This is a difficult question to answer, as elaborated below. What we have said is that Dirac is comparable to H264 in quality and, in principle, is simpler to implement (therefore lower processing requirements). Comparable in quality means that it has similar quality at similar bit rates and, therefore, requires similar disk space.
Do you mean how do the current implementations of codecs compare TODAY? Or do you mean, how would mature and equally well developed codecs compare in the future? I have found that many people who ask for comparisons are not clear which question they are asking. It is, of course, reasonable to ask how the current implementations work today. However the results are not very meaningful. Dirac is less mature than H264. Consequently it is improving faster than H264. Even in the past few weeks there have been improvements in coding quality, particularly at low bit rates. Over the past few years there have been really dramatic falls in bit rate (for example the bit rate has halved over the past year). So, if you do a comparison today it will be out of date in a few weeks time. The Dirac team publicly demonstrated Dirac at the International Broadcasting Convention (IBC) in Amsterdam in September. We were showing HDTV at 6Mbit/s. Our demos where more than 10 minutes long and IBC had about 50,000 visitors from the broadcasting industry. There was nowhere to hide in terms of picture quality! But our picture quality certainly stood up to scrutiny and in my (admittedly biased) opinion the picture quality was better than the vast majority of H264 pictures on show at the same bit rate. So, at the moment, Dirac compression quality is comparable to the best H264 quality and is improving. For some content Dirac is better than H264. For some material it will be worse. But Dirac is improving more rapidly than H264. Similarly it is not very meaningful to ask about processing requirements. The Schro decoder has reasonable performance in terms of processing requirements. But we know, even following work over the past few weeks, that there are quite a few ways we can optimise processing. At the moment H264 probably has lower processing requirements. But the situation is fluid and, as for compression efficiency, Dirac is likely to improve faster than H264. Also consider whether processing in the CPU versus the GPU is an issue. At the moment Scho runs in the CPU. In the future (like some H264 implementations) Dirac will run in the GPU, which will dramatically improve performance. So at the moment I would say Dirac compression (using the Dirac research coder) is comparable to H264. The Schro encoder is not quite there yet but we are working on it an I expect it to reach similar levels of performance by the end of the year. In terms of processing requirements H264 is probably ahead at the moment. But Dirac is probably improving more quickly than H264 so the situation is moving in favour of Dirac. What of the more fundamental question about comparison of fully mature implementations of Dirac and H264? The Dirac specification may well allow Dirac to provide both better compression performance and lower processing requirements than H264 in the future. Tim Borer At 21:10 17/10/2008, Stas Oskin wrote: >Hi. > >Are there any comparison details for how Dirac compares to MP4 (the >codec) and H.264 in terms of: > >a) Processing requirements >b) Disk space requirements? > >Regards. >------------------------------------------------------------------------- >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 ------------------------------------------------------------------------- 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
