[Ffmpeg-devel] Applying vhooks to only some output streams

Michael Niedermayer michaelni
Wed Jan 31 22:35:28 CET 2007


On Wed, Jan 31, 2007 at 01:58:34PM +0000, James Le Cuirot wrote:
> Hi guys. I am using ffmpeg to encode two videos at once. I'm also using
> the watermark vhook. Ideally I'd like to only apply the watermark to
> just one of the videos but as far as I can tell, this isn't possible at
> the moment. I could just encode the videos separately but time is
> crucial and this actually operates behind the scenes of a web front
> end, which makes it a little flakey. The less times I have to run
> ffmpeg, the better!
> I had a quick look at the source to see whether it was feasible. I
> thought that maybe it would work if a copy of each frame were made
> before applying the hooks. Which frame then gets sent to the output
> each stream would depend on the position of the vhook argument.
> ffmpeg -i foo.avi bar1.avi bar2.avi -vhook "blah.so" bar3.avi bar4.avi
> So in the above example, the hook would only be applied to bar3.avi and
> bar4.avi. For multiple vhooks, I guess you could restrict it to applying
> either all or none of them, otherwise it would get too messy. So would
> this work or am I being naive here?

i think you should look at the video filter discussions as
hacks on top of vhook are not going to be accepted, the correct solution
is a better filter layer which supports arbitrary filter graphs with
multiple outputs and inputs


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Republics decline into democracies and democracies degenerate into
despotisms. -- Aristotle
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