[FFmpeg-user] Concat 2 videos, results in wrong length of the result

[Nitish Prabhu]

On Sat, Sep 9, 2017 at 10:24 AM, Gyan <gyandoshi at gmail.com> wrote:
>
> Run this on 96.out.mp4
>
>     ffmpeg -i 96.out.mp4 -c copy -video_track_timescale 12800 96.new.mp4
>
> and concat this with the other file.

Won't altering the timebase for "96.out.mp4" make the "96.new.mp4" play
slower than it was recorded at?

Is it better to instead drop the frames in "96.out.mp4" (which has a frame
rate of 29.97fps) and make it 25fps (frame rate of 98.out.mp4), and then
concatenate the streams?

Otherwise, we can also use the concat filter
<https://trac.ffmpeg.org/wiki/Concatenate#filter> (present on recent ffmepg
versions) to generate a variable frame rate concatenated output (with all
frames intact).