MEMORY not enough memory to create the component
+     */
+    virtual c2_status_t createComponent(
+            C2String name, std::shared_ptr<C2Component>* const component) = 0;
+
+    /**
+     * Creates a component interface.
+     *
+     * This method SHALL return within 100ms.
+     *
+     * \param name          name of the component interface to create
+     * \param interface     shared pointer where the created interface is stored
+     *
+     * \retval C2_OK        the component interface was created successfully
+     * \retval C2_TIMED_OUT could not create the component interface within the time limit
+     *                      (unexpected)
+     * \retval C2_CORRUPTED some unknown error prevented the creation of the component interface
+     *                      (unexpected)
+     *
+     * \retval C2_NOT_FOUND no such component interface
+     * \retval C2_NO_MEMORY not enough memory to create the component interface
+     *
+     * \todo Do we need an interface, or could this just be a component that is never started?
+     */
+    virtual c2_status_t createInterface(
+            C2String name, std::shared_ptr<C2ComponentInterface>* const interface) = 0;
+
+    /**
+     * Returns the list of components supported by this component store.
+     *
+     * This method MUST return within 500ms.
+     *
+     * \retval vector of component information.
+     */
+    virtual std::vector<std::shared_ptr<const C2Component::Traits>> listComponents() = 0;
+
+    // -------------------------------------- UTILITY METHODS --------------------------------------
+
+    // on-demand buffer layout conversion (swizzling)
+    //
+    virtual c2_status_t copyBuffer(
+            std::shared_ptr<C2GraphicBuffer> src, std::shared_ptr<C2GraphicBuffer> dst) = 0;
+
+    // -------------------------------------- CONFIGURATION API -----------------------------------
+    // e.g. for global settings (system-wide stride, etc.)
+
+    /**
+     * Queries a set of system-wide parameters.
+     * Querying is performed at best effort: the store SHALL query all supported parameters and
+     * skip unsupported ones, or heap allocated parameters that could not be allocated. Any errors
+     * are communicated in the return value. Additionally, preallocated (e.g. stack) parameters that
+     * could not be queried are invalidated. Parameters to be allocated on the heap are omitted from
+     * the result.
+     *
+     * \note Parameter values do not depend on the order of query.
+     *
+     * This method may be momentarily blocking, but MUST return within 5ms.
+     *
+     * \param stackParams   a list of params queried. These are initialized specific to each
+     *                      setting; e.g. size and index are set and rest of the members are
+     *                      cleared.
+     *                      NOTE: Flexible settings that are of incorrect size will be invalidated.
+     * \param heapParamIndices a vector of param indices for params to be queried and returned on the
+     *                      heap. These parameters will be returned in heapParams. Unsupported param
+     *                      indices will be ignored.
+     * \param heapParams    a list of params where to which the supported heap parameters will be
+     *                      appended in the order they appear in heapParamIndices.
+     *
+     * \retval C2_OK        all parameters could be queried
+     * \retval C2_BAD_INDEX all supported parameters could be queried, but some parameters were not
+     *                      supported
+     * \retval C2_NO_MEMORY could not allocate memory for a supported parameter
+     * \retval C2_CORRUPTED some unknown error prevented the querying of the parameters
+     *                      (unexpected)
+     */
+    virtual c2_status_t query_sm(
+        const std::vector<C2Param*> &stackParams,
+        const std::vector<C2Param::Index> &heapParamIndices,
+        std::vector<std::unique_ptr<C2Param>>* const heapParams) const = 0;
+
+    /**
+     * Sets a set of system-wide parameters.
+     *
+     * \note There are no settable system-wide parameters defined thus far, but may be added in the
+     * future.
+     *
+     * Tuning is performed at best effort: the store SHALL update all supported configuration at
+     * best effort (unless configured otherwise) and skip unsupported ones. Any errors are
+     * communicated in the return value and in |failures|.
+     *
+     * \note Parameter tuning DOES depend on the order of the tuning parameters. E.g. some parameter
+     * update may allow some subsequent parameter update.
+     *
+     * This method may be momentarily blocking, but MUST return within 5ms.
+     *
+     * \param params        a list of parameter updates. These will be updated to the actual
+     *                      parameter values after the updates (this is because tuning is performed
+     *                      at best effort).
+     *                      \todo params that could not be updated are not marked here, so are
+     *                      confusing - are they "existing" values or intended to be configured
+     *                      values?
+     * \param failures      a list of parameter failures
+     *
+     * \retval C2_OK        all parameters could be updated successfully
+     * \retval C2_BAD_INDEX all supported parameters could be updated successfully, but some
+     *                      parameters were not supported
+     * \retval C2_BAD_VALUE some supported parameters could not be updated successfully because
+     *                      they contained unsupported values. These are returned in |failures|.
+     * \retval C2_NO_MEMORY some supported parameters could not be updated successfully because
+     *                      they contained unsupported values, but could not allocate a failure
+     *                      object for them.
+     * \retval C2_CORRUPTED some unknown error prevented the update of the parameters
+     *                      (unexpected)
+     */
+    virtual c2_status_t config_sm(
+            const std::vector<C2Param*> &params,
+            std::vector<std::unique_ptr<C2SettingResult>>* const failures) = 0;
+
+    // REFLECTION MECHANISM (USED FOR EXTENSION)
+    // =============================================================================================
+
+    /**
+     * Returns the parameter reflector.
+     *
+     * This is used to describe parameter fields. This is shared for all components created by
+     * this component store.
+     *
+     * This method MUST be "non-blocking" and return within 1ms.
+     *
+     * \return a shared parameter reflector object.
+     */
+    virtual std::shared_ptr<C2ParamReflector> getParamReflector() const = 0;
+
+    /**
+     * Returns the set of supported parameters.
+     *
+     * This method MUST be "non-blocking" and return within 1ms.
+     *
+     * \param[out] params a vector of supported parameters will be appended to this vector.
+     *
+     * \retval C2_OK        the operation completed successfully.
+     * \retval C2_NO_MEMORY not enough memory to complete this method.
+     */
+    virtual c2_status_t querySupportedParams_nb(
+            std::vector<std::shared_ptr<C2ParamDescriptor>> * const params) const = 0;
+
+    /**
+     * Retrieves the supported values for the queried fields.
+     *
+     * Client SHALL set the parameter-field specifier and the type of supported values query (e.g.
+     * currently supported values, or potential supported values) in fields.
+     * Upon return the store SHALL fill in the supported values for the fields listed as well
+     * as a status for each field. Store shall process all fields queried even if some queries
+     * fail.
+     *
+     * This method may be momentarily blocking, but MUST return within 5ms.
+     *
+     * \param[in out] fields a vector of fields descriptor structures.
+     *
+     * \retval C2_OK        the operation completed successfully.
+     * \retval C2_BAD_INDEX at least one field was not recognized as a component store field
+     */
+    virtual c2_status_t querySupportedValues_sm(
+            std::vector<C2FieldSupportedValuesQuery> &fields) const = 0;
+
+    virtual ~C2ComponentStore() = default;
+};
+
+// ================================================================================================
+
+/// @}
+
+#endif  // C2COMPONENT_H_