An interval is different from a frame rate
A one-second extraction interval asks for a picture at successive times: zero seconds, one second, two seconds, and so on. A 30 FPS source contains around 30 frames during each of those seconds. You are selecting representatives, not exporting the full sequence.
The preferred Mediabunny path selects a decoded frame near the requested time and records its presentation timestamp. On a variable-frame-rate recording, frame durations are uneven, so those timestamps may not be neat multiples of one second. Compatible preview mode records approximate browser seek times instead; check the workspace notice before relying on timing.
Set up an interval extraction
- Open Extract frames and choose Try Pro with samples. This example uses the supplied videos.
- Select By interval and enter 1 second under Capture every.
- Set the range. For example, select a short section rather than an entire hour-long recording.
- Review the per-video estimate, then select Extract 2 videos to process the supplied sample queue.
- Select the pictures you need and export them as images or a ZIP.
Pick the spacing that fits the task
One second can work well for a short demonstration or an evolving scene. It may miss a very quick action. Use a shorter interval for that small portion of the video, or use Capture a frame to choose an exact moment.
For a static interview or lecture, a longer interval may produce a more manageable overview. If your goal is simply to see the overall content, a fixed count is often easier: choose twelve or twenty-four images, then compare the result.
When you need a command-line workflow
FFmpeg can perform the same type of time sampling locally on a desktop. The example below writes approximately one JPG per second. Run it in a folder where the output files will be easy to find.
ffmpeg -i input.mp4 -vf fps=1 frame_%04d.jpg