Not necessarily just the header info, but that would be the most obvious
thing to want to access. So, given that for me at least, OpenEXR
(the third party binding) crashes when used in Nuke, it's good to know
that your script will also do the job. But it would be a lot more
convenient for me if I just had a python module of pre-made functions
for accessing header info and other metadata that Nuke would not
normally display in the ViewMetaData node. Apparently the new PyIlmBase
is more for accessing stored matrices rather than text strings (headers
etc).
On 8 August 2012 22:52, Jimmy Christensen <[email protected]
<mailto:[email protected]>> wrote:
If you only wish to access the headers I can easily modify the
script to put them in a dict. Doesn't need to be compiled and is
easier to modify to your needs.
Best Regards
Jimmy Christensen
Developer
Ghost A/S
On 09/08/12 00:35, Michael Garrett wrote:
Cool - this was something I got working in a shell, and it would
have
been really handy directly in Nuke. I'm not sure how to point it to
Nuke's libraries but someone will...
On 8 August 2012 14:12, John RA Benson <[email protected]
<mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>> wrote:
just a side note: if you tried OpenEXR as your third party
python/exr implementation but it kept crashing nuke, try
re-compiling it with nuke's libs instead of the standard
python and
exr libs. It's pretty handy, works, and is a lot simpler
than using
struct.
exrfile = '/path/to/myexrfile.001.exr'
exrObj = OpenEXR.InputFile(exrfile)
exrHeaderDict = exrObj.header()
'compression' is a key in the exrHeaderDict
JRAB
On Aug 8, 2012, at 9:09 PM, Michael Garrett wrote:
I just found out that apparently PyIlmBase will not
allow access
to the exr header!! Hmm. Maybe in the future.
On 3 August 2012 14:33, Michael Garrett
<[email protected] <mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>__> wrote:
I just noticed the release of PyIlmBase in OpenEXR
1.7.1,
hopefully this can be folded into the compiled exr
version
that comes with Nuke.
Although I can't find any documentation yet, I
assume that
means there is some kind of function included that
will allow
the editing of exr header files and we can just
import that
module straight into Nuke. I had tried out a
similar function
a while back in the third party python/exr
implementation but
I found that the module would crash Nuke on import.
Michael
On 24 May 2012 19:01, Richard Bobo
<[email protected] <mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>> wrote:
Oops, forgot to make the menu addCommand be
"generic"…
...Should probably be something more like:
m = menubar.addMenu("Custom")
m.addCommand('EXR file compression info - from
a selected
Read node', 'exrCompressionTest()', '^+e')
Rich
On May 24, 2012, at 9:53 PM, Richard Bobo wrote:
Jimmy,
It works very well!
...Tomorrow, I'll try it on those
"renegade" Zip-16 files
that were made with the vrimg-->exr script
and see if it
works on those, too...
Here's your code with some added bits for
checking if the
user has tried to do something unexpected,
like not
select a node at all, select the wrong type
of node, or
select a Read node that's not reading an
EXR file, etc…
####____________________________________________________________________________
#### Function to test EXR file Compression
scheme...--
For init.py file...
####____________________________________________________________________________
def exrCompressionTest():
try:
n = nuke.selectedNode()
if nuke.selectedNode().Class()!='__Read' or
nuke.selectedNode() == "" :
nuke.message('No Read node selected.')
elif
os.path.splitext(nuke.__filename(nuke.selectedNode()))__[-1]!=".exr"
:
nuke.message('Selected Read is not an EXR')
else:
filePath = nuke.filename(n, nuke.REPLACE)
file = open(filePath, 'rb')
compressionTypes = ['RAW', 'RLE', 'ZIP1',
'ZIP16', 'PIZ',
'PXR24', 'B44']
compression = 0
if struct.unpack("i4", file.read(4))[0] ==
20000630:
versionFlag = struct.unpack("i4",
file.read(4))
loop = True
while loop == True:
i = 0
size = 0
headerStart = file.tell()
headerName = ""
headerType = ""
while i <= 50:
buffer = file.read(1)
if ord(buffer) == 0 and headerName == "":
nameSize = file.tell() - headerStart
file.seek(0-nameSize, 1)
headerName = file.read(nameSize)[0:-1]
if len(headerName) == 0:
loop = False
break
elif ord(buffer) == 0 and headerType == "":
nameSize = file.tell() - len(headerName)
- 1 - headerStart
file.seek(0-nameSize, 1)
headerType = file.read(nameSize)[0:-1]
headerSize = struct.unpack("i4",
file.read(4))[0]
if headerName == "compression":
compression = file.read(1)
else:
file.seek(headerSize, 1)
break
if i == 50 or headerStart > 1024:
loop = False
i=+1
compressMethod =
(compressionTypes[ord(__compression)])
print compressMethod
nuke.message('EXR compression is %s'
%(compressMethod))
except ValueError:
nuke.message('Please select a Read node...')
