import type * as grpc from '@grpc/grpc-js';
import * as apiProto from './protos/api';
export declare class TTSStreamSource implements UnderlyingByteSource {
    private readonly request;
    private readonly rpcClient;
    private readonly fallbackClient?;
    private stream?;
    readonly type = "bytes";
    private retryable;
    constructor(request: apiProto.playht.v1.ITtsRequest, rpcClient: grpc.Client, fallbackClient?: grpc.Client | undefined);
    start(controller: ReadableByteStreamController): void;
    startAndMaybeFallback(controller: ReadableByteStreamController, client: grpc.Client, fallbackClient?: grpc.Client): void;
    cancel(): void;
    end(): boolean;
}
