[M4IF Technotes] Visual Object Sequence Start Code

[emre.aksu nokia.com]

Hello Nitin, all,
> "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 believe this is true when you have "Combined Configuration / Elementary Stream", e.g. , when you are streaming. Another section which is above this paragraph is called for "Seperate Configuration / Elementary Stream" , where it states:
"When coded visual objects are carried within a Systems bitstream defined by ISO/IEC 14496-1:1999, configuration information and elementary stream data are always carried separately.  "
So, now I realized that I have to re-phrase my question, especially making the following distinction to resolve the misunderstanding:
Assuming that the bitstream is stored in a container file (e.g. a 3GP file or an MP4 file), where the configuration information is seperated from the elementary stream, and present in the VisualSampleEntry box, is it allowed to have the configuration information in the video track data, and possibly starting with a VOS_Start_Code without a VOS_end_code?
> 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 ??

I believe the answer to "when" is very much an implementattional issue, how you'd like to cope with channel errors or loss of data in this case. 
Best Regards,
Emre
> -----Original Message-----
> From: ext Nitin Gupta--DSP, Noida [mailto:gnitin   noida.hcltech.com]
> Sent: 10. September 2002 11:47
> To: technotes   lists.m4if.org
> Subject: RE: [M4IF Technotes] Visual Object Sequence Start Code
> 
> 
> 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
> > 
> > 
> _______________________________________________
> 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
>