[FFmpeg-user] Creating an advanced filter effect that repeats the outer pixels

[Moritz Barsnick]

On Tue, Jun 09, 2015 at 00:10:36 +0200, Jesper Taxbøl wrote:
> Is there a way to specify a more generic format inside the filter chain,
> and only apply h264 in the end?

Yes, with the format filter.

With this filter and yuv420p input, my ffmpeg fails:
  "[0:v:0]crop=1440:1:0:720,scale=1440:1440[OUT]"
With this filter and yuv420p input, it "works":
  "[0:v:0]format=yuv444p,crop=1440:1:0:720,scale=1440:1440[OUT]"

As you're going to be doing overlays, you may have to be careful about
implicit conversions. libavfilter tries to match the supported and
preferred color spaces at the joining points of the filters, and
inserts "format" filters where necessary.

Moritz