WMV9 Specification will identical with VC_1 ?

[tonytang]

I notice reserved some syntax bits(set zeros)in vc_1 specification while the bits have real semantics in wmv9 specification old version ,it seems vc_1 only subset of wmv9. And wmv9 decoder can decode vc_1 stream ,the vice is not true. And wmv9 specification modified continually,Does it will fully identical with vc_1?

[Episode]

Actually, VC-1 is not a subset of WMV9. WMV9 itself is an implementation of VC-1 (much like x264 is implementation of mpeg4 avc and xvid of mpeg4 asp). Iirc only profile that is not supported in VC-1 is complex profile which is highly uncommon. Other than that, VC-1 will decode all other WMV9 files without any problems because it's the same thing. I don't quite follow what you meant by that "wmv9 specification modified continually" thing, but I'm sure that wmv9 specification hasn't been changed at all since it was released.

[bond]

there are incompatibility issues of wmv9 with vc-1, as i described here (http://forum.doom9.org/showthread.php?t=113968)

among the issues are the reserved bits as you mentioned

it also has to be mentioned that m$ currently has the interest to be compliant with vc-1 (imho not obvious as m$ generally tries to _not_ be compliant with public standards), so there shouldnt be many problems with non-vc-1 compliant wmv9 streams

[tonytang]

But design media player ,it's should cover all ,and there exist many tools can encode wmv9 streams.It's troublesome thing.

[bond]

But design media player ,it's should cover all ,and there exist many tools can encode wmv9 streams.It's troublesome thing.which tools support wmv9 encoding that dont use m$' codec or a strictly compliant vc-1 codec? i dont know any...

what is "design media players"?