[M4IF Technotes] GMC

[Yoshinori Suzuki]

Dear Rob,
Thank you for the correction.
I fully agree to your suggestion.
All the decoders should support all functions in standard.
And I hope that the all tools in adavanced simple are implemented in 
an encoder for taking advantage of the feature of Advanced Simple 
on the visual quality.
Best regards,
Yoshinori Suzuki
Hitachi, Ltd.
Rob Koenen wrote:
> 
> Suzuki-san,
> 
> > ISMA is just example, not generic.
> > My suggestion is not to add its own levels, that is to define
> > the limitation for the current levels.
> 
> A limitation on the current Level definitions is axactly the same
> as defining new Levels ...
> 
> > I think that
> > 1. the limitation on encoding defined by an assosiation does not
> >    cause the prombles for existing products, and
> 
> I agree in principle.
> However, the limitation will then also be exploited in the decoder,
> which then does go on to cause problems, because, as you rightly say below,
> such a decoder will then not be able to decode all permitted bitstreams
> anymore ...
> 
> If it is just a limitation on the encoder without consequences for the
> decoder then there is no problem at all. There are people today that
> claim they support Advanced Simple Profile, while they do not implement
> e.g. B frames or 1/4 pel motion compensation. As long as this is only
> the encoder, there is no problem with interoperability. The only problem
> is with the quality of the encoded video, which is not nearly as good
> as it could have been. If these tools, however, are not implemented in
> the DEcoder, then a claim to support Advanced Simple is simply a false
> statement (also called "lie").
> 
> > 2. the limitation on decoder in the specific association does not
> >    cause the prombles, though such decoder could not decode all
> >    standard bitstreams.
> 
> Best,
> Rob
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