[Mp4-tech] [Video] intraPrediction H.264

[Gary Sullivan]

Regarding question 1: There are actually two things that the decoder
must predict in the Intra prediction design.  First, the decoder
predicts what the spatial prediction mode will be.  Then, based on that
prediction and some syntax, the decoder figures out what the actual
spatial prediction mode will be and performs the second prediction --
which is the prediction of the sample values themselves.  The
dcOnlyPredictionFlag is used for determining what the prediction of the
spatial prediction mode wll be, not for determining which modes are
allowed for the actual spatial prediction mode.  You seem to be mixing
it up with the spatial prediction mode itself, which is understandable.
Regarding question 2: The basic idea is to find a simple parameterized
curve fit that produces an equation of the form shown in equation 8-76.
The variables H and V capture the overall horizontal and vertical slope
behavior in a single variable each.  I believe the original proposal for
this was from Gisle Bjontegaard (although I am not sure).  A little
digging in old document archives could lead you to the proposal document
that described it.
Padua affords this kindness, son Petruchio.
Gary Sullivan
________________________________
	From: mp4-tech-bounces lists.mpegif.org
[mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Bule
	Sent: Monday, August 30, 2023 1:06 AM
	To: mp4-tech lists.mpegif.org
	Subject: [Mp4-tech] [Video] intraPrediction H.264
	Hi 
	i'm student of University of Padua and I'm writing a thesis on
the H.264 standard with great interest on intraprediction process but
there are some question I'm not able to answer..i hope you can help me.
	1-if dcOnlyPrediction flag i set to 1 I think it's meaning that
it is avaible only the DC prediction but in chapter 8.3.1.1 Derivation
process for the Intra4x4PredMode i read that the value of this variable
is set to one if one the two macroblocks A or B are not avaible but this
is no clear. For istance if i can refer only to macroblock A ,the one on
the left of the current MB ,i can use the 4x4Horizontal and
4x4Horizontal_Up prediction and not only the DC mode. Perhaps i have not
understand the meaning of dcOnlyPrediction flag.
	2-  In Chapter 8.3.2.4 specification of Intra16x16_Plane
prediction mode I find the function which define the value of the
prediction using H and V...why this two parameters ( H and V ) are so
defined ? and it's possible to explain why the prediction function is so
defined ? 
	Thanks
	Luca Bulegato
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