P-frame (predictive frame)
Definition
A frame encoded as a set of changes relative to a preceding reference frame. P-frames are smaller than I-frames because they only store differences. An unexpected burst of large P-frames or a prediction error at a join point is a signature of editing.
Related terms
- Bitrate anomaly
- A departure from the expected relationship between scene complexity and compressed file size. Sudden drops, plateaux, or spikes in the per-second bitrate...
- Double compression
- The artefact introduced when a video that has already been compressed is re-compressed. Each compression cycle degrades quality and leaves statistical signatures...
- Hash verification
- Calculating a cryptographic hash (MD5 or SHA-256) of a file and comparing it to a previously recorded reference value. If the hashes...
- I-frame (intra-coded frame)
- A video frame that is encoded entirely from its own pixel data, without reference to any other frame. I-frames mark the start...
- Re-recording artefact
- A visual or statistical signature introduced by pointing a camera at a screen playing back footage. Includes moiré patterns, screen reflections, temporal...
Explained in
- Video Authentication and Integrity VerificationA frame encoded as a set of changes relative to a preceding reference frame. P-frames are smaller than I-frames because they only store differences. An unexpec...