Re[2]: [XviD-devel] scene change detecting in Bframes mode

[Michael Niedermayer]

Hi

On Tuesday 20 August 2002 15:33, Christoph Lampert wrote:
> On Tue, 20 Aug 2002, peter ross wrote:
> > >I frames are smaller because they use predictions of DCT coefficients
> > >between macroblocks, while in P frame all blocks are independant. (OK
> > >I might be wrong here, please correct me).
> >
> > syskin, i think you've got I-frames and P-frames mixed up.
>
> No, he didn't. He just talks about INTRA blocks. A P-frames full of
> INTRA-blocks is larger than a I-frame full of the same INTRA-blocks,
> because in I-frames there's AC/DC prediciton between blocks and for
> P-frames, there is not.
ehh, there is no ac/dc prediction from inter -> intra blocks, but there is 
ac/dc prediction between intra blocks even in p frames, the difference 
between I and P is IIRC 1 mb skip bit & the mb-type is larger as it must be 
able to encode inter & inter4V blocks too

[...]

Michael