rx-player/src/parsers/manifest/dash/wasm-parser/ts/generators/EventStream.ts

Canal+ HTML5 Video Player

/**
 * Copyright 2015 CANAL+ Group
 *
 * 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.
 */

import noop from "../../../../../../utils/noop";
import type {
  IEventStreamAttributes,
  IEventStreamChildren,
  IEventStreamEventIntermediateRepresentation,
} from "../../../node_parser_types";
import type { IAttributeParser, IChildrenParser } from "../parsers_stack";
import type ParsersStack from "../parsers_stack";
import { AttributeName, TagName } from "../types";
import { parseString } from "../utils";

/**
 * Generate a "children parser" once inside a `EventStream` node.
 * @param {Object} childrenObj
 * @param {WebAssembly.Memory} linearMemory
 * @param {ParsersStack} parsersStack
 * @param {ArrayBuffer} fullMpd
 * @returns {Function}
 */
export function generateEventStreamChildrenParser(
  childrenObj: IEventStreamChildren,
  linearMemory: WebAssembly.Memory,
  parsersStack: ParsersStack,
  fullMpd: ArrayBuffer,
): IChildrenParser {
  return function onRootChildren(nodeId: number) {
    switch (nodeId) {
      case TagName.EventStreamElt: {
        const event = {};
        childrenObj.events.push(event);
        const attrParser = generateEventAttrParser(event, linearMemory, fullMpd);
        parsersStack.pushParsers(nodeId, noop, attrParser);
        break;
      }

      default:
        // Allows to make sure we're not mistakenly closing a re-opened
        // tag.
        parsersStack.pushParsers(nodeId, noop, noop);
        break;
    }
  };
}

/**
 * @param {Object} esAttrs
 * @param {WebAssembly.Memory} linearMemory
 * @returns {Function}
 */
export function generateEventStreamAttrParser(
  esAttrs: IEventStreamAttributes,
  linearMemory: WebAssembly.Memory,
): IAttributeParser {
  const textDecoder = new TextDecoder();
  return function onEventStreamAttribute(attr: number, ptr: number, len: number) {
    const dataView = new DataView(linearMemory.buffer);
    switch (attr) {
      case AttributeName.SchemeIdUri:
        esAttrs.schemeIdUri = parseString(textDecoder, linearMemory.buffer, ptr, len);
        break;
      case AttributeName.SchemeValue:
        esAttrs.value = parseString(textDecoder, linearMemory.buffer, ptr, len);
        break;
      case AttributeName.TimeScale:
        esAttrs.timescale = dataView.getFloat64(ptr, true);
        break;
      case AttributeName.Namespace: {
        const xmlNs = { key: "", value: "" };
        let offset = ptr;
        const keySize = dataView.getUint32(offset);
        offset += 4;

        xmlNs.key = parseString(textDecoder, linearMemory.buffer, offset, keySize);
        offset += keySize;

        const valSize = dataView.getUint32(offset);
        offset += 4;
        xmlNs.value = parseString(textDecoder, linearMemory.buffer, offset, valSize);

        if (esAttrs.namespaces === undefined) {
          esAttrs.namespaces = [xmlNs];
        } else {
          esAttrs.namespaces.push(xmlNs);
        }
        break;
      }
    }
  };
}

/**
 * @param {Object} eventAttr
 * @param {WebAssembly.Memory} linearMemory
 * @param {ArrayBuffer} fullMpd
 * @returns {Function}
 */
function generateEventAttrParser(
  eventAttr: IEventStreamEventIntermediateRepresentation,
  linearMemory: WebAssembly.Memory,
  fullMpd: ArrayBuffer,
): IAttributeParser {
  const textDecoder = new TextDecoder();
  return function onEventStreamAttribute(attr: number, ptr: number, len: number) {
    const dataView = new DataView(linearMemory.buffer);
    switch (attr) {
      case AttributeName.EventPresentationTime:
        eventAttr.presentationTime = dataView.getFloat64(ptr, true);
        break;
      case AttributeName.Duration:
        eventAttr.duration = dataView.getFloat64(ptr, true);
        break;
      case AttributeName.Id:
        eventAttr.id = parseString(textDecoder, linearMemory.buffer, ptr, len);
        break;
      case AttributeName.EventStreamEltRange: {
        const rangeStart = dataView.getFloat64(ptr, true);
        const rangeEnd = dataView.getFloat64(ptr + 8, true);
        eventAttr.eventStreamData = fullMpd.slice(rangeStart, rangeEnd);
        break;
      }
    }
  };
}