diff --git a/desktop/src/main/stream.ts b/desktop/src/main/stream.ts
index b5d497d053..1e2ae44013 100644
--- a/desktop/src/main/stream.ts
+++ b/desktop/src/main/stream.ts
@@ -246,7 +246,7 @@ const handleConvertToMP4Write = async (request: Request) => {
 
     const token = randomUUID();
     pendingVideoResults.set(token, outputTempFilePath);
-    return new Response(JSON.stringify([token]), { status: 200 });
+    return new Response(token, { status: 200 });
 };
 
 const handleVideoRead = async (token: string) => {
@@ -277,17 +277,17 @@ const handleVideoDone = async (token: string) => {
  * The difference here is that we the conversion generates two streams - one for
  * the HLS playlist itself, and one for the file containing the encrypted and
  * transcoded video chunks. So instead of returning a single token, we return a
- * JSON array containing two tokens so that the renderer can read them off
- * separately.
+ * JSON object containing two tokens (aand other metadata) so that the renderer
+ * can read them off separately.
  */
 const handleGenerateHLSWrite = async (request: Request) => {
     const inputTempFilePath = await makeTempFilePath();
     await writeStream(inputTempFilePath, request.body!);
 
     const outputFilePathPrefix = await makeTempFilePath();
-    let paths: FFmpegGenerateHLSPlaylistAndSegmentsResult;
+    let result: FFmpegGenerateHLSPlaylistAndSegmentsResult;
     try {
-        paths = await ffmpegGenerateHLSPlaylistAndSegments(
+        result = await ffmpegGenerateHLSPlaylistAndSegments(
             inputTempFilePath,
             outputFilePathPrefix,
         );
@@ -297,9 +297,12 @@ const handleGenerateHLSWrite = async (request: Request) => {
 
     const playlistToken = randomUUID();
     const videoToken = randomUUID();
-    pendingVideoResults.set(playlistToken, paths.playlistPath);
-    pendingVideoResults.set(videoToken, paths.videoPath);
-    return new Response(JSON.stringify([playlistToken, videoToken]), {
-        status: 200,
-    });
+    pendingVideoResults.set(playlistToken, result.playlistPath);
+    pendingVideoResults.set(videoToken, result.videoPath);
+
+    const { dimensions } = result;
+    return new Response(
+        JSON.stringify({ playlistToken, videoToken, dimensions }),
+        { status: 200 },
+    );
 };
diff --git a/web/packages/gallery/services/ffmpeg/index.ts b/web/packages/gallery/services/ffmpeg/index.ts
index 3f69fdc520..7d67a37e44 100644
--- a/web/packages/gallery/services/ffmpeg/index.ts
+++ b/web/packages/gallery/services/ffmpeg/index.ts
@@ -266,8 +266,8 @@ export const convertToMP4 = async (blob: Blob): Promise<Blob | Uint8Array> => {
 };
 
 const convertToMP4Native = async (electron: Electron, blob: Blob) => {
-    const tokens = await writeVideoStream(electron, "convert-to-mp4", blob);
-    const token = tokens[0]!;
+    const res = await writeVideoStream(electron, "convert-to-mp4", blob);
+    const token = await res.text();
     const mp4Blob = await readVideoStream(electron, token).then((res) =>
         res.blob(),
     );
diff --git a/web/packages/gallery/services/video.ts b/web/packages/gallery/services/video.ts
index 1f6f377837..aa2c1bd119 100644
--- a/web/packages/gallery/services/video.ts
+++ b/web/packages/gallery/services/video.ts
@@ -13,6 +13,7 @@ import { gunzip, gzip } from "ente-new/photos/utils/gzip";
 import { ensurePrecondition } from "ente-utils/ensure";
 import { z } from "zod";
 import {
+    GenerateHLSResult,
     readVideoStream,
     videoStreamDone,
     writeVideoStream,
@@ -399,11 +400,13 @@ const processQueueItem = async (
 ) => {
     log.debug(() => ["gen-hls", { file, uploadItem }]);
 
