Add suport for content steering (#162)

- Add tag EXT-X-CONTENT-STEERING
- Add EXT-X-STREAM-INF's attribute PATHWAY-ID

Author: bbert

parse.ts

@@ -18,7 +18,8 @@ import {
   Segment,
   PartialSegment,
   PrefetchSegment,
-  RenditionReport
+  RenditionReport,
+  ContentSteering
 } from './types';
 
 function unquote(str: string | undefined) {
@@ -31,6 +32,7 @@ function getTagCategory(tagName: string): TagCategory {
   switch (tagName) {
     case 'EXTM3U':
     case 'EXT-X-VERSION':
+    case 'EXT-X-CONTENT-STEERING':
       return 'Basic';
     case 'EXTINF':
     case 'EXT-X-BYTERANGE':
@@ -284,7 +286,8 @@ function parseRendition({attributes}: Tag): Rendition {
     forced: attributes['FORCED'],
     instreamId: attributes['INSTREAM-ID'],
     characteristics: attributes['CHARACTERISTICS'],
-    channels: attributes['CHANNELS']
+    channels: attributes['CHANNELS'],
+    pathwayId: attributes['PATHWAY-ID']
   });
   return rendition;
 }
@@ -342,6 +345,7 @@ function parseVariant(lines, variantAttrs, uri: string, iFrameOnly: boolean, par
     allowedCpc: variantAttrs['ALLOWED-CPC'],
     videoRange: variantAttrs['VIDEO-RANGE'],
     stableVariantId: variantAttrs['STABLE-VARIANT-ID'],
+    pathwayId: variantAttrs['STABLE-PATHWAY-ID'],
     programId: variantAttrs['PROGRAM-ID']
   });
   for (const line of lines) {
@@ -407,6 +411,12 @@ function parseMasterPlaylist(lines: Line[], params: Record<string, any>): Master
     const {name, value, attributes} = mapTo<Tag>(line);
     if (name === 'EXT-X-VERSION') {
       playlist.version = value;
+    } else if (name === 'EXT-X-CONTENT-STEERING-SERVER') {
+      const contentSteering = new ContentSteering({
+        serverUri: attributes['SERVER-URI'],
+        pathwayId: attributes['PATHWAY-ID']
+      });
+      playlist.contentSteering = contentSteering;
     } else if (name === 'EXT-X-STREAM-INF') {
       const uri = lines[index + 1];
       if (typeof uri !== 'string' || uri.startsWith('#EXT')) {

stringify.ts

@@ -12,6 +12,7 @@ import {
   SpliceInfo,
   Variant,
   PostProcess,
+  ContentSteering,
 } from './types';
 
 const ALLOW_REDUNDANCY = [
@@ -88,6 +89,9 @@ function getNumberOfDecimalPlaces(num: number) {
 }
 
 function buildMasterPlaylist(lines: LineArray, playlist: MasterPlaylist, postProcess: PostProcess | undefined) {
+  if (playlist.contentSteering) {
+    lines.push(buildContentSteeringServer(playlist.contentSteering));
+  }
   for (const sessionData of playlist.sessionDataList) {
     lines.push(buildSessionData(sessionData));
   }
@@ -103,6 +107,14 @@ function buildMasterPlaylist(lines: LineArray, playlist: MasterPlaylist, postPro
   }
 }
 
+function buildContentSteeringServer(contentSteering: ContentSteering) {
+  const attrs = [
+    `SERVER-URI="${contentSteering.serverUri}"`,
+    `PATHWAY-ID="${contentSteering.pathwayId}"`
+  ];
+  return `#EXT-X-CONTENT-STEERING:${attrs.join(',')}`;
+}
+
 function buildSessionData(sessionData: SessionData) {
   const attrs = [`DATA-ID="${sessionData.id}"`];
   if (sessionData.language) {
@@ -200,6 +212,9 @@ function buildVariant(lines: LineArray, variant: Variant) {
   if (variant.stableVariantId) {
     attrs.push(`STABLE-VARIANT-ID="${variant.stableVariantId}"`);
   }
+  if (variant.pathwayId) {
+    attrs.push(`PATHWAY-ID="${variant.pathwayId}"`);
+  }
   if (variant.programId) {
     attrs.push(`PROGRAM-ID=${variant.programId}`);
   }

types.ts

@@ -15,6 +15,7 @@ class Rendition {
   instreamId?: string;
   characteristics?: string;
   channels?: string;
+  pathwayId?: string;
 
   constructor({
     type, // required
@@ -28,7 +29,8 @@ class Rendition {
     forced,
     instreamId, // required if type=CLOSED-CAPTIONS
     characteristics,
-    channels
+    channels,
+    pathwayId
   }: Rendition) {
     utils.PARAMCHECK(type, groupId, name);
     utils.CONDITIONALASSERT([type === 'SUBTITLES', uri], [type === 'CLOSED-CAPTIONS', instreamId], [type === 'CLOSED-CAPTIONS', !uri], [forced, type === 'SUBTITLES']);
@@ -44,6 +46,7 @@ class Rendition {
     this.instreamId = instreamId;
     this.characteristics = characteristics;
     this.channels = channels;
+    this.pathwayId = pathwayId;
   }
 }
 
@@ -60,6 +63,7 @@ class Variant {
   allowedCpc: AllowedCpc[];
   videoRange: 'SDR' | 'HLG' | 'PQ';
   stableVariantId: string;
+  pathwayId: string;
   programId: any;
   audio: (Rendition & {type: 'AUDIO'})[];
   video: (Rendition & {type: 'VIDEO'})[];
@@ -80,6 +84,7 @@ class Variant {
     allowedCpc,
     videoRange,
     stableVariantId,
+    pathwayId,
     programId,
     audio = [],
     video = [],
@@ -101,6 +106,7 @@ class Variant {
     this.allowedCpc = allowedCpc;
     this.videoRange = videoRange;
     this.stableVariantId = stableVariantId;
+    this.pathwayId = pathwayId;
     this.programId = programId;
     this.audio = audio;
     this.video = video;
@@ -156,6 +162,19 @@ class Key {
   }
 }
 
+class ContentSteering {
+  serverUri: string;
+  pathwayId: string;
+
+  constructor({
+    serverUri,
+    pathwayId
+  }: ContentSteering) {
+    this.serverUri = serverUri;
+    this.pathwayId = pathwayId;
+  }
+}
+
 export type Byterange = {
   length: number;
   offset: number;
@@ -281,19 +300,22 @@ class MasterPlaylist extends Playlist {
   currentVariant?: number;
   sessionDataList: SessionData[];
   sessionKeyList: Key[];
+  contentSteering?: ContentSteering;
 
   constructor(params: Partial<MasterPlaylist> = {}) {
     super({...params, isMasterPlaylist: true});
     const {
       variants = [],
       currentVariant,
       sessionDataList = [],
-      sessionKeyList = []
+      sessionKeyList = [],
+      contentSteering = undefined
     } = params;
     this.variants = variants;
     this.currentVariant = currentVariant;
     this.sessionDataList = sessionDataList;
     this.sessionKeyList = sessionKeyList;
+    this.contentSteering = contentSteering;
   }
 }
 
@@ -493,7 +515,8 @@ export {
   Segment,
   PartialSegment,
   PrefetchSegment,
-  RenditionReport
+  RenditionReport,
+  ContentSteering
 };
 
 export type AllowedCpc = {