[FFmpeg-trac] #3856(ffmpeg:new): Incorrect frame rate for webm (vp8, libvpx)

FFmpeg trac at avcodec.org
Fri Aug 15 06:36:35 CEST 2014

#3856: Incorrect frame rate for webm (vp8, libvpx)
             Reporter:  lespaul75  |                     Type:  defect
               Status:  new        |                 Priority:  normal
            Component:  ffmpeg     |                  Version:  unspecified
             Keywords:             |               Blocked By:
             Blocking:             |  Reproduced by developer:  0
Analyzed by developer:  0          |
 Summary of the bug:
 Output rate option (-r) is ignored and rate is forced to 25 fps.

 How to reproduce:
 1) Create a directory with 120 JPG images.
 2) Encode to webm with command:
 ffmpeg -f image2 -start_number 0012910 -i "G%07d.JPG" -vf
 "crop=1778:1000:250:0, scale=1280x720" -r 60 -crf 16 -b:v 60M -an tst.webm

 Output file should be exactly 2 seconds.  Instead, it is 4.78 seconds,
 giving a calculated frame rate of 25 fps.

 However, the output of FFmpeg claims to be producing 60 fps, even though
 the total time displayed is clearly 4.78 seconds.

 Further, playback in both FFplay and MPC-HC is at 25 fps.  Oddly, opening
 the "properties" window of MPC-HC displays "60 fps" even while playing at
 25 fps.

 FFmpeg version is reported as: N-64757-g277e5ca (not sure how this
 correlates to 2.xxx version number)

 Workaround:  Specifying the "-r 60" option on both the input and output
 does correctly set the rate to 60 fps.

Ticket URL: <https://trac.ffmpeg.org/ticket/3856>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker

More information about the FFmpeg-trac mailing list