ProcessUtils.SpawnProcess - Get StandardOutput Problem

Deadline
1

Hi all, I’m trying to write a Deadline post script that creates a mov proxy file… It’s all working well, however I’d like to add timecode from the outputed dpx files into the mov file. I can do this fine using ffmbc (a skew of ffmpeg) however in order to get the timecode from the dpx files, I need to use ImageMagick. That’s all good too, I’ve got the command to use, I can do it from within a dos window with no problems however when I try to run it from within a deadline post script I can’t capture the stdout to a variable… Here’s what I thought should work…

processDPXTimecode = ProcessUtils.SpawnProcess(imageMagickPath, imageMagickArgs) startTimecode = processDPXTimecode.StandardOutput ProcessUtils.WaitForExit( processDPXTimecode, -1 )

I’ve tried all manor of variations, changing the position of the code but I mostly get an error stating that I can’t read stdout because the process hasn’t started. Can anyone help me on this issue? As a side note, I could also write the output to a file and then read it back in, but simply putting a “>path\file.txt” inside the imageMagickArgs doesn’t actually redirect the output. Can anyone help on this issue?

Cheers, Thanks for any responses…

Adrian

2

Ok, So I’m replying to my own question…

For those who are interested, this is the work around…

p = Process() p.StartInfo.UseShellExecute = False p.StartInfo.RedirectStandardOutput = True p.StartInfo.FileName = imageMagickPath p.StartInfo.Arguments = imageMagickArgs p.Start() p.WaitForExit() startTimecode = p.StandardOutput.ReadToEnd()

As a side note… This whole venture shouldn’t be required… A bug I think exists, the following code should work but doesn’t…

processDPXTimecode = ProcessUtils.SpawnProcess(executable=imageMagickPath, arguments=imageMagickArgs, redirectStdOutput=True) ProcessUtils.WaitForExit( processDPXTimecode, -1 ) startTimecode = processDPXTimecode.StandardOutput.ReadToEnd()

An error is given regarding ‘redirectStdOutput’… This should be looked into.

Cheers!

3

Hi Adrian,

You need to use the 4th SpawnProcess function defined here:
thinkboxsoftware.com/deadlin … _Utilities

Also, I don’t think specifying the arguments as arg=value works in this case, because you’re calling .NET functions instead of native python functions.

Let us know if that helps!

  • Ryan
4

Hi Ryan, thanks for the response, I tried using the 4th spawnProcess function without luck… To be honest, I couldn’t work out how to instantiate a ‘ProcessWindowStyle’ object to feed it to the function… I’m not really a programmer more a guy who writes pretty complex scripts through trial and error! As a side note, the args=value proved to be fine, I could always get the process to run successfully, I just could not get the standard output of the process.

Cheers…

Adrian

P.S. I’m still convinced that ‘processDPXTimecode = ProcessUtils.SpawnProcess(executable=imageMagickPath, arguments=imageMagickArgs, redirectStdOutput=True)’ should work!

5

ProcessWindowStyle is a .NET enumeration from the System.Diagnostics namespace:
msdn.microsoft.com/en-us/library … style.aspx

Here is an example that should work:

from System.Diagnostics import *
from System.IO import *

...

processDPXTimecode = ProcessUtils.SpawnProcess( imageMagickPath, imageMagickArgs, Path.GetDirectoryName( imageMagickPath ), ProcessWindowStyle.Normal, True )
ProcessUtils.WaitForExit( processDPXTimecode, -1 )
startTimecode = processDPXTimecode.StandardOutput.ReadToEnd()

Hehe, then technically it wasn’t working fine. :wink:

As I mentioned previously, these are .NET functions that you are calling, not native python ones. .NET doesn’t support optional or default parameters, so I wouldn’t expect it to work when calling them from python.

Cheers,

  • Ryan