See http://diracvideo.org/downloads/arith-speedups/arith-speedups.pdf
There is a similar simplification for renormalising the arithmetic encoder by ignoring carries and doing an overlap-and-add on all the values of LOW that have been determined. Thomas >-----Original Message----- >From: Dennis Ranke [mailto:[EMAIL PROTECTED] >Sent: 23 September 2008 10:18 >To: Thomas Davies >Cc: [email protected] >Subject: Re: [Schrodinger-devel] Some minor notes regarding >the Dirac spec, including a small performance gain in the >arithmetic decoder > >> A very serendipitous observation about AC - you're right about using >> CODE-LOW - we realised this when we started work on optimising the >> arithmetic decoder in Schro a couple of weeks ago, and this together >> with other improvements give about a 30% speed-up. We'll be >committing >> these next week I guess. > >That's great to hear. I actually was a bit surprised when I >didn't see this optimisation already in the schroedinger source. > >> I think I'll probably add this as an informative note, since a) the >> original structure corresponds to the usual description of >> renormalisation in the academic literature and b) it is the >same as in >> the SMPTE spec which is nearly ratified, and which I therefore don't >> want to change at this very late stage. It will be really useful to >> have some more implementation notes in there, though. > >That's fine, I guess, as long as it's somewhere in there. > >Another point I just remembered: >9.6.2: "Arithmetic coding is not supported on Inter pictures." >This confused me a bit. Don't Inter pictures always use >arithmetic coding? > >Regards, >Dennis > > http://www.bbc.co.uk/ This e-mail (and any attachments) is confidential and may contain personal views which are not the views of the BBC unless specifically stated. If you have received it in error, please delete it from your system. Do not use, copy or disclose the information in any way nor act in reliance on it and notify the sender immediately. Please note that the BBC monitors e-mails sent or received. Further communication will signify your consent to this. ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Schrodinger-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/schrodinger-devel
