+++ /dev/null
-
-# Piper audio feature extraction: schema for low-level operation
-#
-# This file is formatted to 130 characters width, in order to fit the
-# comments next to the schema definitions.
-#
-# Copyright (c) 2015-2017 Queen Mary, University of London, provided
-# under a BSD-style licence. See the file COPYING for details.
-
-@0xc4b1c6c44c999206;
-
-using Cxx = import "/capnp/c++.capnp";
-$Cxx.namespace("piper");
-
-struct Basic {
- # Basic metadata common to many Piper structures.
-
- identifier @0 :Text; # A computer-readable string. Must match the regex /^[a-zA-Z0-9_-]+$/.
- name @1 :Text; # A short human-readable name or label. Must be present.
- description @2 :Text; # An optional human-readable descriptive text that may accompany the name.
-}
-
-struct ParameterDescriptor {
- # Properties of an adjustable parameter. A parameter's value is just a single
- # float, but the descriptor explains how to interpret and present that value.
- # A Piper feature extractor has a static list of parameters. The properties of
- # a given parameter never change, in contrast to output descriptors, which
- # may have different properties depending on the configuration of the extractor.
-
- basic @0 :Basic; # Basic metadata about the parameter.
- unit @1 :Text; # Human-recognisable unit of the parameter (e.g. Hz). May be left empty.
- minValue @2 :Float32 = 0.0; # Minimum value. Must be provided.
- maxValue @3 :Float32 = 0.0; # Maximum value. Must be provided.
- defaultValue @4 :Float32 = 0.0; # Default if the parameter is not set to anything else. Must be provided.
- isQuantized @5 :Bool = false; # True if parameter values are quantized to a particular resolution.
- quantizeStep @6 :Float32 = 0.0; # Quantization resolution, if isQuantized.
- valueNames @7 :List(Text) = []; # Optional human-readable labels for the values, if isQuantized.
-}
-
-enum SampleType {
- # How returned features are spaced on the input timeline.
-
- oneSamplePerStep @0; # Each process input returns a feature aligned with that input's timestamp.
- fixedSampleRate @1; # Features are equally spaced at a given sample rate.
- variableSampleRate @2; # Features have their own individual timestamps.
-}
-
-struct StaticOutputDescriptor {
-
- # Properties of an output, that is, a single stream of features
- # produced in response to process and finish requests. A feature
- # extractor may have any number of outputs, and it always
- # calculates and returns features from all of them when
- # processing; this is useful in cases where more than one feature
- # can be easily calculated using a single method.
- #
- # This structure contains the properties of an output that are
- # static, i.e. that do not depend on the parameter values provided
- # at configuration, excluding the Basic struct parameters like id
- # and description. The Basic struct properties are not included
- # for historical reasons: they were already referenced separately
- # in the OutputDescriptor and ExtractorStaticData before this
- # struct was introduced.
-
- typeURI @0 :Text; # URI indicating the sort of feature that this output returns (see docs).
-}
-
-struct ConfiguredOutputDescriptor {
- # Properties of an output, that is, a single stream of features produced
- # in response to process and finish requests. A feature extractor may
- # have any number of outputs, and it always calculates and returns features
- # from all of them when processing; this is useful in cases where more
- # than one feature can be easily calculated using a single method.
- # This structure contains the properties of an output that are not static,
- # i.e. that may depend on the parameter values provided at configuration.
-
- unit @0 :Text; # Human-recognisable unit of the bin values in output features. May be empty.
- hasFixedBinCount @1 :Bool = false; # True if this output has an equal number of values in each returned feature.
- binCount @2 :Int32 = 0; # Number of values per feature for this output, if hasFixedBinCount.
- binNames @3 :List(Text) = []; # Optional human-readable labels for the value bins, if hasFixedBinCount.
- hasKnownExtents @4 :Bool = false; # True if all feature values fall within the same fixed min/max range.
- minValue @5 :Float32 = 0.0; # Minimum value in range for any value from this output, if hasKnownExtents.
