snapshot of video in news reports？
ChatGPT回答：
Exactly — what you’re describing in news reports (those “glitchy” stills pulled from video) usually comes from these frame-level anomalies.
When a news outlet freezes a frame from a live feed, a compressed stream, or a surveillance camera, you often see distortions like:
Why Snapshots Look Distorted
- Compression Artifacts
- News footage is almost always compressed (H.264, HEVC, etc.) before broadcast.
- If the snapshot is taken from a P-frame or B-frame (which only store changes from earlier frames), it may lack full image data, so you get blockiness, smearing, or partial detail.
- Transmission Errors
- Live feeds (satellite, cellular, internet) can drop packets.
- Instead of losing the whole frame, the decoder “guesses” or repeats partial data, which looks like scrambled squares or horizontal tearing when frozen.
- Interlacing or Frame Mixing
- Many cameras (especially older broadcast ones) capture in interlaced mode.
- A single snapshot may contain fields from two different points in time, so moving objects look jagged or duplicated.
- Rolling Shutter or Motion
- If the subject is moving quickly and the snapshot isn’t from a full progressive I-frame, motion can look warped or “melted.”
Why It’s More Noticeable in News Stills
- News editors often grab a frame quickly for illustration, without cleaning it up.
- Live or low-bandwidth feeds (e.g., war zone reporting, CCTV) have more errors than polished studio video.
- Stills exaggerate the artifact: in motion, the eye may not notice brief glitches, but when frozen, they become obvious.
So yes — the distortions in snapshots from video are usually not because of deliberate editing, but because of frame-level anomalies from compression, transmission, or capture that get exposed when you freeze the video.
