feat: Added operations to resolution filtering for stitcher

packages/stitcher/src/contract.ts

@@ -19,7 +19,7 @@ const sessionParams = z.object({
       }),
     )
     .optional(),
-  maxResolution: z.coerce.number().optional(),
+  resolution: z.string().optional(),
 });
 
 export const postSessionBodySchema = z

packages/stitcher/src/helpers.ts

@@ -1,4 +1,5 @@
 import { env } from "./env.js";
+import type * as hlsParser from "../extern/hls-parser/index.js";
 
 export async function isAssetAvailable(assetId: string) {
   const response = await fetch(
@@ -9,3 +10,37 @@ export async function isAssetAvailable(assetId: string) {
   );
   return response.ok;
 }
+
+export function filterByString(items: hlsParser.types.Variant[], str: string) {
+  const [operator, value] = str.split(" ");
+
+  if (operator === "<") {
+    return items.filter(
+      (item) =>
+        item.resolution && item.resolution?.height < parseInt(value, 10),
+    );
+  }
+
+  if (operator === "<=") {
+    return items.filter(
+      (item) =>
+        item.resolution && item.resolution?.height <= parseInt(value, 10),
+    );
+  }
+
+  if (operator === ">") {
+    return items.filter(
+      (item) =>
+        item.resolution && item.resolution?.height > parseInt(value, 10),
+    );
+  }
+
+  if (operator === ">=") {
+    return items.filter(
+      (item) =>
+        item.resolution && item.resolution?.height >= parseInt(value, 10),
+    );
+  }
+
+  throw new Error("Invalid filter");
+}

packages/stitcher/src/playlist.ts

@@ -3,6 +3,7 @@ import parseFilepath from "parse-filepath";
 import { env } from "./env.js";
 import { MasterPlaylist, MediaPlaylist } from "../extern/hls-parser/types.js";
 import createError from "@fastify/error";
+import { filterByString } from "./helpers.js";
 import type { Session, Interstitial, InterstitialType } from "./types.js";
 
 const PlaylistUnavailableError = createError<[string]>(
@@ -18,6 +19,13 @@ const NoVariantsError = createError(
   400,
 );
 
+const NoInterstitialsError = createError(
+  "NO_INTERSTITIALS",
+  "The playlist does not contain interstitials",
+);
+
+const InvalidFilter = createError("INVALID_FILTER", "Invalid filter");
+
 async function fetchPlaylist<T>(url: string) {
   try {
     const response = await fetch(url);
@@ -33,12 +41,13 @@ export async function formatMasterPlaylist(session: Session) {
 
   const master = await fetchPlaylist<MasterPlaylist>(url);
 
-  master.variants = master.variants.filter((variant) => {
-    if (!variant.resolution) {
-      return true;
+  if (session.resolution) {
+    try {
+      master.variants = filterByString(master.variants, session.resolution);
+    } catch {
+      throw new InvalidFilter();
     }
-    return variant.resolution.height <= session.maxResolution;
-  });
+  }
 
   const filePath = parseFilepath(url);
   for (const v of master.variants) {
@@ -64,12 +73,18 @@ export async function formatMediaPlaylist(session: Session, path: string) {
 
   rewriteSegmentUrls(media, url);
 
-  addInterstitials(media, session.interstitials, session.id);
+  if (session.interstitials) {
+    addInterstitials(media, session.interstitials, session.id);
+  }
 
   return hlsParser.stringify(media);
 }
 
 export async function formatAssetList(session: Session, timeOffset: number) {
+  if (!session.interstitials) {
+    throw new NoInterstitialsError();
+  }
+
   const interstitials = session.interstitials.filter(
     (ad) => ad.timeOffset === timeOffset,
   );

packages/stitcher/src/session.ts

@@ -3,8 +3,8 @@ import { randomUUID } from "crypto";
 import { extractInterstitialFromVmapAdbreak } from "./vast.js";
 import { getVmap } from "./vmap.js";
 import createError from "@fastify/error";
-import type { Session, Interstitial } from "./types.js";
 import { isAssetAvailable } from "./helpers.js";
+import type { Session, Interstitial } from "./types.js";
 
 const NoSessionError = createError<[string]>(
   "NO_SESSION",
@@ -30,46 +30,50 @@ export async function createSession(data: {
     url: string;
   };
   interstitials?: Interstitial[];
-  maxResolution?: number;
+  resolution?: string;
 }) {
   if (!(await isAssetAvailable(data.assetId))) {
     throw new PlaylistUnavailableError(data.assetId);
   }
 
   const sessionId = randomUUID();
 
-  const interstitials: Interstitial[] = [];
+  let interstitials: Interstitial[] | undefined;
 
   if (data.vmap) {
     const vmap = await getVmap(data.vmap.url);
 
     for (const adBreak of vmap.adBreaks) {
+      if (!interstitials) {
+        interstitials = [];
+      }
+
       interstitials.push(
         ...(await extractInterstitialFromVmapAdbreak(adBreak)),
       );
     }
   }
 
-  if (data.interstitials) {
-    interstitials.push(...data.interstitials);
-  }
+  if (data.interstitials?.length) {
+    if (!interstitials) {
+      interstitials = [];
+    }
 
-  let maxResolution = data.maxResolution;
-  if (!maxResolution) {
-    const MAX_RESOLUTION_8K = 4320;
-    maxResolution = MAX_RESOLUTION_8K;
+    interstitials.push(...data.interstitials);
   }
 
   const session = {
     id: sessionId,
     assetId: data.assetId,
     interstitials,
-    maxResolution,
+    resolution: data.resolution,
   } satisfies Session;
 
   const redisKey = getRedisKey(sessionId);
 
-  await client.json.set(redisKey, `$`, session);
+  const rawSession = JSON.parse(JSON.stringify(session));
+
+  await client.json.set(redisKey, `$`, rawSession);
   await client.expire(redisKey, 60 * 60 * 6);
 
   return session;

packages/stitcher/src/types.ts

@@ -1,8 +1,8 @@
 export type Session = {
   id: string;
   assetId: string;
-  interstitials: Interstitial[];
-  maxResolution: number;
+  interstitials?: Interstitial[];
+  resolution?: string;
 };
 
 export type InterstitialType = "ad" | "bumper";