Hi Tim.
Thank you for the detailed answer.
It seems as Dirac becomes a serious contender in the codecs space, becoming
very attractive alternative to commercial codecs out there.
Regards.
2008/10/20 Tim Borer <[EMAIL PROTECTED]>
> 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 you do a comparison today it will be out of date in a few weeks time.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.
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