Presentation Timestamp (PTS)
Definition
A value stored in the container for each packet indicating when that frame should be displayed. In an unmodified recording, PTS values increase monotonically at the camera's frame rate. A deleted frame leaves a gap; an inserted frame disrupts the expected interval.
- Stored in
- The video container, per packet
- Function
- Marks when a frame should be displayed
- Unmodified pattern
- Increases monotonically at frame rate
- Tamper signature
- Gap on deletion, disruption on insertion
Common questions
Why can PTS analysis detect frame deletion when the video plays back smoothly?+
Re-encoding after editing can smooth playback timing so the video looks continuous to the eye, but the underlying PTS sequence in the container often retains an irregular interval or a jump at the edit point, which frame-by-frame timestamp extraction can reveal even when visual inspection cannot.
Does an intact, monotonic PTS sequence prove a video is unedited?+
Not conclusively. A sophisticated edit can be followed by a full re-encode that regenerates clean, evenly spaced timestamps, so PTS analysis is one indicator among several, such as container metadata, compression artefacts, and frame content, used together to assess authenticity.
Related terms
- Group of Pictures (GOP)
- The periodic structure of I-frames, P-frames, and B-frames in a compressed video stream. Each encoding generation imposes its own GOP structure. When...
- 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...
- Inter-Frame Residual
- The pixel-level difference between a predicted frame and the actual frame after decoding. In unmodified video, residuals at scene cuts are elevated...
- Motion Vector Consistency
- In unmodified video, motion vectors across consecutive frames track the same objects and follow smooth trajectories. A deleted or inserted frame breaks...
- P-Frame (Predictive Frame)
- A frame encoded as a set of changes relative to a preceding reference frame. P-frames are smaller than I-frames because they only...