3640 Views 11 Replies Latest reply: Aug 18, 2008 10:26 PM by David M Brewer
I would say since the codec uses the name jpeg that it's lossy. Year ago when jpeg2000 came out for still images it was lossy. It's a nice codec. Better than the standard jpeg codec. But then again to get people to install it on their computer so they can view the videos/stills is another story that kills new codecs. That's why the still version not used that much, little support.
Firstly I truly appreciate all of your responses and the time you took to research them.
I take it there is no documentation available for the quicktime implementation of the JPEG 2000 codec? I could not find any either.
The specific answers I need in written documentation for a government report are this:
Is the JPEG 2000 implementation in quicktime consistent with the Motion JPEG 2000 (often referenced as MJ2 or MJP2)? It is an open ISO standard and does not employ temporal or inter-frame compression. Each frame is an independent entity encoded by either a lossy or lossless variant of JPEG 2000.
As highlighted earlier I am specifically interested in LOSSLESS compression.
Thanks again for your responses David, Klaus and Kirk but:
David your statement "I would say since the codec uses the name jpeg that it's lossy." is mostly true but this isn't always the case, please see below. Again I am looking for where the documentation is located, so I can PROVE what you are saying is correct or not.
Klaus I disagree with your statement "No jpeg compression is lossless" and one of the reference links you gave "http://en.wikipedia.org/wiki/JPEG_2000" also contradicts that statement. That is unless you specifically mean the Quicktime implementation and not jpeg in general. This is exactly the information I am trying to discern but I need documentation to substantiate it.
Kirk "Any export could introduce additional compression of your source format." This is true but not so if I export uncompressed video as uncompressed video for example. If you can point to where the documentation says the Quicktime implementation of "JPEG 2000 is an "image" format (not a video compression codec)" I would love to see it, otherwise it is just an opinion - albeit a good and very likely correct one!!!
Being a mac fanboy I WANT to employ quicktime JPEG 2000 but unless I can PROVE with documented evidence QT JPEG2000 IS lossless for government archival use, my hands are tied.
An example of a company that does use JPEG2000 lossless today is Samma Systems: http://www.sammasystems.com/
Is there written documentation that Apple's implementation of JPEG2000 is mathematically lossless or is it only visually lossless?
Apple??? ISO??? Anyone???
I've done some work with the I3A and they were heavily involved in the JPEG 2000 Standard effort.
I think the key issue is Motion JPEG 2000 doesn't use inter-frame encoding. http://www.jpeg.org/jpeg2000/j2kpart3.html lists the International Standard (ISO/IEC 15444-3) from November 2001
In the US you could get the Standard from http://www.i3a.org/resources/i3a-image-technology-standards/
Of course, none of this tells us what Apple has done in QuickTime (although they have participated in I3A standards development).
"Is the JPEG 2000 implementation in quicktime consistent with the Motion JPEG 2000 (often referenced as MJ2 or MJP2)? It is an open ISO standard and does not employ temporal or inter-frame compression. Each frame is an independent entity encoded by either a lossy or lossless variant of JPEG 2000."
It if were the same it would be named Motion-JPEG 2000, don't you think?
Where do you get your "uncompressed" video? What type of device? What type of media are the files saved to?
I did a sample export from a .dv file using JPEG 2000:
:32 file with a video track of 86.75 MB's (.dv) became a video track of 207 MB's that had a data rate of 55 mbits per second.
My 3 GHz machine could only get about 7 frames per second during playback.
Video quality was nearly identical to the source. It's not an efficient video encoder.
Thankyou Kirk, I apologise if my responses above seem disrespectful I assure you they are not.
"It if were the same it would be named Motion-JPEG 2000, don't you think?" Yes I do and I expect you are right. I was just looking for documentation to prove it one way or the other, as a government report requires proof to support the opinion etc etc.
The main difference in how my questions are framed to your last responses, is that the archive I work for is not concerned with realtime playback at all. They are only concerned with lossless preservation. It's a completely different mindset to broadcast television for example and has taken me a while to get my own head around.
FYI we have uncompressed video coming from varied sources like 2 inch reels, 1 inch, u-matic down to good old VHS and at present it is captured through two Edius (yetch!!) suites. What I would love to do is capture directly via a really high spec'd mac pro using uncompressed to transcode to jpeg2000 uncompressed or if possible with a raid array capture directly to jpeg2000 uncompressed as the capture format.
This would negate a time consuming transcode process. But I fear the QT JPEG2000 implementation does seem to be lossy and as I cant find any documentation to prove otherwise, we will have to look at other options like storing uncompressed instead. (Still using a Mac if possible) : )
nocme, here's some reading:
I'm sure Quicktime jpeg2000 is the same as above.
I think your at a point were you need to talk (write) to someone who writes these codecs. Why not write to Lead and ask them.
Or write to Square 5. They make the program MPEG-Streamclip. One of the best free non-Apple video converters. I believe he write his own codecs.
Worth a try...
Message was edited by: David M Brewer
Message was edited by: David M Brewer