puppeteer-capture

A Puppeteer plugin for capturing page as a video with ultimate quality.
This project is brought to you by Alexey Pelykh.
Under The Hood
HeadlessExperimental
is used to
capture frames in a deterministic way. This approach allows to achieve better quality than using screencast.
Getting Started
const { capture, launch } = require('puppeteer-capture')
(async () => {
const browser = await launch()
const page = await browser.newPage()
const recorder = await capture(page)
await page.goto('https://google.com', {
waitUntil: 'networkidle0',
})
await recorder.start('capture.mp4')
await recorder.waitForTimeout(1000)
await recorder.stop()
await recorder.detach()
await browser.close()
})()
Time flow
The browser is running in a deterministic mode, thus the time flow is not real time. To wait for a certain amount of
time within the page's timeline, PuppeteerCapture.waitForTimeout()
must be used:
await recorder.waitForTimeout(1000)
Known Issues
--headless=new
is not supported
Sadly, it is so. For Puppeteer v23+, the plugin enforces use
of the chrome-headless-shell
binary.
Bad Chrome versions
117.0.5938.88
(default for puppeteer
version(s) 21.3.0
): reacts with targetCrashed
117.0.5938.92
(default for puppeteer
version(s) 21.3.2
…21.3.6
): reacts with targetCrashed
117.0.5938.149
(default for puppeteer
version(s) 21.3.7
…21.3.8
): reacts with targetCrashed
118.0.5993.70
(default for puppeteer
version(s) 21.4.0
…21.4.1
): reacts with targetCrashed
119.0.6045.105
(default for puppeteer
version(s) 21.5.0
…21.7.0
): reacts with targetCrashed
120.0.6099.109
(default for puppeteer
version(s) 21.8.0
): reacts with targetCrashed
MacOS is not supported
Unfortunately, it is so.
No capturing == Nothing happens
This relates to timers, animations, clicks, etc. To process interaction with the page, frame requests have to be
submitted and thus capturing have to be active.
Setting defaultViewport
causes rendering to freeze
The exact origin of the issue is not yet known, yet it's likely to be related to the deterministic mode.
Calling page.setViewport()
before starting the capture behaves the same, yet calling it after starting the capture
works yet not always. Thus it's safe to assume that there's some sort of race condition, since adding
recorder.waitForTimeout(100)
just before setting the viewport workarounds the issue.
Also it should be taken into account that since frame size is going to change over the time of the recording, frame size
autodetection will fail. To workaround this issue, frame size have to be specified:
const recorder = await capture(page, {
size: `${viewportWidth}x${viewportHeight}`,
})
await recorder.start('capture.mp4', { waitForFirstFrame: false })
await recorder.waitForTimeout(100)
await page.setViewport({
width: viewportWidth,
height: viewportHeight,
deviceScaleFactor: 1.0,
})
A friendlier workaround is enabled by default: recorder.start()
automatically waits for the first frame to be
captured. This approach seems to allow bypassing the alleged race condition:
const recorder = await capture(page, {
size: `${viewportWidth}x${viewportHeight}`,
})
await recorder.start('capture.mp4')
await page.setViewport({
width: viewportWidth,
height: viewportHeight,
deviceScaleFactor: 1.0,
})
Multiple start()
/stop()
fail
It's unclear why, yet after disabling and re-enabling the capture, callbacks from browser stop arriving.
Time-related functions are affected
The following functions have to be overriden with injected versions:
setTimeout
& clearTimeout
setInterval
& clearInterval
requestAnimationFrame
& cancelAnimationFrame
Date()
& Date.now()
performance.now()
The injection should happen before page content loads:
const recorder = await capture(page)
await page.goto('https://google.com')
Events
PuppeteerCapture
supports following events:
captureStarted
: capture was successfully started
frameCaptured
: frame was captured
frameCaptureFailed
: frame capture failed
frameRecorded
: frame has been submitted to ffmpeg
captureStopped
: capture was stopped
Dependencies
ffmpeg
It is resolved in the following order:
FFMPEG
environment variable, should point to the executable
- The executable that's available via the
PATH
environment variable
- Via
@ffmpeg-installer/ffmpeg
, if it's installed as dependency