[FFmpeg-user] writing to multiple outputs causes extra messages?

[Roger Pack]

> Stream mapping:
>   Stream #0:0 (mpeg2video) -> scale (graph 0)
>   Stream #1:0 (rawvideo) -> overlay:overlay (graph 0)
>   overlay (graph 0) -> Stream #0:0 (mpeg1video)
>   Stream #0:0 -> #1:0 (mpeg2video -> mpeg4)
>   Stream #0:1 -> #1:1 (ac3 -> libmp3lame)
> Press [q] to stop, [?] for help
> [Parsed_overlay_1 @ 03a60c20] Buffer queue overflow, dropping.
>     Last message repeated 27 times

My guess is that it's passing frames from the first input 'straight'
to the second output, which leaves none for the overlay filter to use.
 Seems a bit odd...