[x264-devel] Re: Slices in x264

[mahesh k]

I am new to this group and I need to know how half pixel interpolarion is
done at the boundaries.....Can any one plz help me regarding this.....


Thanks & regards,
Mahesh


On 1/17/07, Guillaume Poirier <gpoirier at mplayerhq.hu> wrote:
>
> Hi Måns,
>
> Måns Rullgård wrote:
> > Guillaume Poirier <gpoirier at mplayerhq.hu> writes:
> >
> >
> >>Hi,
> >>
> >>List, Peter wrote:
> >>
> >>>Hello everyone,
> >>>
> >>>
> >>>
> >>>I am new to this group although experienced with H.264. I tried to use
> >>>the x264 encoder to prepare sequences for an error-resilience test.
> >>>
> >>>I was very surprised, when I discovered, that x264 CAN NOT produce
> >>>slices! Slices are the basic tool to cope with packet-losses over
> >>>IP-based networks (without retransmission), and in fact can make a huge
> >>>difference for subjective quality, in particular at high loss-rates.
> >>
> >>Very basic indeed. _I_ think it's better to add more advanced parity
> >>(which allow the errors to be recovered) infos somewhere in the
> >>transport layer stream than using slices.
> >
> >
> > Using error correcting coding at the transmission layer substantially
> > increases the bitrate.  With slices a transmission error will ruin the
> > rest of the slice, while other slices still decode properly.
> > Sometimes a little damage here and there is acceptable if it means you
> > can keep the bitrate down.  Besides, you don't always have control
> > over the transmission encoding.
> >
> > Put another way, slices limit the scope of the damage caused by
> > whatever transmission errors make it through your error correction
> > layers.
> >
> > Anyone who has watched digital TV should appreciate the usefulness of
> > slices.
>
> Mmmm. I guess I did not understand what "error concealment" meant. My
> dictionary translates it to "dissimulation des erreurs" which more or
> less translates back in English as "error hiding", which by my book
> means that if an error occurs, it doesn't show, up to a certain amount
> of errors you can't recover.
>
> As far as I understand, slices don't allow that, that's why I thought
> that better error correction blocks was the solution.
>
> But now that I understand what "error concealment" means, and I see
> that slices seem like the right tool for that job.
>
> Sorry for the trouble. I'm learning smth new every day :-)
>
>
> >>>Did I miss something here, or is it true that x264 can only produce 1
> >>>slice per frame???
> >>
> >>It used until r609 to but it was replaced by a much better and faster
> >>multi-threaded encoding mode.
> >
> >
> > Multithreaded encoding and slices are really distinct features.
> > Slices may be desired, as the OP says, with or without multithreading.
>
> Loren, Out of curiosity, did you remove sliced encoding support
> because it was too deeply "interleaved" with multi-threaded support,
> so your new multi-threaded encoding mode had to make sliced encoding
> go away? Or are there other reasons?
>
> Guillaume
>
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