gstreamer + pygobject problem

[Damon Lynch <damonlynch gmail com>]

Hello,

This code to extract a frame of video works some of the time, but certainly not all the time:

https://gist.github.com/damonlynch/630224ac1c472cb73bc17b260e3cc5fb

On a large number of versions of several mainstream Linux distributions, it always fails at line 31, the seek operation. I've done some testing with various distributions, and what I find puzzling is that the success / failure is not necessarily tied to the version of Gstreamer / PyGObject:

• Ubuntu 16.04: Gstreamer 1.8.3 PyGObject 3.20.0 success
• Ubuntu 16.10: Gstreamer 1.8.3 PyGObject 3.22.0. failure
• Ubuntu 17.04: Gstreamer: 1.10.4 PyGObject: 3.22.0 failure
• Ubuntu 17.10: Gstreamer: 1.12.1 PyGObject: 3.24.1 success
• Fedora 24: Gstreamer: 1.8.3 PyGObject: 3.20.1 failure
• Fedora 25: Gstreamer: 1.10.4 PyGObject: 3.22.0 failure
• Korora 25 (Fedora derivative) Gstreamer: 1.10.4 PyGObject: 3.22.0 success
• LinuxMint 18.0 Gstreamer: 1.8.3 PyGObject: 3.20.0 failure
• LinuxMint 18.1: Gstreamer: 1.8.3 PyGObject: 3.20.0 failure
• LinuxMint 18.2: Gstreamer: 1.8.3 PyGObject: 3.20.0 failure
  
• openSUSE 42.2: Gstreamer: 1.8.3 PyGObject: 3.20.1 failure
• openSUSE Tumbleweed: Gstreamer: 1.12.0 PyGObject: 3.24.1 failure
• Debian 9: Gstreamer: 1.10.4 PyGObject: 3.22.0 success

What's going on here? Can the python function be modified so that it works all the time?

Thanks.

Damon

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http://www.damonlynch.net