[x264-devel] Regarding disabling 4x4 in JM code

[mahesh k]

Dear peter,
I am talking about decoder only. I will explain u my problem more clearly.

Right now our decoder works properly with our encoder. Now we need to make
this decoder standardised in the sense that it should accept any other
bitstream(for example i want to decode JM encoders output with my decoder).

After reading the syntax elements as per baseline standard I need to check
whether this is implemented or not in my decoder and return the error still
needs to be implemented. the intent was that the code shouldnot crash in
such situations instead return proper error code.

I went through the section that u told me. But my doubts were,
i dont understand what 0_0_0 signify in name of MB type. Also in table
7.13mb_types for P slices, what do we mean by inferred type.

Also tell me can we idetify the prediction mode from mb_type itself?

thanks in advance,
mahesh.

On 8/7/07, List, Peter <Peter.List at t-systems.com> wrote:
>
>  Dear Mahesh,
>
> if you are talking about a DECODER intra 4x4 is a must, if you want to be
> standard conform in all cases (for any profile).
>
> If you are talking about  ENCODERS you don't need to implement intra-4x4
> but only use intra-16x16 (resulting in very poor intra performance).
>
>
>
> I don't understand what you mean with:
>
> But we want to decode any standard bitstream that is as per standard but
> return the error code accordingly .
>
>  About mb_type read in  "Recommendation H.264" (ISO/IEC 14496-10)
> paragraph 7.4.5
>
>
>
> Peter
>
>
>   ------------------------------
>
> *Von:* mahesh k [mailto:maheswarreddy.k at gmail.com]
> *Gesendet:* Dienstag, 7. August 2007 11:22
> *An:* Mailing list for x264 developers
> *Betreff:* Re: [x264-devel] Regarding disabling 4x4 in JM code
>
>
>
> thanks for ur reply. Plz tell me whether intra 4x4 is must in base line
> profile or it is an optional.
>  Can't we run the baseline profile decoder without 4x4 as per standard?
> I need this because at present we have not implemented this 4x4 mode But
> we want to decode any standard bitstream that is as per standard but return
> the error code accordingly .
> Also I am confused with the syntax element mb_type.
> What values does mb_type should have if i need to check whether this is an
> 4x4 or 16x16.
> Also plz tell me in clear about this mb_type and ma_mde.
> If possible refer some good document on this.
>
> Thanks in advance.
>
> On 8/7/07, *List, Peter* <Peter.List at t-systems.com> wrote:
>
>
> > mahesh k wrote:
> > > I want a baseline ecoded bit stream in which intra4x4 predition mode
> > > should not be present.
> >
> > Note (but you probably already know it): of course intra4x4 is part of
> > baseline.
>
> Also note that intra4x4 is NOT some fancy add on for intra-coding like
> some people think 4x4 motion estimation is.
> Intra4x4 is the basic intra coding mode! It is usually used for the
> majority of intra-macroblocks. Intra-16x16 is only used for very uniform
> macroblocks like blocks from a blue sky or something like that.
> Regards, Peter
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