Gstreamer compatibility

[basheuft]

Noticed today that a number of SeekFlags in element.go (introduced by: 06dccea) are not compatible with older versions of Gstreamer (<1.18).

We need to decide which versions we are going to support.

For example, i needed to comment lines 59:62 in element.go to get it working on Gstreamer 1.14.

What do you guys think?

[coolbit-in]

I also had this problem. I want to use this package on jetson nx, but the default version of gstreamer is 1.14.5. so I use go mod vendor command to save the package in ./vendor then comment out these two lines of codes, finally run successfully.

[notedit]

@basheuft I use the latest gstreamer on my mac, you can send an pr if this confuse you.