[M4IF Technotes] CBPC and CBPY

[Herbert Thoma]

Bart Lehane schrieb:
> 
> Hello,
> 
> In a rectangular I frame, is it possible to have values of cbpy (coded
> block pattern for luminance) that do not equal '1111', or values of cbpc
> (cbp for chrominance) that do not equal '11'??
> 
> If true, would this give a pattern code not equal to '111111' which
> would mean that there would be no DCT coefficients for a particular
> block?? (i.e if pattern_code[5] = 0, then the second chrominance block
> would have no dct coefficients)
> 
> First of all is this scenario possible, where an intra macroblock
> contains a block with no (AC) DCT coefficients? If it is possible, what
> values would go into that block?

In an I frame the DC coefficient is not regarded when computing cbp.
The DC coefficient is allways present and transmitted. If the pattern
code for a particular block is 0 then only the DC coefficient is present
and all pixels of that block get the same value according to the
DC coefficient.
Regards,
 Herbert.
> Thanks in advance,
> 
> Bart
> 
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-- 
Herbert Thoma
FhG-IIS A, Studio Department
Am Wolfsmantel 33, 91058 Erlangen, Germany
Phone: +49-9131-776-323
Fax:   +49-9131-776-399
email: tma   iis.fhg.de
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