####____________________________________________________________________________
#### -- For menu.py file...
####____________________________________________________________________________
#### Add function that checks EXR files for
their
compression method...
m.addCommand('EXR file compression info -
from a selected
Read node', 'aw.exrCompressionTest()', '^+e')
Thanks!
Rich
Rich Bobo
Senior VFX Compositor
Mobile: (248) 840-2665
<tel:%28248%29%20840-2665> <tel:%28248%29%20840-2665>
Web: http://richbobo.com/
"The nearest way to glory -- a shortcut, as
it were -- is
to strive to be what you wish to be thought
to be."
- Socrates, quoted in Cicero, 44 BC.
On May 24, 2012, at 10:15 AM, Jimmy
Christensen wrote:
Updated. Fixed so that it doesn't just
stop after
screenWindowWidth, but actually stops
if the header
stops (or larger than 1024).
##############################__###############
import struct
n = nuke.selectedNode()
filePath = nuke.filename(n, nuke.REPLACE)
file = open(filePath, 'rb')
compressionTypes = ['RAW', 'RLE',
'ZIP1', 'ZIP16',
'PIZ', 'PXR24', 'B44']
compression = 0
if struct.unpack("i4", file.read(4))[0]
== 20000630:
versionFlag = struct.unpack("i4",
file.read(4))
loop = True
while loop == True:
i = 0
size = 0
headerStart = file.tell()
headerName = ""
headerType = ""
while i <= 50:
buffer = file.read(1)
if ord(buffer) == 0 and
headerName == "":
nameSize = file.tell() -
headerStart
file.seek(0-nameSize, 1)
headerName =
file.read(nameSize)[0:-1]
if len(headerName) == 0:
loop = False
break
elif ord(buffer) == 0 and
headerType == "":
nameSize = file.tell() -
len(headerName)
- 1 - headerStart
file.seek(0-nameSize, 1)
headerType =
file.read(nameSize)[0:-1]
headerSize =
struct.unpack("i4",
file.read(4))[0]
if headerName ==
"compression":
compression =
file.read(1)
else:
file.seek(headerSize, 1)
break
if i == 50 or headerStart >
1024:
loop = False
i=+1
print(compressionTypes[ord(__compression)])
##############################__###############
Best Regards
Jimmy Christensen
Developer
Ghost A/S
On 24/05/12 16:06, Jimmy Christensen wrote:
I also wanted to pitch in :)
It parses the file instead of just
searching. Can be
extended to check
for other stuff. Stops after the
first 1024 bytes and
after hitting the
"screenWindowWidth" header.
##############################__###############
import struct
n = nuke.selectedNode()
filePath = nuke.filename(n,
nuke.REPLACE)
file = open(filePath, 'rb')
compressionTypes = ['RAW', 'RLE',
'ZIP1', 'ZIP16',
'PIZ', 'PXR24', 'B44']
#test = file.read(4)
compression = 0
if struct.unpack("i4",
file.read(4))[0] == 20000630:
versionFlag =
struct.unpack("i4", file.read(4))
loop = True
while loop == True:
i = 0
size = 0
headerStart = file.tell()
headerName = ""
headerType = ""
while i <= 50:
buffer = file.read(1)
if ord(buffer) == 0 and
headerName == "":
nameSize =
file.tell() - headerStart
file.seek(0-nameSize, 1)
headerName =
file.read(nameSize)[0:-1]
elif ord(buffer) == 0
and headerType == "":
nameSize =
file.tell() -
len(headerName) - 1 - headerStart
file.seek(0-nameSize, 1)
headerType =
file.read(nameSize)[0:-1]
headerSize =
struct.unpack("i4",
file.read(4))[0]
if headerName ==
"compression":
compression =
file.read(1)
else:
file.seek(headerSize, 1)
if headerName ==
"screenWindowWidth":
loop = False
break
if i == 50 or
headerStart > 1024:
loop = False
i=+1
print(compressionTypes[ord(__compression)])
##############################__###############
Best Regards
Jimmy Christensen
Developer
Ghost A/S
On 23/05/12 01:28, Adrian Baltowski
wrote:
Hi
In fact each channel name in
exr can be 31 bytes long,
so even 4096
could be too less in some
extreme cases. On the other
side we don't
want to read too much.
