[Libav-user] Empty .MTS output videos when using -ss command line argument

[Alex Cohn]

On Mon, Apr 16, 2012 at 7:05 PM, Simon Daniels <simondaniels23 at gmail.com> wrote:
> Hi guys,
>
> I have a set of .MTS files that I'm trying to splice. If I start at 0:00:00,
> the output video works fine. But if I start splicing any time after 0:00:00,
> the output video is empty. I've used the exact same command line with other
> .MTS files and had no problem. It seems like something specific to this
> Panasonic Lumix camera. MP4 and MOV files work fine too.
>
> This repros in FFmpeg HEAD-8dfb13e, 0.10.2, and 0.8.3.
>
> Any ideas? Thanks!
>
> Users-MacBook-Pro:ffmpeg-0.10.2 user$ ./ffmpeg -ss 00:00:01 -t 00:00:25 -i
> 00004.MTS -threads 3 -acodec copy -vcodec copy "output.MTS"

Your input video stream has only one keyframe, which is the first
frame. For h264, -vcodec copy can only start writing video from a
keyframe. That's why it produces 0 frames in the end.

BR,
Alex Cohn