# FFmpeg documents r_frame_rate as a guessed least-common-multiple base rate, not the average (mixed 25/30 fps gives 150); avg_frame_rate is the average, and for MOV/MP4 the demuxer accumulates stts durations and frame counts for it (media duration, independent of edit...

- id: art_01M5NGWYB0Q0G9R5MGJY4855Y1
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T10, T13 · tags: none
- updated: 2026-10-23T23:17:53.114Z
- url: https://veyrul.com/articles/art_01M5NGWYB0Q0G9R5MGJY4855Y1

FFmpeg documents r_frame_rate as a guessed least-common-multiple base rate, not the average (mixed 25/30 fps gives 150); avg_frame_rate is the average, and for MOV/MP4 the demuxer accumulates stts durations and frame counts for it (media duration, independent of edit lists).

FFmpeg documents r_frame_rate as a guessed least-common-multiple base rate, not the average (mixed 25/30 fps gives 150); avg_frame_rate is the average, and for MOV/MP4 the demuxer accumulates stts durations and frame counts for it (media duration, independent of edit lists).

Curator qualifications: tb_unreliable heuristic, fallbacks, ffprobe exposure, DTS/PTS disagreement report and fps-filter defaults (F2-F9) not reinspected. Static reading only; no file probed.

Limitations: Static reading only; no file probed.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://github.com/ffmpeg/ffmpeg",
      "note": "cited at https://github.com/FFmpeg/FFmpeg; libavformat/avformat.h lines 895-904 at e2798d5c; doc/faq.texi lines 660-667; mov.c lines 3914-3921 (shared with CA-B022)"
    },
    {
      "url": "https://github.com/FFmpeg/FFmpeg",
      "note": "observed URL (dated/alias form of the cited catalogue source; canonical identity retained)"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] FFmpeg documents r_frame_rate as a guessed least-common-multiple base rate, not the average (mixed 25/30 fps gives 150); avg_frame_rate is the average, and for MOV/MP4 the demuxer accumulates stts durations and frame counts for it (media duration, independent of edit lists). · locator: cited at https://github.com/FFmpeg/FFmpeg; libavformat/avformat.h lines 895-904 at e2798d5c; doc/faq.texi lines 660-667; mov.c lines 3914-3921 (shared with CA-B022) · source: https://github.com/ffmpeg/ffmpeg

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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