With the increasing number of digital transmissions, there is an opportunity to utilize existing broadcast channels to send hidden video transmissions. This presentation outlines and demonstrates a technique to insert a hidden video channel within a larger standard video feed, or "hide in plain sight". The approach outlined consists of three parts: data (or video) insertion, data security, and data recovery. These three components are essential to complete a secured digital transmission. To insert the data, knowledge of the standard (for example, MPEG 1, 2, or 4) is used to place the information to be hidden into the compressed data stream post quantization. Since the encoder has perfect knowledge of the receiver's model, it is possible to place the data in the compressed data in a manner that is visually un-intrusive. The technique to hide the data will be presented and an example given. Since, the data (or video) to be inserted may be of a sensitive nature, it is necessary to provide a level of security, which will render the video stream useless if its presence is detected. Both, spatial and temporal dispersion are used to reduce the likelihood of detection with the addition of a modulation of the signal to reduce the image to noise unless the key is known. The intended viewer of the embedded data (or video stream), with knowledge of the key, recovers the data by encoding the incoming video stream with the appropriate standard, and extracting the data prior to quantization. While the work in this paper focuses on the insertion of hidden video into a broadcast signal the same technique serves to prevent tampering to the broadcast signal, since modification of the image data will corrupt the hidden signal. In this way, this provides a level of tamper protection/detection for video, which may be used in legal proceedings.
