Using os.popen3() to get binary data

[Christoph Krammer]

Hello everybody,

I need to get the different frames from a GIF image in my python
script and want to use the giftopnm program from netpbm to get the
frames and directly convert them to pnm files. I tried to use the
following code:

for image in images:
if (image[0:3] == 'GIF'):
(si, so, se) = os.popen3('gift opnm -image=all', 'b')
si.write(image)
frame = so.readlines()

But with this code the script just hangs. When I interrupt the script,
I get the following error message:
Traceback (most recent call last):
File "/home/tiger/stock-spam/scripts/all_in_one.py", line 46, in ?
frames = so.readlines()
KeyboardInterru pt
close failed: [Errno 32] Broken pipe

Can somebody tell me, which command I have to use that the pipe will
be closed when the giftopnm returns? This program just prints the
converted images to stdout and terminates.

Thanks in advance,
Christoph

[=?ISO-8859-1?Q?Thomas_Kr=FCger?=]

Re: Using os.popen3() to get binary data

Christoph Krammer schrieb:

for image in images:
if (image[0:3] == 'GIF'):
(si, so, se) = os.popen3('gift opnm -image=all', 'b')
si.write(image)
frame = so.readlines()
>
But with this code the script just hangs. When I interrupt the script,
I get the following error message:
Traceback (most recent call last):
File "/home/tiger/stock-spam/scripts/all_in_one.py", line 46, in ?
frames = so.readlines()
KeyboardInterru pt
close failed: [Errno 32] Broken pipe

Just a try: use read() instead of readlines()!

Thomas

[Christoph Krammer]

Re: Using os.popen3() to get binary data

Just got the solution...

After sending the image data with "si.write(image )", I have to close
the pipe to tell the program to convert the image with "si.close() ".
Now everything works fine.

Christoph

[MRAB]

Re: Using os.popen3() to get binary data

On Apr 6, 6:09 pm, Dennis Lee Bieber <wlfr...@ix.net com.comwrote:

On 6 Apr 2007 04:02:52 -0700, "Christoph Krammer"
<redtige...@goo glemail.comdecl aimed the following in comp.lang.pytho n:
>

Hello everybody,

>

I need to get the different frames from a GIF image in my python
script and want to use the giftopnm program from netpbm to get the
frames and directly convert them to pnm files. I tried to use the
following code:

>

for image in images:
if (image[0:3] == 'GIF'):

>
What type of data /is/ "image" that the FIRST three characters
identify the type? If it's the name of the file (I don't know what
giftopnm requires for input) I'd have expected the last three to
identify..
>

[snip]
FYI, the first 3 bytes of a GIF image are the ASCII characters "GIF".