- maxValue @6 :Float32 = 0.0; # Maximum value in range for any value from this output, if hasKnownExtents.
- isQuantized @7 :Bool = false; # True if feature values are quantized to a particular resolution.
- quantizeStep @8 :Float32 = 0.0; # Quantization resolution, if isQuantized.
- sampleType @9 :SampleType; # How returned features from this output are spaced on the input timeline.
- sampleRate @10 :Float32 = 0.0; # Sample rate (features per second) if sampleType == fixedSampleRate.
- hasDuration @11 :Bool = false; # True if features returned from this output will have a duration.
-}
-
-struct OutputDescriptor {
- # All the properties of an output, both static (the basic metadata and static
- # descriptor) and potentially dependent on configuration parameters (the
- # configured descriptor).
-
- basic @0 :Basic; # Basic metadata about the output.
- configured @1 :ConfiguredOutputDescriptor; # Properties of the output that may depend on configuration parameters.
- static @2 :StaticOutputDescriptor; # Properties (other than Basic) that do not depend on parameters.
-}
-
-enum InputDomain {
- # Whether a feature extractor requires time-domain audio input (i.e.
- # "normal" or "unprocessed" audio samples) or frequency-domain input
- # (i.e. resulting from windowed, usually overlapping, short-time
- # Fourier transforms).
-
- timeDomain @0; # The plugin requires time-domain audio samples as input.
- frequencyDomain @1; # The plugin requires input to have been pre-processed using windowed STFTs.
-}
-
-struct ExtractorStaticData {
- # Static properties of a feature extractor. That is, metadata about the
- # extractor that are the same regardless of how you configure or run it.
-
- key @0 :Text; # String that "globally" identifies the extractor, used to load it (see docs).
- basic @1 :Basic; # Basic metadata about the extractor.
- maker @2 :Text; # Human-readable text naming the author or vendor of the extractor.
- rights @3 :Text; # Human-readable summary of copyright and/or licensing terms for the extractor.
- version @4 :Int32; # Version number of extractor; must increase if new algorithm changes results.
- category @5 :List(Text); # List of general->specific category labels for this extractor (see docs).
- minChannelCount @6 :Int32; # Minimum number of input channels of audio this extractor can accept.
- maxChannelCount @7 :Int32; # Maximum number of input channels of audio this extractor can accept.
- parameters @8 :List(ParameterDescriptor); # List of configurable parameter properties for the feature extractor.
- programs @9 :List(Text); # List of predefined programs. For backward-compatibility, not recommended.
- inputDomain @10 :InputDomain; # Whether the extractor requires time-domain or frequency-domain input audio.
- basicOutputInfo @11 :List(Basic); # Basic metadata about all of the outputs of the extractor.
-
- struct SOPair {
- # A mapping between output identifier and static descriptor for
- # that output.
-
- output @0 :Text; # Output id, matching the output's descriptor's basic identifier.
- static @1 :StaticOutputDescriptor;
- }
-
- staticOutputInfo @12 :List(SOPair); # Static descriptors for all outputs that have any static metadata.
-}
-
-struct RealTime {
- # Time structure. When used as a timestamp, this is relative to "start
- # of audio".
-
- sec @0 :Int32 = 0; # Number of seconds.
- nsec @1 :Int32 = 0; # Number of nanoseconds. Must have same sign as sec unless sec == 0.
-}
-
-struct ProcessInput {
- # Audio and timing input data provided to a process request.
-
- inputBuffers @0 :List(List(Float32)); # A single block of audio data (time or frequency domain) for each channel.
- timestamp @1 :RealTime; # Time of start of block (time-domain) or "centre" of it (frequency-domain).
-}
-
-struct Feature {
- # A single feature calculated and returned from a process or finish request.
-
- hasTimestamp @0 :Bool = false; # True if feature has a timestamp. Must be true for a variableSampleRate output.
- timestamp @1 :RealTime; # Timestamp of feature, if hasTimestamp.
- hasDuration @2 :Bool = false; # True if feature has a duration. Must be true if output's hasDuration is true.
