[M4IF Technotes] hi

[Gary Sullivan]

Reply interspersed:
+> -----Original Message-----
+> From: G Chandra Sekhar Reddy [mailto:gchandra   tataelxsi.co.in] 
+> Sent: Thursday, September 13, 2023 11:30 PM
+> To: Jani Huoponen; Sudhakar Rao Kimidi; technotes   lists.m4if.org
+> Subject: Re: [M4IF Technotes] hi
+> 
+> 
[snip]
+> The Levels restrict maximum number of bits per VideoPacket, 
+> making these
+> synchronization points appear within some fixed interval 
+> (interval in bits,
+> in bitstream).
Are you sure about that statement?  I don't think it's true.
Can you point to where such a restriction can be found?
+> This is only restriction on the maximum size. The actual 
+> sizes (thereby
+> synchronization intervals) can be less than this maximum size.
+> If you want fixed size (thereby fixed synchronization 
+> intervals), you can
+> use stuffing.
I think you're right.  I guess some combination of MCBPC stuffing and
bit stuffing can enable the encoder to hit any desired
reasonably-large packet size.
+> About the legal interval you are taking about, I think only 
+> restriction is
+> that they shall be at BYTE-Boundaries.
They also must start at macroblock boundaries.  Each packet must
contain the bits to represent an integer number of macroblocks.
+> 
+> Does the standard restrict VOP size in bits to some maximum 
+> value in any
+> Profile / Level?
Not that I'm aware of.
+> 
+> Chandra
+> *************************************************************
+> *********
+> Chandra Sekhar Reddy G.,
+> TATA ELXSI Ltd.,
+> WhiteField Road, Hoody,
+> BANGALORE, INDIA - 560048.
+> TEL: +91-80-8410148, 8411811, 8411812 (Ext:254),
+> FAX: +91-80-8410152, 8411813.
+> EMAIL: gchandra   tataelxsi.co.in
+> WEB: www.tataelxsi.com
+> *************************************************************
+> *********
+> 
+> ----- Original Message -----
+> From: Jani Huoponen <Jani.Huoponen   hantro.com>
+> To: Sudhakar Rao Kimidi <sudhakar   cradle.com>; 
+> <technotes   lists.m4if.org>
+> Sent: Thursday, September 13, 2023 9:25 PM
+> Subject: RE: [M4IF Technotes] hi
+> 
+> 
+> > Dear Sudhakar,
+> >
+> > > Dear all,
+> > >
+> > > Can somebody help me with the answers for the following.
+> > >
+> > > 1. Which method of Quantization is used in MPEG-4 video
+> > > simple profile?
+> >
+> > Type 2.
+> >
+> > > Are both methods of Quantizations used in MPEG-4 Video 
+> simple profile?
+> >
+> > No. Type 1 (quantization matrices) is not used in Simple profile.
+> >
+> > > 2. Is fixed interval synchronization supported in simple
+> > > profile? Is it
+> > > compulsory to use the method? Is there any mentioning about it in
+> > > syntax?(This method requires that VOP start codes and
+> > > resynchronization
+> > > markers appear only at legal fixed interval locations in the
+> > > bitstream)
+> >
+> > If you mean that should encoded VOPs have a fixed time 
+> interval between
+> them
+> > then the answer is yes. Simple profile supports this. See 
+> section 6.3.3.
+> in
+> > the 14496-2 standard, the field called "fixed_vop_rate" 
+> explains how this
+> > works. It is not a compulsory method, i.e., VOPs can have 
+> variable time
+> > intervals between them.
+> >
+> > BR, Jani
+> >
+> > ------------------------------------------------------------
+> > Jani Huoponen
+> > Engineering Manager, System Design
+> > Hantro Products Oy
+> > Nahkatehtaankatu 2, 90100 Oulu, Finland
+> > +358-40-5272676
+> > ------------------------------------------------------------
+> >
+> > _______________________________________________
+> > Technotes mailing list
+> > Technotes   lists.m4if.org
+> > http://lists.m4if.org/mailman/listinfo/technotes
+> 
+> _______________________________________________
+> Technotes mailing list
+> Technotes   lists.m4if.org
+> http://lists.m4if.org/mailman/listinfo/technotes
+>