how to discover ffenc_mpeg4's _real_ supported input format

[Farkas Levente]

hi,
if i run gst-inspect ffenc_mpeg4 show:
  SINK template: 'sink'
    Availability: Always
    Capabilities:
      video/x-raw-rgb
      video/x-raw-yuv
      video/x-raw-gray
but it's not too usable eg:
gst-launch videotestsrc ! "video/x-raw-yuv,format=(fourcc)UYVY" !
ffenc_mpeg4 ! fakesink
couldn't link, even though it's raw-yuv. of course format=(fourcc)I420
or an ffmpegcolorspace can solve the problem. but my real question in
this case:

how can i discover in advance which input formats really supported by an
element?

eg. ffenc_mpeg4. i'd like to save the cpu usage of ffmpegcolorspace
conversion which can be very high in case of a high fps large video stream.
but currently i don't see any way to discover ALL supported input video
format for ffenc_mpeg4.

thanks in advance.
regards.

ps. of course my real problem is more complex but it's the cause of the
problem.


-- 
  Levente                               "Si vis pacem para bellum!"