6 ms·
JPEG-2000 exists, but decoding is still too slow to be useful. http://en.wikipedia.org/wiki/JPEG_2000 http://en.wikipedia.org/wiki/JPEG_2000
by cjensen 13y ago
JPEG-2000 exists, but decoding is still too slow to be useful.
http://en.wikipedia.org/wiki/JPEG_2000 http://en.wikipedia.org/wiki/JPEG_2000
- wmf 13y agoWhat, it takes 2 ms instead of 1?
- acdha 13y agoMore like 500-2000ms - there are a few commercial codecs (Kakadu - as licensed in OS X, Aware) which are well-polished but the open-source situation was wretched for many years, relying on a few libraries which were indifferently maintained and seriously unoptimized. This meant that there were many valid files which could not be opened, key features like tiled decoding weren't supported and everything is so much slower that users will comment on how much longer it takes simply to open or convert a file. There is some good news in that OpenJPEG (http://www.openjpeg.org/ http://www.openjpeg.org/) has been making significant progress in recent years and is now on track to become an official reference implementation: https://groups.google.com/d/msg/openjpeg/OMc40gUsBIw/UM1ggXkii3EJ https://groups.google.com/d/msg/openjpeg/OMc40gUsBIw/UM1ggXk... Hopefully this will also translate into continued performance work and robustness testing, which would mean potential hope for a browser other than Safari to add native support: https://bugzilla.mozilla.org/show_bug.cgi?id=36351#c120 https://bugzilla.mozilla.org/show_bug.cgi?id=36351#c120
- makomk 13y agoFunny story actually - OpenJPEG got a whole bunch of optimisation a few years back because Second Life relies on JPEG2000, after having been generally neglected for some time.
- acdha 13y agoYes - that was when I started looking at it more seriously. I'm hoping that work continues after the feature support is considered mature enough.
- porker 13y agoI wondered what had happened to it, thanks for the link. Now it's over a decade old...
- jfb 13y agoSeen a movie in the theater recently? JP2k lives on in the DCI [1]. [1] http://www.dcimovies.com http://www.dcimovies.com
- cjensen 13y agoYep. Theater projectors have roughly $1k in specialized decoding chips to make that work. Software encode/decode of JP2k is the hard part. That's why there's little adoption of J2k outside of hardware solutions.
- jfb 13y agoIt's a really weird place to use JP2K -- they're functionally not space limited, or compute limited, so what's the advantage of wavelets? You could just gzip V210 or something.
- mark-r 13y agoAccording to Wikipedia they squeeze 36 bits/pixel down to 4.71 bits/pixel for a 2K 24FPS movie. That's over 7x - gzip would be hard pressed to get up to 2x. I'm sure part of the reason they need compression is to send the data over the wire rather than shipping physical media all the time. [1] http://en.wikipedia.org/wiki/Digital_Cinema_Initiatives#Image_and_audio_capability_overview http://en.wikipedia.org/wiki/Digital_Cinema_Initiatives#Imag...
- yuhong 13y agoI believe that typically DCP movies are delivered via hard drive or satellite.
- e12e 13y agoOne of the benefits is that ingestion is flexible -- In general movies can be distributed via broadband (well in advance of release too, as the files are unplayable without decryption keys). For stuff like film festivals there's usually crates and crates of HDs :-)