Thanks Tim, certainly, all the work that has gone into SMPTE 2042 shall not be ignored. In the immediate term, I'll double check issues I found against the SMPTE to the extent that the latter covers them. I still think it's worthwhile correcting the obvious issues now, regardless of the longer term solution.
When you say include the SMPTE spec by reference, does that imply trimming the current Dirac spec of everything covered by SMPTE 2042 and adjusting the rest to be a natural extension, or are you suggesting embedding the SMPTE spec into the current Dirac document (potentially by translating the Word document to LaTeX)? Assuming the former, what are the redistribution terms of SMPTE 2042? Are the test streams freely available? Having never had any exposure to video codecs before and practically no knowledge of signal processing, I was very impressed by the completeness and quality of the Dirac spec. It enabled me to write a decoder exclusively based on the spec except for just a couple of issues that I'll bring up later (unfortunately my decoder doesn't do intra frames correctly yet). Regards, Tommy On Mar 6, 2010, at 00:47 , Tim Borer wrote: > Recent work on specification has focused on the SMPTE specification for Dirac > Pro/VC-2. VC-2 or SMPTE 2042 is the intraframe coding subset of the complete > Dirac spec. Although that may sound like a small sub-set, in fact it includes > most of the Dirac spec. It includes everything about the wavelet transform > and arithmetic coding, data types, stream syntax etc. Of course it doesn‚t > include details of the inter frame coding but that actually represents a > relatively small proportion of the spec. > > I have been working with the SMPTE on specification over the past few years. > Late last year the core part of the Dirac Pro spec SMPTE 2042-1 was ratified. > This is a one hundred and thirty odd page spec defining the core decoder. > More recently parts 2 (level specifications) and part 3 (conformance testing, > including conformance test streams) have also been ratified. So now Dirac > Pro/VC-2/SMPTE 2042 is a fully ratified international codec spec available > from the SMPTE store. In addition there are some specialised SMPTE specs > relating to specific broadcast applications. > > In considering updating the Dirac long GOP spec we need to ensure that the > SMPTE spec remains the master (as far as it goes). It would be bad if the two > specifications diverged. The SMPTE spec has been subject to considerable peer > review in the SMPTE standards committee. It has diverged from the Dirac spec > in order to correct bugs etc. It is a more reliable reference for the part of > Dirac that it covers than the Dirac spec. Of course, like all documents, it > probably still has bugs in it. I would request that if Dirac users have > queries about the Dirac spec they first check the SMPTE spec. If they could > then note and send me any errors I can get them corrigendum to the > specification. If you aren‚t able to obtain a copy of the SMPTE spec then > contact me and I will see what I can do. > > I think the long GOP Dirac spec needs redrafting so that it normatively > includes the SMPTE spec by reference. That way we can ensure that the two do > not diverge. This is quite a lot of work and, at present, the BBC is > reluctant to commit many resources, but I will see what I can do. Ideally we > would release an addition to the existing specification (SMPTE 2042 part 4?) > that includes the interframe coding specification. This is possible but, > having worked on the VC-2 spec or several years, I know that it is a lot of > work. Anyone out there willing to help? > > Please get back to me on issues of specification and standardisation. > > Best regards > > Tim Borer ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Schrodinger-devel mailing list Schrodinger-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/schrodinger-devel
