/// <reference types="node" />
/**
 * Stores text of an individual token, along with its timing information
 */
export interface TokenMetadata {
    /** The text corresponding to this token */
    text: string;
    /** Position of the token in units of 20ms */
    timestep: number;
    /** Position of the token in seconds */
    start_time: number;
}
/**
 * A single transcript computed by the model, including a confidence value and
 * the metadata for its constituent tokens.
 */
export interface CandidateTranscript {
    tokens: TokenMetadata[];
    /**
     * Approximated confidence value for this transcription. This is roughly the
     * sum of the acoustic model logit values for each timestep/token that
     * contributed to the creation of this transcription.
     */
    confidence: number;
}
/**
 * An array of CandidateTranscript objects computed by the model.
 */
export interface Metadata {
    transcripts: CandidateTranscript[];
}
/**
 * Provides an interface to a Coqui STT stream. The constructor cannot be called
 * directly, use :js:func:`Model.createStream`.
 */
declare class StreamImpl {
    /**
     * @param nativeStream SWIG wrapper for native StreamingState object.
     */
    constructor(nativeStream: object);
    /**
     * Feed audio samples to an ongoing streaming inference.
     *
     * @param aBuffer An array of 16-bit, mono raw audio samples at the
     *                 appropriate sample rate (matching what the model was trained on).
     */
    feedAudioContent(aBuffer: Buffer): void;
    /**
     * Compute the intermediate decoding of an ongoing streaming inference.
     *
     * @return The STT intermediate result.
     */
    intermediateDecode(): string;
    /**
     * Compute the intermediate decoding of an ongoing streaming inference, return results including metadata.
     *
     * @param aNumResults Maximum number of candidate transcripts to return. Returned list might be smaller than this. Default value is 1 if not specified.
     *
     * @return :js:func:`Metadata` object containing multiple candidate transcripts. Each transcript has per-token metadata including timing information. The user is responsible for freeing Metadata by calling :js:func:`FreeMetadata`. Returns undefined on error.
     */
    intermediateDecodeWithMetadata(aNumResults?: number): Metadata;
    /**
     * EXPERIMENTAL: Compute the intermediate decoding of an ongoing streaming inference, flushing buffers first. This ensures that all audio that has been streamed so far is included in the result, but is more expensive than intermediateDecode() because buffers are processed through the acoustic model.
     *
     * @return The STT intermediate result.
     */
    intermediateDecodeFlushBuffers(): string;
    /**
     * EXPERIMENTAL: Compute the intermediate decoding of an ongoing streaming inference, flushing buffers first. This ensures that all audio that has been streamed so far is included in the result, but is more expensive than intermediateDecodeWithMetadata() because buffers are processed through the acoustic model. Returns results including metadata.
     *
     * @param aNumResults Maximum number of candidate transcripts to return. Returned list might be smaller than this. Default value is 1 if not specified.
     *
     * @return :js:func:`Metadata` object containing multiple candidate transcripts. Each transcript has per-token metadata including timing information. The user is responsible for freeing Metadata by calling :js:func:`FreeMetadata`. Returns undefined on error.
     */
    intermediateDecodeWithMetadataFlushBuffers(aNumResults?: number): Metadata;
    /**
     * Compute the final decoding of an ongoing streaming inference and return the result. Signals the end of an ongoing streaming inference.
     *
     * @return The STT result.
     *
     * This method will free the stream, it must not be used after this method is called.
     */
    finishStream(): string;
    /**
     * Compute the final decoding of an ongoing streaming inference and return the results including metadata. Signals the end of an ongoing streaming inference.
     *
     * @param aNumResults Maximum number of candidate transcripts to return. Returned list might be smaller than this. Default value is 1 if not specified.
     *
     * @return Outputs a :js:func:`Metadata` struct of individual letters along with their timing information. The user is responsible for freeing Metadata by calling :js:func:`FreeMetadata`.
     *
     * This method will free the stream, it must not be used after this method is called.
     */
    finishStreamWithMetadata(aNumResults?: number): Metadata;
}
/**
 * Exposes the type of Stream without actually exposing the class.
 * Because the Stream class should not be instantiated directly,
 * but instead be created via :js:func:`Model.createStream`.
 */
export declare type Stream = StreamImpl;
/**
 * An object providing an interface to a trained Coqui STT model.
 */
export declare class Model {
    /**
     * @param aModelData Either the path to the frozen model graph or the frozen model's bytes.
