init

react/features/base/lastn/actionTypes.ts

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+/**
+ * The type of (redux) action which sets the last-n for the conference.
+ *
+ * {
+ *     type: SET_LAST_N,
+ *     lastN: number
+ * }
+ */
+export const SET_LAST_N = 'SET_LAST_N';

react/features/base/lastn/actions.ts

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+import { SET_LAST_N } from './actionTypes';
+
+/**
+ * Sets the last-n, i.e., the number of remote videos to be requested from the bridge for the conference.
+ *
+ * @param {number} lastN - The number of remote videos to be requested.
+ * @returns {{
+ *     type: SET_LAST_N,
+ *     lastN: number
+ * }}
+ */
+export function setLastN(lastN: number) {
+    return {
+        type: SET_LAST_N,
+        lastN
+    };
+}

react/features/base/lastn/functions.ts

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+import { VIDEO_QUALITY_LEVELS } from '../../video-quality/constants';
+
+/**
+ * Determines the lastN value to be used for the conference based on the video quality selected.
+ *
+ * @param {string} qualityLevel - Quality level (height) selected.
+ * @param {number} channelLastN - LastN value set for the whole conference.
+ * @returns {number} LastN value applicable to the quality level specified.
+ */
+export function getLastNForQualityLevel(qualityLevel: number, channelLastN: number) {
+    let lastN = channelLastN;
+
+    const videoQualityLevels = Object.values(VIDEO_QUALITY_LEVELS);
+
+    for (const lvl in videoQualityLevels) {
+        if (videoQualityLevels.hasOwnProperty(lvl)
+            && qualityLevel === videoQualityLevels[lvl]
+            && Number(lvl) > 1) {
+            lastN = Math.floor(channelLastN / Math.pow(2, Number(lvl) - 1));
+        }
+    }
+
+    return lastN;
+}

react/features/base/lastn/logger.ts

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+import { getLogger } from '../logging/functions';
+
+export default getLogger('features/base/lastn');

react/features/base/lastn/middleware.ts

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+import { debounce } from 'lodash-es';
+
+import { IStore } from '../../app/types';
+import { SET_FILMSTRIP_ENABLED } from '../../filmstrip/actionTypes';
+import { APP_STATE_CHANGED } from '../../mobile/background/actionTypes';
+import {
+    SET_CAR_MODE,
+    VIRTUAL_SCREENSHARE_REMOTE_PARTICIPANTS_UPDATED
+} from '../../video-layout/actionTypes';
+import { SET_AUDIO_ONLY } from '../audio-only/actionTypes';
+import { CONFERENCE_JOINED } from '../conference/actionTypes';
+import { getParticipantById } from '../participants/functions';
+import MiddlewareRegistry from '../redux/MiddlewareRegistry';
+
+import { setLastN } from './actions';
+import logger from './logger';
+
+/**
+ * Updates the last N value in the conference based on the current state of the redux store.
+ *
+ * @param {Store} store - The redux store.
+ * @private
+ * @returns {void}
+ */
+const _updateLastN = debounce(({ dispatch, getState }: IStore) => {
+    const state = getState();
+    const { conference } = state['features/base/conference'];
+
+    if (!conference) {
+        logger.debug('There is no active conference, not updating last N');
+
+        return;
+    }
+
+    const { enabled: audioOnly } = state['features/base/audio-only'];
+    const { appState } = state['features/mobile/background'] || {};
+    const { enabled: filmStripEnabled } = state['features/filmstrip'];
+    const config = state['features/base/config'];
+    const { carMode } = state['features/video-layout'];
+
+    // Select the (initial) lastN value based on the following preference order.
+    // 1. The last-n value from 'startLastN' if it is specified in config.js
+    // 2. The last-n value from 'channelLastN' if specified in config.js.
+    // 3. -1 as the default value.
+    let lastNSelected = config.startLastN ?? (config.channelLastN ?? -1);
+
+    // Because this is shared, on web appState is always undefined,
+    // meaning that it is never active
+    if (navigator.product === 'ReactNative' && (appState !== 'active' || carMode)) {
+        lastNSelected = 0;
+    } else if (audioOnly) {
+        const { remoteScreenShares, tileViewEnabled } = state['features/video-layout'];
+        const largeVideoParticipantId = state['features/large-video'].participantId;
+        const largeVideoParticipant
+            = largeVideoParticipantId ? getParticipantById(state, largeVideoParticipantId) : undefined;
+
+        // Use tileViewEnabled state from redux here instead of determining if client should be in tile
+        // view since we make an exception only for screenshare when in audio-only mode. If the user unpins
+        // the screenshare, lastN will be set to 0 here. It will be set to 1 if screenshare has been auto pinned.
+        if (!tileViewEnabled && largeVideoParticipant && !largeVideoParticipant.local) {
+            lastNSelected = (remoteScreenShares || []).includes(largeVideoParticipantId ?? '') ? 1 : 0;
+        } else {
+            lastNSelected = 0;
+        }
+    } else if (!filmStripEnabled) {
+        lastNSelected = 1;
+    }
+
+    const { lastN } = state['features/base/lastn'];
+
+    if (lastN !== lastNSelected) {
+        dispatch(setLastN(lastNSelected));
+    }
+}, 1000); /* Don't send this more often than once a second. */
+
+
+MiddlewareRegistry.register(store => next => action => {
+    const result = next(action);
+
+    switch (action.type) {
+    case APP_STATE_CHANGED:
+    case CONFERENCE_JOINED:
+    case SET_AUDIO_ONLY:
+    case SET_CAR_MODE:
+    case SET_FILMSTRIP_ENABLED:
+    case VIRTUAL_SCREENSHARE_REMOTE_PARTICIPANTS_UPDATED:
+        _updateLastN(store);
+        break;
+    }
+
+    return result;
+});

react/features/base/lastn/reducer.ts

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+import ReducerRegistry from '../redux/ReducerRegistry';
+
+import { SET_LAST_N } from './actionTypes';
+
+export interface ILastNState {
+    lastN?: number;
+}
+
+ReducerRegistry.register<ILastNState>('features/base/lastn', (state = {}, action): ILastNState => {
+    switch (action.type) {
+    case SET_LAST_N: {
+        const { lastN } = action;
+
+        return {
+            ...state,
+            lastN
+        };
+    }
+    }
+
+    return state;
+});