[Libav-user] Security Camera App - multiplexing and visual timestamps

Carl Eugen Hoyos cehoyos at ag.or.at
Thu Nov 24 11:11:21 CET 2011

Camera Man <i.like.privacy.too at ...> writes:

>     e.g., for (2) there might be a way to multiplex macroblocks from
>       different pictures, without actually decoding them to image and
>       re-encoding (thus avoiding the motion compensation estimation,
>       which is super expensive, and the effects of requantization)
>     for (1), there might be a way to increase the picture size to e.g
>       1280x1000, and somehow encode the timestamp into the new 40 pixels
>       (again, without decoding and re-encoding everything?)

While both may be possible in theory (I don't know) it would certainly require
some effort to program this. (It is not supported by current FFmpeg.)

>     And assuming that I have to re-encode, is there a some
>       hw-assisted encoder supported by ffmpeg that would be able to do
>       this encoding in real time and without eating too many watts?

I thought for any given hardware encoder, there is a software encoder that is
both faster (fps) and produces better quality (but I did not test myself) ;-)

But seriously:
What encoder are you using with what options? I would be surprised if that
couldn't be accelerated.
And no, FFmpeg does not support hardware encoders. Apart from "patch welcome", I
assumed above is the reason nobody sent one.

Carl Eugen

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