Dirac, like other codecs, specifies the bit stream and the decoder. The coder implementation is deliberately left as unconstrained as possible so that implementers can design their version with the characteristics they require. With an encoder you are typically trading off compression quality, computational power, ease of implementation, number of user settings, optimisation for particular platforms versus cross platform implementation, clarity of code, and in hardware, ease of hardware implementation, power consumption, hardware resources etc.
So each encoder is different to satisfy different requirements and constraints. But codecs are all too often judged on the compression quality, irrespective of any other factors. The design brief for the Schroedinger implementation of Dirac was to produce a multithreaded, multicore, optimised efficient, cross platform design, in C, suitable for end users. It is a big and difficult job and David Schleef has done an excellent job getting it this far. However the Schro architecture is different from Dirac-research and some development is required to achieve the same compression performance as the Dirac-research encoder (developed by the BBC). Bear in mind that the Dirac-research encoder as been under continuous development for five or more years. That doesn't mean that it will take anywhere like as long for Schro to catch up in compression performance. Some of the team here at the BBC are working on it with David Schleef. We're hoping that we can get achieve nearly the same, or even better, compression performance, than Dirac-research coder by the end of the year. We wish to do this whilst retaining the computational efficiency of Schro. Until we have got further with the work on Schro encoder it doesn't make sense to do comparative tests of compression performance with it. Until that time use the Dirac-research encoder (we are hoping to do another release in the next month). I'll ask Andrea, one of the engineers here at the BBC, to maybe outline a few of the issues that he is working on to improve Schro compression performance. Tim At 18:10 31/07/2008, Klaus Bucher wrote: >What is missing in the Schroedinger implementation compared to the BBC Dirac >codec, >not to get the same encoding quality? > >Thanks >Best regards >Klaus > >----- Original Message ----- >From: "Tim Borer" <[EMAIL PROTECTED]> >To: "Simon Wagner" <[EMAIL PROTECTED]>; ><[email protected]> >Sent: Thursday, July 24, 2008 7:48 PM >Subject: Re: [Schrodinger-devel] GST-Plugin - min-bitrate, max-bitrate and >rate-control > > > > At 16:33 22/07/2008, Simon Wagner wrote: > > >I am trying to benchmark Dirac against Theora. As source I am using the > > >first few minutes of Elephants Dream. > > > > > >I am trying to encode the video with the help of GStreamer and > > >libschroedinger. > > > > At present the encoding quality of Schroedinger is not as good as the BBC > > Dirac coder - so you will get misleading comparisions. > > > > I would suggst either using the BBC dirac encoder or waiting a few months > > until the Shro encoder catches up. > > > > Ultimately we want to move the Schro encoder - but it's not there yet. > > > > Tim Borer > > BBC Dirac Team leader > > > > > > > > ------------------------------------------------------------------------- > > 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
