[FFmpeg-user] Accurate seek times with multiple input files

[Mountain Man]

Thank you Carl.


> Unrelated:
> I don't think -r 29.97 is correct if frame accuracy
> is needed.


I don't recall which program I had an issue with but years ago I had
problems with a program creating a video DVD when the framerate was 30.
Someone pointed out that the NTSC standard was actually 29.97 and that
fixed my problem.  I've never given it any further thought since then.

Sorry if I missed something, but does -ss really
> support a stream identifier? I searched on
> http://ffmpeg.org/ffmpeg-all.html#Main-options but
> did not find any indication.
>

I'm afraid this is the answer to my question, unless there is a way to
order the arguments in such a way that -ss comes after -i *and* ffmpeg
still can tell which input it refers to.  If there isn't I can pull out the
video stream first and then combine it with the audio in a second step but
that takes a bit more time.  However, if the video segment created turns
out to be slightly longer or shorter than expected (due to different input
frame rates) the script needs to re process the audio and recombine them
anyway so this won't always involve extra time.

Are you searching for the -itsoffset option?


No, I'm pretty sure that isn't what I'm looking for.  I'm trying to create
a file with video and audio streams which both start and end at the same
time.  I was trying to use a stream identifier with -ss but as you point
out the documentation shows this isn't supported.

Thanks again for your help.


On Fri, Jun 14, 2013 at 3:27 AM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> Mountain Man <txmountainman45 <at> gmail.com> writes:
>
> > Unfortunately I haven't been able to figure out how
> > to make this work if I use -ss after the input file
> > (more accurate).  For example, this command works
> > as expected:
> >
> > ffmpeg  -ss 4 -i 100_0290.MOV -i threesec.wav
> > -map 0:v -map 1:a -t 3.003 -acodec copy -vcodec ffv1
> > -pix_fmt yuv420p -r 29.97  combined.avi
>
> Unrelated:
> I don't think -r 29.97 is correct if frame accuracy
> is needed.
>
> > I tried:
> >
> > ffmpeg   -i 100_0290.MOV -i threesec.wav -map 0:v
> > -map 1:a -ss:0 4 -ss:1 0 -t 3.003 -acodec copy
> > -vcodec ffv1 -pix_fmt yuv420p -r 29.97  combined.avi
>
> Sorry if I missed something, but does -ss really
> support a stream identifier? I searched on
> http://ffmpeg.org/ffmpeg-all.html#Main-options but
> did not find any indication.
> Are you searching for the -itsoffset option?
>
> Carl Eugen
>
> _______________________________________________
> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>