[Ffmpeg-devel] v4l2 arbitrary field order support

Richard Khoury richiek
Wed May 31 02:31:50 CEST 2006

> I am all for this change; I just need to test it on some other
> distribution and then I'll commit it (it seems that every linux
> distribution likes to break v4l2 compilation in new ways :).
> I tried to answer your first mail about this subject, but my mail
> bounced; sorry for the delayed answer
Awesome, thanks Luca.

> Yes, I did that because I expect PAL or NTSC video to be always
> interlaced.
> Of course the situation can be improved and if there is some way to make
> this flag configurable, I'll be happy to commit the necessary changes.
> > I can't quite see a nice way to add arbitrary
> > field order support without adding an extra field to the
> > AVFormatParamaters structure. Is there another way I can be doing
> > this?
> Well, adding an extra field to AVFormatParamaters is the only way I can
> see... Maybe someone who knows the libavformat API better than me can
> suggest another way?
AVFormatParameters looks like the only interface we can use, so the
question is what is the best way to do it. I'm trying to think of a
generic way that could be beneficial to other format users and the
only thing I can think of is using a bunch of "user" void pointers at
the end of the AVFormatParameters structure that each individual
format can interpret in their own way. A new configuration structure
could be defined within v4l2.c that we can populate and assign to the
void pointer and that the device_init() function can accept as an
 ... it's that or we add one varaible specific for v4l2 grabbing to
the AVFormatParameters structure (not generic or extensible).

What do you think?


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