6.0.0 video thumbnailer...

[Gilles Caulier]

Hi all,

Since i written the FFMPEG video metadata parser in 6.0.0 branch, i'm
trying to register a huge video collection from my host computer.

Here, more than 2500 MKV files are present, plus a lots of MP4, MOV, and
another media taken with cellular and camera.

The registration have been very fast. 2500 file parsed in 2 minutes and
ready to use. System has SSD, Sqlite, 8 cores, and 32Gb of RAM. No crash
all work fine... excepted... the video thumbnails.

I facing random dysfunctions with video files. Sometime thumbs are there,
sometime not. Using F5 always give a different results until i try to
insist and i can see the DB locked and revival...

The video thumbnailer is based on QtAV frame extractor. My QtAV is last
stable 1.12.0. I suspect a bug somewhere in QtAV, as i can see thumbnailer
code including a lots of mutex to prevent concurrency.

This is typically abnormal. FFMPEG API is re-entrant as i checked with the
multi-threaded metadata parser unit test.

As we depend now directly of FFMPEG API, I propose to rewrite the video
thumbnailer with libav C function.

We have code ready to use with ffmpeg API here :

https://cgit.kde.org/ffmpegthumbs.git/tree/

Your viewpoint ?

Gilles
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