     * @param loadFromBytes Wheter to load the model from bytes or from a file.
     *
     * @throws on error
     */
    constructor(aModelData: string | Uint8Array, loadFromBytes?: boolean);
    /**
     * Get beam width value used by the model. If :js:func:`Model.setBeamWidth` was
     * not called before, will return the default value loaded from the model file.
     *
     * @return Beam width value used by the model.
     */
    beamWidth(): number;
    /**
     * Set beam width value used by the model.
     *
     * @param aBeamWidth The beam width used by the model. A larger beam width value generates better results at the cost of decoding time.
     *
     * @throws on error
     */
    setBeamWidth(aBeamWidth: number): void;
    /**
     * Add a hot-word and its boost.
     *
     * Words that don't occur in the scorer (e.g. proper nouns) or strings that contain spaces won't be taken into account.
     *
     * @param aWord word
     * @param aBoost boost Positive value increases and negative reduces chance of a word occuring in a transcription. Excessive positive boost might lead to splitting up of letters of the word following the hot-word.
     *
     * @throws on error
     */
    addHotWord(aWord: string, aBoost: number): void;
    /**
     * Erase entry for hot-word
     *
     * @param aWord word
     *
     * @throws on error
     */
    eraseHotWord(aWord: string): void;
    /**
     * Clear all hot-word entries
     *
     * @throws on error
     */
    clearHotWords(): void;
    /**
     * Return the sample rate expected by the model.
     *
     * @return Sample rate.
     */
    sampleRate(): number;
    /**
     * Enable decoding using an external scorer.
     *
     * @param aScorerPath The path to the external scorer file.
     *
     * @throws on error
     */
    enableExternalScorer(aScorerPath: string): void;
    /**
     * Disable decoding using an external scorer.
     *
     * @throws on error
     */
    disableExternalScorer(): void;
    /**
     * Set hyperparameters alpha and beta of the external scorer.
     *
     * @param aLMAlpha The alpha hyperparameter of the CTC decoder. Language Model weight.
     * @param aLMBeta The beta hyperparameter of the CTC decoder. Word insertion weight.
     *
     * @throws on error
     */
    setScorerAlphaBeta(aLMAlpha: number, aLMBeta: number): void;
    /**
     * Use the Coqui STT model to perform Speech-To-Text.
     *
     * @param aBuffer A 16-bit, mono raw audio signal at the appropriate sample rate (matching what the model was trained on).
     *
     * @return The STT result. Returns undefined on error.
     */
    stt(aBuffer: Buffer): string;
    /**
     * Use the Coqui STT model to perform Speech-To-Text and output metadata
     * about the results.
     *
     * @param aBuffer A 16-bit, mono raw audio signal at the appropriate sample rate (matching what the model was trained on).
     * @param aNumResults Maximum number of candidate transcripts to return. Returned list might be smaller than this.
     * Default value is 1 if not specified.
     *
     * @return :js:func:`Metadata` object containing multiple candidate transcripts. Each transcript has per-token metadata including timing information.
     * The user is responsible for freeing Metadata by calling :js:func:`FreeMetadata`. Returns undefined on error.
     */
    sttWithMetadata(aBuffer: Buffer, aNumResults?: number): Metadata;
    /**
     * Create a new streaming inference state. One can then call :js:func:`StreamImpl.feedAudioContent` and :js:func:`StreamImpl.finishStream` on the returned stream object.
     *
     * @return a :js:func:`StreamImpl` object that represents the streaming state.
     *
     * @throws on error
     */
    createStream(): StreamImpl;
}
/**
 * Frees associated resources and destroys model object.
 *
 * @param model A model pointer returned by :js:func:`Model`
 *
 */
export declare function FreeModel(model: Model): void;
/**
 * Free memory allocated for metadata information.
 *
 * @param metadata Object containing metadata as returned by :js:func:`Model.sttWithMetadata` or :js:func:`StreamImpl.finishStreamWithMetadata`
 */
export declare function FreeMetadata(metadata: Metadata): void;
/**
 * Destroy a streaming state without decoding the computed logits. This
 * can be used if you no longer need the result of an ongoing streaming
 * inference and don't want to perform a costly decode operation.
 *
 * @param stream A streaming state pointer returned by :js:func:`Model.createStream`.
 */
export declare function FreeStream(stream: StreamImpl): void;
/**
 * Returns the version of this library. The returned version is a semantic
 * version (SemVer 2.0.0).
 */
export declare function Version(): string;
export {};