List Info

Thread: back_ptr description unclear
back_ptr description unclear
user name
 2007-01-23 02:10:43 

  


  

    nut.txt says:
| back_ptr_div16 (v)
|     back_ptr = back_ptr_div16 * 16 + 15
|     back_ptr must point to a position within 16 bytes of a syncpoint

|     startcode. [...]

Does "within 16 bytes" mean before or after the syncpoint startcode?
This description also doesn't mention that this value is relative.


I think the semantics were intended to be similar to syncpoint_pos_div16
in the index, so probably that description can be copied and adapted:

| syncpoint_pos_div16 (v)
|     offset from beginning of file to up to 15 bytes before the syncpoint

|     referred to in this index entry. Relative to position of last
|     syncpoint.


Regards,
Clemens
_______________________________________________
NUT-devel mailing list
NUT-develmplayerhq.hu
http://lists.mplayerhq.hu/mailman/listinfo/nut-devel


  

  
  
   
     
    

  

    Re:  back_ptr description unclear
  


  

     user name

     2007-01-23 15:39:32
  


  

    

  


  

    On Tue, Jan 23, 2007 at 09:10:43AM +0100, Clemens Ladisch wrote:
> nut.txt says:
> | back_ptr_div16 (v)
> |     back_ptr = back_ptr_div16 * 16 + 15
> |     back_ptr must point to a position within 16 bytes of a syncpoint

> |     startcode. [...]
> 
> Does "within 16 bytes" mean before or after the syncpoint startcode?
> This description also doesn't mention that this value is relative.

> 
> I think the semantics were intended to be similar to syncpoint_pos_div16
> in the index, so probably that description can be copied and adapted:
> 
> | syncpoint_pos_div16 (v)
> |     offset from beginning of file to up to 15 bytes before the syncpoint

> |     referred to in this index entry. Relative to position of last
> |     syncpoint.

except back_ptr is relative to the current position, not absolute/from
beginning of file. and within 16 bytes is supposed to mean that the
startcode begins on the pointed-to byte or one of the 15 following

bytes. i suppose this could use some clarification in the spec. 

rich
_______________________________________________
NUT-devel mailing list
NUT-develmplayerhq.hu
http://lists.mplayerhq.hu/mailman/listinfo/nut-devel


  

  
  
   
     
    

  

     back_ptr description in nut.txt
  


  

     user name

     2007-01-26 03:25:59
  


  

    
Rich Felker wrote:
> On Tue, Jan 23, 2007 at 09:10:43AM +0100, Clemens
Ladisch wrote:
> > nut.txt says:
> > | back_ptr_div16 (v)
> > |     back_ptr = back_ptr_div16 * 16 + 15
> > |     back_ptr must point to a position within 16
bytes of a syncpoint
> > |     startcode. [...]
> > 
> > Does "within 16 bytes" mean before or
after the syncpoint startcode?
> > This description also doesn't mention that this
value is relative.
> 
> [...] and within 16 bytes is supposed to mean that the
> startcode begins on the pointed-to byte or one of the
15 following
> bytes. i suppose this could use some clarification in
the spec. 

Okay.  Changes made:
- replaced "within 16 bytes of" with "up to
15 bytes before"
- mentioned that it's relative
- replaced "original syncpoint" with "current
syncpoint" (both terms were
  used for the same syncpoint)

_______________________________________________
NUT-devel mailing list
NUT-develmplayerhq.hu

http://lists.mplayerhq.hu/mailman/listinfo/nut-devel


  


  

    
  

  
  
   
     
    
 
        
    

    
    

  

    Re:  back_ptr description in nut.txt
  


  

     user name

     2007-01-29 18:44:25
  


  

    
Hi

On Fri, Jan 26, 2007 at 10:25:59AM +0100, Clemens Ladisch
wrote:
> Rich Felker wrote:
> > On Tue, Jan 23, 2007 at 09:10:43AM +0100, Clemens
Ladisch wrote:
> > > nut.txt says:
> > > | back_ptr_div16 (v)
> > > |     back_ptr = back_ptr_div16 * 16 + 15
> > > |     back_ptr must point to a position
within 16 bytes of a syncpoint
> > > |     startcode. [...]
> > > 
> > > Does "within 16 bytes" mean before
or after the syncpoint startcode?
> > > This description also doesn't mention that
this value is relative.
> > 
> > [...] and within 16 bytes is supposed to mean that
the
> > startcode begins on the pointed-to byte or one of
the 15 following
> > bytes. i suppose this could use some clarification
in the spec. 
> 
> Okay.  Changes made:
> - replaced "within 16 bytes of" with "up
to 15 bytes before"
> - mentioned that it's relative
> - replaced "original syncpoint" with
"current syncpoint" (both terms were
>   used for the same syncpoint)

patch applied

[...]
-- 
Michael     GnuPG fingerprint:
9FF2128B147EF6730BADF133611EC787040B0FAB

Republics decline into democracies and democracies
degenerate into
despotisms. -- Aristotle

_______________________________________________
NUT-devel mailing list
NUT-develmplayerhq.hu

http://lists.mplayerhq.hu/mailman/listinfo/nut-devel


  


  

    
  

  
  
   
     
    






 [1-4]











   
 





about | contact  Other archives ( Real Estate discussion Medical topics )