Invisible or forensic watermarking is the process of embedding identifiable information within each individual copy of a video file. A forensic watermark is essentially a code or a set of characters embedded into the digital document, video, audio, image, or program which enables the unique identification of the content creator and its authorized user. A good forensic watermark should be completely imperceptible, be able to store a large payload, and impossible to remove without damaging the host video. It should also be secure, i.e., it cannot be modified or faked. With exponential growth in the production and consumption of digital and OTT content, forensic watermarking has become ubiquitous in the digital rights management (DRM) industry. Given below are some applications of the digital watermarking technology:
- Audience Monitoring: In Europe and the USA, the audio on TV channels are embedded with the encoded channel names. A device at the viewer’s home then captures the sound, decodes the message, and sends them to the monitoring companies for measuring the audience and market share.
- Pre-Release: When pre-release content is distributed to external stakeholders of the studio, a static watermark is applied to them to prevent unauthorized usage.
- Digital Cinema: Movie theaters apply theater and screen time information as digital watermark to cinema in order to identify and track illegal recording. The embedded message is usually the date of projection and the beamer ID.
- OTT-VOD Service: Digital watermarks have their widest usage for DRM video protection on OTT platforms such as Netflix, Amazon Prime, Hotstar, Hulu, etc., where a subscriber mark is added to the DRM protected content to track users in case of illegal usage
- OTT Live Service: Live/linear content such as real time sports are also applied with the subscriber mark.
In visible video watermarking, on the other hand, the video bitstream is manipulated in such a way that a visible logo or watermark can be seen in it. However, care should be taken that visible watermarks are non-intrusive so as not to hamper the viewing experience. Visible watermarks help prevent web-scraping and provide protection against unauthorized usage of the video asset. In contrast to forensic watermarking, visible watermarking can also be used to specify ownership of the video and embed a subtle branding of the content creators/distributors during playback.