[Mp4-tech] [H.264] about causal contraint of HRD

[Gary Sullivan]

Changhsu,
The idea is that an encoder should generate a bitstream that can be
decoded properly without problems caused by:
1) A need to buffer up too much data in the decoder before the decoder
can start decoding and displaying the video; or
2) A lack of awareness of how long the decoder must wait to begin
playing the video before being assured that when the time arrives to
display future pictures, those pictures will have arrived at the decoder
in time to decode them and display them (avoiding "glitches" during
decoding); or
3) A need for the decoder to operate too quickly.
So the HRD specifies constraints on the bitstream that are sufficient to
make it possible to avoid those problems.  These constraints govern
relationships between decoding times, output times, and the amount of
data necessary for buffering.
Best Regards,
Gary Sullivan
+> -----Original Message-----
+> From: mp4-tech-bounces lists.mpegif.org 
+> [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of 
+> changhsu yahoo.com
+> Sent: Friday, February 04, 2024 3:27 PM
+> To: mp4-tech lists.mpegif.org
+> Subject: [Mp4-tech] [H.264] about causal contraint of HDR
+> 
+> I had a few questions about HDR after studying a few
+> papers. Hope someone will help me out.
+> My understanding is that causal constraint is used by
+> the encoder to mimic(trace) buffer arrival timing of
+> the decoder. (via pre_dec_removal_delay)
+> Is this atatement correct?
+> 
+> Why do we need it in h264? What good it can do for us?
+> 
+> What is the  drawback of a non-causal HDR? larger
+> delay, larger buffer or anything else?
+>  
+> 
+> 
+> 		
+> __________________________________ 
+> Do you Yahoo!? 
+> Yahoo! Mail - Find what you need with new enhanced search.
+> http://info.mail.yahoo.com/mail_250
+> _______________________________________________
+> NOTE: Please use clear subject lines for your posts. Include 
+> [audio, [video], [systems], [general] or another 
+> apppropriate identifier to indicate the type of question you have.
+> 
+> Note: Conduct on the mailing list is subject to the 
+> Antitrust guidelines found at 
+> http://www.mpegif.org/public/documents/vault/mp-out-30042-Ant
+> itrust.php
+>