The code below fix this issue:
I did small
modifications to read
actual size of channels list
and skip over, no matter
how many
channels is in the file. I
added few comments to clarify.
########################
import struct
compList = ['None', 'RLE',
'ZIP', 'ZIP 16 lines',
'PIZ', 'PXR24',
'B44', 'B44A']
n = nuke.selectedNode()
file = nuke.filename(n,
nuke.REPLACE)
fd = open(file, 'rb')
# read small portion of data
header = fd.read(256)
# search for channels list tag.
Well... in fact we
could hardcode this
position but I prefer to write
it more flexible
channels = header.find('channels')
# skip the tags...
fd.seek(channels+16)
# ...and read the actual size
of channels list. We
know, that it's
4-byte integer
channelsSize = fd.read(4)
# Ok, so we know how long (in
bytes) is the channels
list in our file.
And we simply jump over
fd.seek(struct.unpack('i',
channelsSize)[0], 1)
# Here we are
position = fd.tell()
# read next portion of data and
search for compression
header = fd.read(256)
index = header.find('compression')
fd.seek(position + index+28)
comp = ord(fd.read(1))
print compList[comp]
##############################__########
Best
Adrian
Nathan,
Thanks for the PDF link to
the OpenEXR file layout -
I was looking
for something like that!
Rich
On May 22, 2012, at 1:23
PM, Nathan Rusch wrote:
The compression
attribute will be in a different
place within the
header depending on the
number of channels in the
file (due to the
layout of the EXR header).
Adrian's snippet is
simply finding the 'compression'
attribute name
within the header,
since that is one of the standard
EXR attributes.
>From there, based on
known information about the
EXR file layout, he
can determine where the
actual compression attribute
value is stored.
The read size of 1024
is pretty much an arbitrary
value; you may
need to read a larger
chunk in order to get far
enough into the file
to locate the
compression attribute if your file has
a lot of
channels. If you know
the names of all the channels
within the file,
you could figure out
exactly how many bytes to read,
or even start
your read from a
predefined offset to keep your data
buffer as small
as possible; otherwise,
you'll just need to make a
safe estimate.
Check out this doc for
a nice simple example of the
structure of an
EXR file:
http://www.openexr.com/__openexrfilelayout.pdf
<http://www.openexr.com/openexrfilelayout.pdf>
Hope this helps.
-Nathan
-----Original
Message----- From: Dan Rosen
Sent: Tuesday, May 22,
2012 9:59 AM
To: Nuke user discussion
Subject: Re:
[Nuke-users] How to check zip
compression type for EXR
images...?
This is great! Can you
let us know what index number
the datatype is
in? I'm finding it hard
to tell.
thx
Dan
On Mon, May 21, 2012 at
7:30 PM, Richard Bobo
<[email protected]
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>> wrote:
Adrian,
Brilliant - I'll be
making it into a nice little
pulldown menu utility
function! And,
looking a bit deeper at your code,
of course, so I
can learn
some more Python...
8^)
Thanks!
Rich
Rich Bobo
Senior VFX Compositor
Mobile: (248)
840-2665
<tel:%28248%29%20840-2665>
<tel:%28248%29%20840-2665>
Web:
http://richbobo.com/
"Man has been
endowed with reason, with the power
to create, so
that he can
add to what he's
been given."
- Anton Chekhov
On May 21, 2012, at
6:40 PM, Adrian Baltowski wrote:
Hi
With just few lines
of code and totally simplified
******************************__****
compList = ['None',
'RLE', 'ZIP', 'ZIP 16 lines',
'PIZ', 'PXR24',
'B44',
'B44A']
n = nuke.selectedNode()
file =
nuke.filename(n, nuke.REPLACE)
fd = open(file, 'rb')
header = fd.read(1024)
index =
header.find('compression')
comp
=ord(header[(index+28):(index+__29)])
print compList[comp]
******************************__*****
Each exr file MUST
have compression info in the
header and this
info is
placed just after
channels info. It's simple to get
actual size of
channels
list but I quickly
set 1024 bytes of a headroom.
Best
Adrian
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