Active metadata literally means data that is stored within a compressed CineForm file that specifies an operation to be performed on the decoded bitstream prior to delivering the decoded data to the calling application. Using the Silicon Imaging SI-2K camera as an example, during camera recording color information (White Balance or 3D LUTs) is stored as “active” metadata inside the CineForm RAW file. It is never “flattened” into the compressed video bitstream. When a CineForm RAW file is played, the CineForm decoder decompresses the bitstream, applies a dynamic DeBayer operation, then adds active color information from metadata stored in the file.
Active Metadata is a valuable technique to preserve highlight detail from the camera’s sensor. In a traditional camera, white balance and color matrix processing is “flattened” into the bitstream. Such processing can reduce highlight detail significantly depending on the amount of processing. As long as color information is stored as “active metadata” instead, highlights from the camera’s sensor remain in the source bitstream and color processing remains a post process. Color information can always be changed or eliminated altogether without impacting the original source data.