Add fps option

Author: andycloke

README.md

@@ -47,6 +47,7 @@ The video will be saved at the specified `savePath` (`/tmp/video.mp4` in the abo
 - `savePath` <[string]> Where to save the video.
 - `options` <[Object]>
   - `followPopups` <[boolean]> Whether or not to follow browser focus when popups are opened. Defaults to `false`. Note: this option will only work correctly if the popups opened are the same size as the original page. If a smaller or larger popup is open, frames will be scaled to fit the original size.
+  - `fps` <[number]> The frames per second for the recording. Defaults to `25`. A higher number will improve the recording quality but also increase the file size.
 - returns: <[Promise]<[PageVideoCapture](#class-pagevideocapture)>>
 
 Records video of a page and saves it at the specified path.

src/PageVideoCapture.ts

@@ -11,6 +11,7 @@ const debug = Debug('pw-video:PageVideoCapture');
 
 export interface CaptureOptions {
   followPopups: boolean;
+  fps?: number;
 }
 
 interface ConstructorArgs {
@@ -36,7 +37,7 @@ export class PageVideoCapture {
 
     const collector = await ScreencastFrameCollector.create(page, options);
     const queue = new SortedFrameQueue();
-    const writer = await VideoWriter.create(savePath);
+    const writer = await VideoWriter.create(savePath, options);
 
     const capture = new PageVideoCapture({ collector, queue, page, writer });
     await collector.start();

src/VideoWriter.ts

@@ -5,14 +5,18 @@ import { ensureDir } from 'fs-extra';
 import { dirname } from 'path';
 import { PassThrough } from 'stream';
 import { ensureFfmpegPath } from './utils';
+import { CaptureOptions } from './PageVideoCapture';
 
 const debug = Debug('pw-video:VideoWriter');
 
 export class VideoWriter extends EventEmitter {
-  public static async create(savePath: string): Promise<VideoWriter> {
+  public static async create(
+    savePath: string,
+    options?: CaptureOptions,
+  ): Promise<VideoWriter> {
     await ensureDir(dirname(savePath));
 
-    return new VideoWriter(savePath);
+    return new VideoWriter(savePath, options);
   }
 
   private _endedPromise: Promise<void>;
@@ -21,10 +25,13 @@ export class VideoWriter extends EventEmitter {
   private _stopped = false;
   private _stream: PassThrough = new PassThrough();
 
-  protected constructor(savePath: string) {
+  protected constructor(savePath: string, options?: CaptureOptions) {
     super();
 
     ensureFfmpegPath();
+    if (options && options.fps) {
+      this._framesPerSecond = options.fps;
+    }
     this._writeVideo(savePath);
   }