[MPlayer-dev-eng] The NUT backward pointers

D Richard Felker III dalias at aerifal.cx
Mon Apr 12 18:46:25 CEST 2004


On Mon, Apr 12, 2004 at 06:10:38PM +0300, Ville Saari wrote:
> What if the nut packet header were split in two so that the backward
> pointer is stored at the end of the previous packet instead?
> 
> If bitstream is examined at the middle of the file, only the order of
> the forward and backward pointers would change. However the unnecessary
> backward pointer at the beginning of the file would be eliminated and
> and extra backward pointer would be added at the end of file which would
> make the end of file a possible point to catch the sync from.
> 
> A packet in the current specification is like:
> 
>   size of packet n
>   size of packet n-1
>   data of packet n
> 
> And the change I'm proposing would turn it into:
> 
>   size of packet n
>   data of packet n
>   size of packet n

Michael would have to comment. I'm not sure what all the implications
of this change would be, especially with type-0 frames.

> So we can see that the packet would be completely self-contained. No
> information about other packets would be needed while constructing it
> and "cat file1 file2" would produce a perfectly legal nut file if the
> files are otherwise compatible.

No, it will not be legal unless the timestamps for the second file
begin after the last timestamp for the first. Nut files absolutely
MUST NOT contain non-monotone timestamps.

Rich




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