[x264-devel] Re: Slices in x264

[Ryan Dalzell]

On Tuesday 16 January 2007 22:57, Jeff Clagg wrote:
> I don't have much to add beyond that Mans is right.
>
> From the most optimistic reckoning, using FEC at the transport stream
> layer adds 8.5% overhead to EVERY PID IN THE STREAM; compare that to
> using a few slices per frame, thus adding maybe 2% overhead in the
> video stream only - which may be enough to add a satisfactory amount of
> error resilience.

This is true, but the extra error resilience is only satisfactory because in 
digital TV streams there is an I picture every half a second which will fix 
up any accumulating errors. And I'd be certain that this regular I picture 
adds a lot more than 8.5% to the video bitrate. In other applications it 
would be cheaper and more effective to add FEC to the stream.

However, the original questioner was working in a packet based environment 
and slices are useful there so that one lost packet does not mean one lost 
picture. But error *concealment* would still need to be performed very soon 
after despite this extra error *resilience*.

Cheers,
-Ryan

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