[M4IF Technotes] Visual Object Sequence Start Code

[Nitin Gupta--DSP, Noida]

Hi all,
	I have a querry regarding the visual object sequence header. The
standard mentions 
"The Visual Object Sequence Header, the Visual Object Header and the Video
Object Layer Header may be repeated in a single visual bitstream. Repeating
these headers enables random access into the visual bitstream and recovery
of these headers when the original headers are corrupted by errors."
in section 6.2.1 of the video standard on page no 33.
I want to know that when Visual Object Sequence Header, the Visual Object
Header and the Video Object Layer Header are repeated, do they have to be
present in the same order again or is it possible to just get a VOL header
alone ??
Thanx & Regards,
Nitin.
-----Original Message-----
From: emre.aksu   nokia.com [mailto:emre.aksu   nokia.com]
Sent: Tuesday, September 03, 2023 7:16 PM
To: chris   avipix.com
Cc: technotes   lists.m4if.org
Subject: RE: [M4IF Technotes] Visual Object Sequence Start Code
Hi Christopher,
> Having multiple visual_object_sequence_start_code's without question 
> should be supported by all decoders.  There are many 
> applications that 
> need to support this including live broadcasting and other 
> applications 
> involving potential channel errors.

For sure, I have no problems with that. I think you can put in as many
visual_object_sequence_start_codes as you like, as long as you have a
visual_object_sequence_end_code finalizing a previous strat code, I think.
Otherwise, how can we identify a serialized structure of visual object
sequences?
Once again, a reference from 14996-2:2001:
Section 6.1.1:
" Visual object sequence is the highest syntactic structure of the coded
visual bitstream.
A visual object sequence commences with a visual_object_sequence_start_code
which is followed by one or more visual objects coded concurrently. The
visual object sequence is terminated by a visual_object_sequence_end_code."
How should we interpret the first and last sentences together, if we allow
randomly inserted visual_object_sequence_start_codes ending a previous
visual object sequence? The very same structure (
visual_object_sequence_start_code followed by another
visual_object_sequence_start_code) can be interpreted as a frame loss by the
decoder, which was expecting a visual_object_sequence_end_code before a
start code as stated in section 6.1.1.
Best Regards,
Emre
Emre Baris Aksu
Nokia Corp.
> -----Original Message-----
> From: ext Christopher Wendt [mailto:chris   avipix.com]
> Sent: 03. September 2002 16:03
> To: Aksu Emre (NMP/Tampere)
> Cc: technotes   lists.m4if.org
> Subject: Re: [M4IF Technotes] Visual Object Sequence Start Code
> 
> 
> Hi Emre,
> 
> Having multiple visual_object_sequence_start_code's without question 
> should be supported by all decoders.  There are many 
> applications that 
> need to support this including live broadcasting and other 
> applications 
> involving potential channel errors.
> 
> -Chris
> 
> _____________________________________
> Christopher Wendt, Avipix Technology Corp
> chris   avipix.com
> 484.951.4932
> http://www.avipix.com
> 
> 
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