video thumbnailing slowed down by constant respawning of vs-thumb process

[Florian Boucault]

Part of the video thumbnailing being slow is due to the fact that the thumbnailing process (vs-thumb) is reforked for every video.

[Michi Henning (michihenning)]

At a guess, I don't think it would be the fork. A fork/exec on my Nexus 4 takes about 80 ms. If it takes a whole second, there is something else going on. I suspect its the actual decoding that's to blame, not the fork/exec.

[James Henstridge (jamesh)]

It likely isn't the fork/exec that is slow, but rather the initialisation of the media pipeline.

I did some significant refactoring of the vs-thumb utility in the devel branch, putting most of the logic in a ThumbnailExtractor class. That class manages the GStreamer pipeline, and could be used to thumbnail multiple files.

We'd need to change how the thumbnailing service talks with vs-thumb to take advantage of this though.

[Michi Henning (michihenning)]

The problem here is gstreamer, which is extremely slow pulling an image out of a video stream. The fork/exec itself is fast, as is transfer of the image into the cache once it has been extracted.

[PS Jenkins bot (ps-jenkins)]

Fix committed into lp:thumbnailer/devel at revision 257, scheduled for release in thumbnailer, milestone Unknown