What are best practices for using short (3-4 minute) videos for extraction?

It is possible to have successful extractions even with a short (3-4 minutes) video, if the following best practices are observed:

Watermarking parameters

Watermarking strength: at least 100

Capture parameters

Capture method: Screen-grabbing app or HDMI
Resolution: Full HD or higher
Codec: H.264 Main Profile or HEVC
Codec compression rate: CRF 22 or lower
Bitrate: 5/6 Mbps or higher

What are the recommended options for capturing video for a successful extraction?

In addition to what is stated in the previous FAQ, there are many parameters that can be tweaked to maximize the chance of a successful extraction:

Video length

The watermark affects individual video frames very slightly, and thus the watermark appears invisible for video viewer. In order to make watermark visible and to be able to extract it, the video sample needs to be sufficiently long.

Minimum length of video sample depends on various factors, including watermark strength, picture quality of video sample file and video content. In the most cases, sufficient video sample length can be determined based on this table:

Watermark Strength	Picture Quality	Video Sample Minimum Length
70-100	Excellent	5 minutes
50-100	Good or excellent	10 minutes
50-100	Poor or better	15 minutes
35	Average or better	15 minutes

Recording the video clip

There are several possible recording methods:

Software or hardware-based recording device (HDMI capture or screen grabbing)
Camcorder to record the screen
The camera function of a mobile phone

The recording devices generally provide highest quality video, therefore allowing the fastest extraction. On the other hand, if a camcorder or mobile phone is used, the video sample file needs to be slightly longer.

The next sections detail dos and don’ts of video sample file capturing. The files created following the instructions allow faster extraction.

General guidance for capturing video clip with a recording device or screen-grabbing software

DOS	DONTS
☑ Record for a long time, typically 5-15 minutes.	ⓧ Avoid using UltraHD resolution UltraHD resolution video often creates large files which are slow to process.
☑ Use high resolution, such as FullHD (1920x1080) or 720p.	ⓧ Create very large (long) files. If the video sample file is larger than 5 GB it cannot be submitted to Reveal.
☑ Ensure the recording device does not leave out any part of the video content. Try to configure the recording device to record entire video.
☑ Use aspect ratio matching the video content for recording, such as 16:9.
☑ Do not unnecessarily re-encode video. You only need to re-encode video if the file is larger than 5 GB.

Additional guidance for capturing video clip with a recording camcorder or camera device

DOS	DONTS
☑ Record for a long time, typically 5-15 minutes.	ⓧ Record partial screen. Keep entire content of the display to be recorded visible on the video at all times.
☑ Use high resolution, such as FullHD (1920x1080) or 720p.	ⓧ Use portrait orientation when recording the screen.
☑ The camcorder or camera must be horizontal, perpendicular to the screen and pointed to the screen center.	ⓧ Have multiple screens simultaneously visible on recording.
☑ Use aspect ratio matching the video content for recording, such as 16:9.	ⓧ have reflections on screen due to daylight or powerful lamps.
☑ To avoid motion noise, you should place the camcorder on a tripod or other stand.	ⓧ Pointing at screen with an angle.
☑ The content of video should fill at least fourth of the video screen or more. In case video is too small, use zoom to increase its size.	ⓧ Record distorted image (e.g. using curved lens (fisheye) or too large zoom).
	ⓧ Use very small resolution (e.g. 640x480).