[Libav-user] help with raw fifo as movie src & overlay

[gstream at ccc2.com]

> 2012/2/15  <gstream at ccc2.com>:
>
>> assume its because of the RTSP codec and timestamps not being the most
>> accurate.
>> I am keen for advice on constructing the filter you mentioned, are there
>> any tutorials?
>
> I think more probably timestamps are ok, but inter-frame interval
> (FPS) may be not very accurate. And maybe overlay filter just gets one
> frame from one source, and one from another, and puts together, thus
> if one camera may "forget" to send particular frame sometimes, the
> second source will "be late" on visualization. If we had a filter that
> forces constant frame rate, this could be solved. (Just speculations
> again)
>
>> Also a bit of a NooB Q. but is there a way to update/change parameters
>> once the cmd has been started? In particular if we can get this delay
>> fixed, I am assuming some form of drift over a 60+ period and we would
>> need to dynamically adjust this over time.
>
> For cmdline util, it's impossible. For API that's re-initializing all
> filtering stuff. You can do it, but it's a lot of code. You must read
> your streams and push to filters manually, not by 'movie' filter.
>
> --
> Andrey Utkin
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>
Your a good man for helping this far Andrey. One last Q for this. I am
trying to understand the mapping between the pix_fmt and fourcc. ie if I
want to output rawvideo for fourcc AYUV how do I work out what the pix_fmt
version is?

Thx again
Art