+    // TODO(HLS):
     const fileBlob = await fetchOriginalVideoBlob(file, uploadItem);
 
-    // TODO(HLS):
-    const tokens = await writeVideoStream(electron, "generate-hls", fileBlob!);
-    const [playlistToken, videoToken] = [tokens[0]!, tokens[1]!];
+    const res = await writeVideoStream(electron, "generate-hls", fileBlob!);
+    const { playlistToken, videoToken, dimensions } = GenerateHLSResult.parse(
+        await res.json(),
+    );
 
     try {
         const playlistBlob = await readVideoStream(
@@ -431,10 +434,7 @@ const processQueueItem = async (
         const playlistData = await encodePlaylistJSON({
             type: "hls_video",
             playlist: await playlistBlob.text(),
-            // TODO(HLS): Critical, fix this before any use.
-            width: 1280,
-            // TODO(HLS): Critical, fix this before any use.
-            height: 720,
+            ...dimensions,
             size: objectSize,
         });
 
diff --git a/web/packages/gallery/utils/native-stream.ts b/web/packages/gallery/utils/native-stream.ts
index 50934e5afa..9c67d3afc4 100644
--- a/web/packages/gallery/utils/native-stream.ts
+++ b/web/packages/gallery/utils/native-stream.ts
@@ -128,6 +128,27 @@ export const writeStream = async (
  */
 type VideoStreamOp = "convert-to-mp4" | "generate-hls";
 
+/**
+ * The contents of the {@link Response} body returned by
+ * {@link writeVideoStream} for op "generate-hls".
+ */
+export const GenerateHLSResult = z.object({
+    /**
+     * A token that can be used to passed to {@link readVideoStream} to retrieve
+     * the generated HLS playlist.
+     */
+    playlistToken: z.string(),
+    /**
+     * A token that can be used to passed to {@link readVideoStream} to retrieve
+     * the video segments.
+     */
+    videoToken: z.string(),
+    /**
+     * The dimensions (width and height in pixels) of the generated video stream.
+     */
+    dimensions: z.object({ width: z.number(), height: z.number() }),
+});
+
 /**
  * Variant of {@link writeStream} tailored for video processing operations.
  *
@@ -138,22 +159,23 @@ type VideoStreamOp = "convert-to-mp4" | "generate-hls";
  * @param video The video to convert, as a {@link Blob} or a
  * {@link ReadableStream}.
  *
- * @returns an array of token that can then be passed to {@link readVideoStream}
- * to read back the processed video. The count (and semantics) of the tokens are
+ * @returns the successful (2xx) HTTP response received from the node side (An
+ * exception is thrown otherwise). The contents of the response body are
  * dependent on the operation:
  *
- * - "convert-to-mp4" returns a single token (which can be used to retrieve the
- *   converted MP4 file).
+ * - "convert-to-mp4" returns a plain string which is a token that can then be
+ *   passed to {@link readVideoStream} to retrieve the converted MP4 file.
  *
  * - "generate-hls" returns two tokens, first one that can be used to retrieve
  *   the generated HLS playlist, and the second one that can be used to retrieve
- *   the video (segments).
+ *   the video (segments). It also returns the dimensions of the generated
+ *   video. See {@link GenerateHLSResult}.
  */
 export const writeVideoStream = async (
     _: Electron,
     op: VideoStreamOp,
     video: Blob | ReadableStream,
-): Promise<string[]> => {
+): Promise<Response> => {
     const url = `stream://video?op=${op}`;
 
     const req = new Request(url, {
@@ -169,7 +191,7 @@ export const writeVideoStream = async (
     if (!res.ok)
         throw new Error(`Failed to write stream to ${url}: HTTP ${res.status}`);
 
-    return z.array(z.string()).parse(await res.json());
+    return res;
 };
 
 /**