[Tig] ASC CDL in the DPX header
bfriesen at simple.dallas.tx.us
Wed Oct 7 21:11:51 BST 2009
On Wed, 7 Oct 2009, Jeff Christopherson wrote:
> I had always thought it a good idea that every system processing a DPX image
> would somehow make a record of it in the header, appending it to any metadata
> concerning previous processing. Something analogous to the papers that travel
> in film cans.
> The data need not be great - just a tag with the application name, version,
> some text about the manipulations done and the date. 1KB per process would be
> overkill, I think. The file spec reserves 1MB of header space for "User
> defined data" and some other header sections have space "reserved for future
> use". While a SMPTE revision would be great, this kind of record keeping is
> currently possible if there was cooperation in the industry. In fact, the
> file spec states that the user defined data can be used for "... processing
> logs, etc.".
This seems like an interesting idea. The required user space should
be reserved in advance so that it is still possible to update the user
space or pixels without re-writing the whole file. Of course, a log
file could be maintained alongside the DPX file.
There seems to be considerable usage of the user area already. Some
people are putting audio in there. Others are adding a complex
metadata chunk which is capable of storing arbitrary metadata.
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
More information about the Tig