[x264-devel] Regarding Intra macroblock in P Slice

[Sergey A. Sablin]

In I-slices only Intra modes are allowed.
constrained_intra_pred_flag indicates whether pixels from Inter-coded
macroblock in non-Intra slices will be used for intra prediction or not.
constrained_intra_pred_flag = 0 indicates that there is no any
restrictions, while constrained_intra_pred_flag = 1 indicates that for
intra prediction process in non-Intra slices pixels from inter-coded
macroblock shall be inferred as 2^(bit_depth-1), ie 128 for 8-bit case.

Sergey.

mahesh k wrote:
> Does this mean that if the flag is set then we should not have a Inter 
> predicted macroblock in a I slice. This is my poor understanding from 
> the standard. Am i correct?
> 
> On 11/5/07, *Eric Viscito* <eric at ev-consulting.com 
> <mailto:eric at ev-consulting.com>> wrote:
> 
> 
>     Cut and paste from the specification:
> 
>     "constrained_intra_pred_flag equal to 0 specifies that intra prediction
>     allows usage of residual data and decoded samples of neighbouring
>     macroblocks coded using Inter macroblock prediction modes for the
>     prediction of macroblocks coded using Intra macroblock prediction modes.
>     constrained_intra_pred_flag equal to 1 specifies constrained intra
>     prediction, in which case prediction of macroblocks coded using Intra
>     macroblock prediction modes only uses residual data and decoded samples
>     from I or SI macroblock types."
> 
> 
>     On Mon, November 5, 2007 7:55 am, mahesh k wrote:
>      > Thanks for your reply,
>      >
>      > Can you please tell me what for constrained intra prediction flag
>     is used.
>      >
>      > with best regards,
>      > Mahesh.
>      >
>      >
>      > On 11/5/07, Yongmin Tan < angelwings at sjtu.edu.cn
>     <mailto:angelwings at sjtu.edu.cn>> wrote:
>      >>
>      >>  I think there is no such syntax element . You can just neglect the
>      >> intra
>      >> analysis part in the mode decision for P slice.
>      >>
>      >>
>      >>
>      >> *发件人:* x264-devel-bounces at videolan.org
>     <mailto:x264-devel-bounces at videolan.org> [mailto:
>      >> x264-devel-bounces at videolan.org
>     <mailto:x264-devel-bounces at videolan.org>] *代表 *mahesh k
>      >> *发送时间:* 2007年11月5日 15:34
>      >> *收件人:* Mailing list for x264 developers
>      >> *主题:* [x264-devel] Regarding Intra macroblock in P Slice
>      >>
>      >>
>      >>
>      >> Hi all,
>      >>
>      >>
>      >>
>      >> Is there any syntax element(flag) which indicates the absence of I
>      >> macroblocks in P slice in any case. My purpose is not to have any
>      >> Intramacroblock in P slice. Please help me.
>      >>
>      >>
>      >>
>      >> Regards,
>      >>
>      >> Mahesh.
>      >>
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>      >>
>      >>
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> 
> 
> 
> 
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