- duration @3 :RealTime; # Duration of feature, if hasDuration.
- label @4 :Text; # Optional human-readable text attached to feature.
- featureValues @5 :List(Float32) = []; # The feature values themselves (of size binCount, if output hasFixedBinCount).
-}
-
-struct FeatureSet {
- # The set of all features, across all outputs, calculated and returned from
- # a single process or finish request.
-
- struct FSPair {
- # A mapping between output identifier and ordered list of features for
- # that output.
-
- output @0 :Text; # Output id, matching the output's descriptor's basic identifier.
- features @1 :List(Feature) = []; # Features calculated for that output during the current request, in time order.
- }
-
- featurePairs @0 :List(FSPair); # The feature lists for all outputs for which any features have been calculated.
-}
-
-struct Framing {
- # Determines how audio should be split up into individual buffers for input.
- # If the feature extractor accepts frequency-domain input, then this
- # applies prior to the STFT transform.
- #
- # These values are sometimes mandatory, but in other contexts one or both may
- # be set to zero to mean "don't care". See documentation for structures that
- # include a framing field for details.
-
- blockSize @0 :Int32; # Number of time-domain audio samples per buffer (on each channel).
- stepSize @1 :Int32; # Number of samples to advance between buffers: equals blockSize for no overlap.
-}
-
-struct Configuration {
- # Bundle of parameter values and other configuration data for a feature-
- # extraction procedure.
-
- struct PVPair {
- # A mapping between parameter identifier and value.
-
- parameter @0 :Text; # Parameter id, matching the parameter's descriptor's basic identifier.
- value @1 :Float32; # Value to set parameter to (within constraints given in parameter descriptor).
- }
-
- parameterValues @0 :List(PVPair); # Values for all parameters, or at least any that are to change from defaults.
- currentProgram @1 :Text; # Selection of predefined program. For backward-compatibility, not recommended.
- channelCount @2 :Int32; # Number of audio channels of input.
- framing @3 :Framing; # Step and block size for framing the input.
-}
-
-enum AdapterFlag {
- # Flags that may be used when requesting a server to load a feature
- # extractor, to ask the server to do some of the work of framing and input
- # conversion instead of leaving it to the client side. These affect the
- # apparent behaviour of the loaded extractor.
-
- adaptInputDomain @0; # Input-domain conversion, so the extractor always expects time-domain input.
- adaptChannelCount @1; # Channel mixing or duplication, so any number of input channels is acceptable.
- adaptBufferSize @2; # Framing, so the extractor accepts any blockSize of non-overlapping buffers.
-}
-
-const adaptAllSafe :List(AdapterFlag) =
- [ adaptInputDomain, adaptChannelCount ];
- # The set of adapter flags that can always be applied, leaving results unchanged.
-
-const adaptAll :List(AdapterFlag) =
- [ adaptInputDomain, adaptChannelCount, adaptBufferSize ];
- # The set of adapter flags that may cause "equivalent" results to be returned (see documentation).
-
-struct ListRequest {
- # Request a server to provide a list of available feature extractors.
-
- from @0 :List(Text); # If non-empty, provide only extractors found in the given list of "libraries".
-}
-
-struct ListResponse {
- # Response to a successful list request.
-
- available @0 :List(ExtractorStaticData); # List of static data about available feature extractors.
-}
-
-struct LoadRequest {
- # Request a server to load a feature extractor and return a handle to it.
-
- key @0 :Text; # Key as found in the extractor's static data structure.
- inputSampleRate @1 :Float32; # Sample rate for input audio. Properties of the extractor may depend on this.
- adapterFlags @2 :List(AdapterFlag); # Set of optional flags to make any framing and input conversion requests.
-}
-
-struct LoadResponse {
- # Response to a successful load request.
-
- handle @0 :Int32; # Handle to be used to refer to the loaded feature extractor in future requests.
- staticData @1 :ExtractorStaticData; # Static data about this feature extractor, identical to that in list response.
- defaultConfiguration @2 :Configuration; # Extractor's default parameter values and preferred input framing.
