Why does FFMPEG report the wrong duration?

Question

I have an oldish build of FFmpeg that I can't easily change.

We use FFmpeg to find the duration of video and sound files. So far it has been working wonderfully.

Recently on an uploaded file, FFmpeg has reported a 30 second file as being 5 minutes 30 seconds in length.

Could it be something wrong with the file rather than FFmpeg?

If I use FFmpeg to convert to another file, the duration is restored.

In case it matters, ffmpeg -i 'path to the file' produces:

FFmpeg version Sherpya-r15618, Copyright (c) 2000-2008 Fabrice Bellard, et al.
  libavutil     49.11. 0 / 49.11. 0
  libavcodec    52. 0. 0 / 52. 0. 0
  libavformat   52.22. 1 / 52.22. 1
  libavdevice   52. 1. 0 / 52. 1. 0
  libswscale     0. 6. 1 /  0. 6. 1
  libpostproc   51. 2. 0 / 51. 2. 0
  built on Oct 14 2008 23:43:47, gcc: 4.2.5 20080919 (prerelease) [Sherpya]
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'H:\path\to\file.mov':
  Duration: 00:05:35.00, start: 0.000000, bitrate: 1223 kb/s
    Stream #0.0(eng): Audio: aac, 44100 Hz, stereo, s16
    Stream #0.1(eng): Video: h264, yuv420p, 720x576, 25.00 tb(r)
Must supply at least one output file

It's that very command I use to then extract the duration with RegEx.

Does anyone have a nice application that can do what I'm trying above but get it right 100% of the time?

Answer 1

Check it with a newer version of ffmpeg (you don't have to replace your build), and if it gives the same duration you can probably blame the file.

Answer 2

You should not rely on the stderr.

The stderr output is not intended to be machine parsed: it is for informational purposes only and prone to breakage.

Parse it with

ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 input.mp4
30.024000

You can also use ffmpeg to get the duration by fully decoding the file.

ffmpeg -i input.webm -f null -
...
frame=206723 fps=1390 q=-0.0 Lsize=N/A time=00:57:28.87 bitrate=N/A speed=23.2x

For detail refer to Format (container) duration

Answer 3

You can try tcprobe, part of transcode pack.