On Mon, Nov 1, 2010 at 7:30 AM, Tim Borer <tim.bo...@bbc.co.uk> wrote: > Hi, > > I would be interested to hear the results of experiments comparing Dirac Pro > and J2K. I assume you will be comparing Intra Dirac, i.e. Dirac Pro/SMPTE > VC-2, with J2K? > > As you say Dirac Pro's entropy modelling is quite different to J2K. I doubt > it yields a higher compression ratio - the objective with Dirac Pro was to > produce a simpler, less complex solution rather than a higher compression > ratio. However I would add that, because Dirac Pro takes care to preserve > the DC precision it can have fewer visual artefacts than J2k (even if PSNR > figures don't show this). I say this because we have noticed that J2K, used > for video, can produce an annoying DC flicker even at quite low compression > ratios. > > I did some (unpublished) experiments a few years ago comparing J2K and Dirac > Pro. With arithmetic coding enabled the compression efficiency (for lossless > coding) was almost identical for the two codecs (some images were 1 or 2% > better with one codec and the other way round for other images). > Interestingly when arithmetic coding was disabled, so that entropy coding > was only the fixed variable length coding (interleaved exp-Golomb), the > compression efficiency of Dirac Pro only dropped by 20%. That is for > lossless coding arithmetic coding only appeared to give a compression gain > of 1.25. Given that arithmetic coding adds significantly to the complexity > of the codec some applications may prefer the option of not using arithmetic > coding in Dirac Pro for lower complexity at the expense of slightly reduced > compression. > > At the moment there are low delay profile hardware implementations of Dirac > Pro/SMPTE VC-2 available from Numedia Technology and from Westwood Rock. > Software implementations are available in the Open Source Schroedinger > software and from Entropy Wave. > > Regards > > Tim > > Dr Tim Borer > Lead Engineer > BBC Research & Development > BBC Centre House > 56 Wood Lane > London W12 7SB >
Hi Tim, Glad to hear somebody is actively working with dirac. I got the impression when I was rewriting the ogg/dirac demuxers for LiVES and VLC that nobody was really using the dirac format any more. Regards, Salsaman. http://lives.sourceforge.net https://www.ohloh.net/accounts/salsaman http://lives.sourceforge.net https://www.ohloh.net/accounts/salsaman > At 20:46 30/10/2010, javasharp...@ukr.net wrote: > > Hi, > > I want to do some experiments with dirac and j2k and I have a question. As I > see dirac's entropy modelling is totally different from that of j2k. It > would be interesting to know the rationale behind it. In particular if the > j2k's entropy modelling (together with the dirac's arithmetic encoder which > as I understans is more effective than j2k's quasi-arithmetic encoder) what > size decrease can be expected? > > Thanks in advance, > Vladimir > > > ------------------------------------------------------------------------------ > Nokia and AT&T present the 2010 Calling All Innovators-North America contest > Create new apps & games for the Nokia N8 for consumers in U.S. and Canada > $10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing > Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store > http://p.sf.net/sfu/nokia-dev2dev > _______________________________________________ > Schrodinger-devel mailing list > Schrodinger-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/schrodinger-devel > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 9.0.864 / Virus Database: 271.1.1/3225 - Release Date: 10/28/10 > 18:34:00 > > ------------------------------------------------------------------------------ > Nokia and AT&T present the 2010 Calling All Innovators-North America contest > Create new apps & games for the Nokia N8 for consumers in U.S. and Canada > $10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing > Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store > http://p.sf.net/sfu/nokia-dev2dev > _______________________________________________ > Schrodinger-devel mailing list > Schrodinger-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/schrodinger-devel > > ------------------------------------------------------------------------------ Nokia and AT&T present the 2010 Calling All Innovators-North America contest Create new apps & games for the Nokia N8 for consumers in U.S. and Canada $10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store http://p.sf.net/sfu/nokia-dev2dev _______________________________________________ Schrodinger-devel mailing list Schrodinger-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/schrodinger-devel
