Re: [GM-help] gm display unrecognized command 'display'

[Bob F. <bfr...@si...>]

On Tue, 17 Nov 2015, McDowell, Blake wrote:

> Hi Bob,
>
> Thanks again for the insightful info. I didn't realize GM rewrote 
> all of the pixel data. Slow is definitely an issue with that, though 
> from an archival perspective we would have more of an issue with 
> putting the files through a whole other process - something we 
> generally like to avoid for our master files. Do you have any 
> software in mind that would perhaps be better suited for rewriting 
> DPX header data without rewriting the data? Maybe something like 
> mkvpropedit 
> (https://www.bunkus.org/videotools/mkvtoolnix/doc/mkvpropedit.html) 
> but geared toward .dpx?

I am not aware of any specific software.  DPX uses specific field 
offsets and sizes.  It is important to know if a DPX header section 
exists and the offset to the data.  If the header section does not 
exist and there is not free space for it prior to the data offset, 
then the whole file would need to be re-written.

Even a Python script could be used to update DPX file headers.

Code from GM could be re-used for this purpose (even within GM) but GM 
currently only supports reading from files, and writing files from 
scratch.  It does not currently have modes for updating an existing 
file.  If the existing coder is used, then a new interface (other than 
read/write) would need to be devised to call into it.

Since GM supports subcommands, a new subcommand for editing properties 
of an existing file could be added without disturbing the other 
commands (or existing users).

> Perhaps the GM development team is interested in having this as a GM sponsored feature?

This is certainly interesting but there is no shortage of things to 
do.  This is an area where an interested party with the capability 
could contribute.

Bob
-- 
Bob Friesenhahn
bfr...@si..., http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/