Opened 8 years ago

Closed 8 years ago

#5160 closed enhancement (fixed)

Document how -fs reduces size

Reported by: Dan Jacobson Owned by:
Priority: wish Component: documentation
Version: git-master Keywords:
Cc: Blocked By:
Blocking: Reproduced by developer: yes
Analyzed by developer: yes


How to reproduce:
On the man page, and in /usr/share/doc/ffmpeg-doc/manual/ffmpeg.html we see:

       -fs limit_size (output)
           Set the file size limit, expressed in bytes.

Mention how it does this: reduced screen size? Reduced bitrate? Or just
plain chopping of the movie when the limit is reached?

Change History (2)

comment:1 by Misaki, 8 years ago

It appears to stop, similar to pressing ctrl-C in Linux, once detected size exceeds the option. It finishes encoding the remaining frames. So, using -tune zerolatency for h264 makes it more accurate, while having a high bitrate/low crf makes it exceed the size.

comment:2 by Stefano Sabatini, 8 years ago

Analyzed by developer: set
Reproduced by developer: set
Resolution: fixed
Status: newclosed

Fixed in:

commit 9effa012553167d3662f1392310671c575c9322f
Author: Umair Khan <>
Date:   Mon Feb 1 01:17:58 2016 +0530

    doc/ffmpeg: explain properly how -fs works
    Fix trac ticket #5160.
    Signed-off-by: Umair Khan <>
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