-}
-
-struct ConfigurationRequest {
- # Request a server to configure a loaded feature extractor and prepare
- # it for use. This request must be carried out on a feature extractor
- # before any process request can be made.
-
- handle @0 :Int32; # Handle as returned in the load response from the loading of this extractor.
- configuration @1 :Configuration; # Bundle of parameter values to set, and client's preferred input framing.
-}
-
-struct ConfigurationResponse {
- # Response to a successful configuration request.
-
- handle @0 :Int32; # Handle of extractor, as passed in the configuration request.
- outputs @1 :List(OutputDescriptor); # Full set of properties of all outputs following configuration.
- framing @2 :Framing; # Input framing that must be used for subsequent process requests.
-}
-
-struct ProcessRequest {
- # Request a server to process a buffer of audio using a loaded and
- # configured feature extractor.
-
- handle @0 :Int32; # Handle as returned in the load response from the loading of this extractor.
- processInput @1 :ProcessInput; # Audio in the input domain, with framing as in the configuration response.
-}
-
-struct ProcessResponse {
- # Response to a successful process request.
-
- handle @0 :Int32; # Handle of extractor, as passed in the process request.
- features @1 :FeatureSet; # All features across all outputs calculated during this process request.
-}
-
-struct FinishRequest {
- # Request a server to finish processing and unload a loaded feature
- # extractor. This request may be made at any time -- the extractor does
- # not have to have been configured or used. The extractor handle cannot
- # be used again with this server afterwards.
-
- handle @0 :Int32; # Handle as returned in the load response from the loading of this extractor.
-}
-
-struct FinishResponse {
- # Response to a successful finish request.
-
- handle @0 :Int32; # Handle of extractor, as passed in the finish request. May not be used again.
- features @1 :FeatureSet; # Features the extractor has calculated now that it knows all input has ended.
-}
-
-struct Error {
- # Response to any request that fails.
-
- code @0 :Int32; # Error code.
- message @1 :Text; # Error message.
-}
-
-struct RpcRequest {
- # Request bundle for use when using Cap'n Proto serialisation without
- # Cap'n Proto RPC layer. For Cap'n Proto RPC, see piper.rpc.capnp.
-
- id :union {
- # Identifier used solely to associate a response packet with its
- # originating request. Server does not examine the contents of this,
- # it just copies the request id structure into the response.
-
- number @0 :Int32;
- tag @1 :Text;
- none @2 :Void;
- }
-
- request :union {
- # For more details, see the documentation for the individual
- # request structures.
-
- list @3 :ListRequest; # Provide a list of available feature extractors.
- load @4 :LoadRequest; # Load a feature extractor and return a handle to it.
- configure @5 :ConfigurationRequest; # Configure a loaded feature extractor, set parameters, and prepare it for use.
- process @6 :ProcessRequest; # Process a single fixed-size buffer of audio and return calculated features.
- finish @7 :FinishRequest; # Get any remaining features and unload the extractor.
- }
-}
-
-struct RpcResponse {
- # Response bundle for use when using Cap'n Proto serialisation without
- # Cap'n Proto RPC layer. For Cap'n Proto RPC, see piper.rpc.capnp.
-
- id :union {
- # Identifier used solely to associate a response packet with its
- # originating request. Server does not examine the contents of this,
- # it just copies the request id structure into the response.
-
- number @0 :Int32;
- tag @1 :Text;
- none @2 :Void;
- }
-
- response :union {
- # For more details, see the documentation for the individual
- # response structures.
-
- error @3 :Error; # The request (of whatever type) failed.
- list @4 :ListResponse; # List succeeded: here is static data about the requested extractors.
- load @5 :LoadResponse; # Load succeeded: here is a handle for the loaded extractor.
- configure @6 :ConfigurationResponse;# Configure succeeded: ready to process, here are values such as block size.
- process @7 :ProcessResponse; # Process succeeded: here are all features calculated from this input block.
- finish @8 :FinishResponse; # Finish succeeded: extractor unloaded, here are all remaining features.
- }
-}
-
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