[FFmpeg-user] Overlay Filter: eval n value

[Stefano Sabatini]

On date Wednesday 2013-06-26 20:44:25 -0400, Joshua Ostrom wrote:
> Thanks, the -loglevel debug gives some clues:
> 
> Stream mapping:
>   Stream #0:0 (h264) -> overlay:main (graph 0)
>   Stream #1:0 (png) -> overlay:overlay (graph 0)
>   overlay (graph 0) -> Stream #0:0 (libx264)
>   Stream #0:1 -> #0:1 (aac -> libfaac)
> Press [q] to stop, [?] for help
> [aac @ 0x2a13360] skip whole frame, skip left: 0
> [Parsed_overlay_0 @ 0x2a27860] Copying data in avfilter.
> frame=    0 fps=0.0 q=0.0 size=       0kB time=00:00:04.73 bitrate=   0.1kbits/s    
> frame=    0 fps=0.0 q=0.0 size=       0kB time=00:00:04.73 bitrate=   0.1kbits/s    
> n:1.000000 t:4.343975 pos:22723.000000 x:0.000000 xi:0 y:0.000000 yi:0

This means that the first frame has time 4.4. Check also the showinfo
output.

[...]
> So frame 1 (n:1.000000 )  is already at t:4.343975 seconds if I"m reading that correctly.  I assume that's related to the 55 dup message nearby.
> 
> If I enable the overlay I *have* to use a value greater than 4.3
> 
> No overlay shown at all
> -filter_complex overlay=enable='between(t\,1\,4.3)' \
> 
> Overlay shown for the first 4.4 seconds then removed
> -filter_complex overlay=enable='between(t\,1\,4.4)' \
> 

> Is there anyway to process (ffmpeg options etc) this so that I can
> either move the graphic or just disable (I prefer move as it looks a
> little more appealing) *before* that 4.4 second mark?

You have to fix your file timestamps, for example by shifting them so
that the video starts from 0, check setpts filter.

[...]