OK. I'm well out of my depth, but this problem has been around too long
unfixed and it needs fixing. If I 'think out loud' here, maybe others
could chip in? Sorry this is a bit lengthy.
The problem: a video on an Impress slide starts and finishes with an
inappropriate frame displayed. I've made a series of test videos, the
frames simply containing the frame number from 0....N-1, and in a
selection of formats (.mp4, .flv and ".avi") using avconv. I then embed
that video into a slide using Insert|Audio or Video.
A placeholder frame from the video is displayed during editing. This is
a frame from within the video, but it isn't always the same one. It
depends on the length and format and frame-rate of the video. So, for
example, using 15fps, a 50-frame flv video shows the frame #24 (the 25th
frame, starting at #0), A 35-frame video shows #12, and a 25-framer
shows #0. a long mp4 shows #30, a 10-frame mp4 shows #5, with a
selection between. An avi just shows a question mark, presumably because
something can't seek into the video (supposition!).
For comparison, a 1500-frame clip at 15fps starts on frame #30; at
25fps, it starts on frame #75.
Much the same also applies to LO6's property page video preview - with
the addition that when the seek slider is tweaked, the placeholder is
also shown while the slider is being moved (it usually settles down to
show a reasonable frame, not always.)
****
The big deal-breaker is that this placeholder frame is shown during the
slide show when the slide appears and before the video plays (a long
time if there's a slow transition), and also when the video has
finished. This means at the very least an annoying flicker at the start,
and a usually totally inappropriate ending.
****
Versions don't seem important - it's been there at least since LO3, and
is still in LO6. (And, if I recall, even since OOo) FWIW I'm using 5.1.6.2
I'm using linux Mint; I can't check now, but from memory the same sort
of issue used to arise on Windows. So presumably the issue lies
somewhere in the LO source code, and not for example the gstreamer library.
So, I've been looking particularly at the avmedia directory; I have
however failed miserably to find anything at all that might relate to
the above observations. (Not helped by my decidedly dated experience of
C++ :-{ ). If anyone has any experience/knowledge/insights into
whereabouts to look, that would be great.
Sorry that's so long, but I think the symptoms need documenting
somewhere. Any thoughts at all would be most welcome - thanks.
--
Mike Scott (unet2 <at> [deletethis] scottsonline.org.uk)
Harlow Essex England
"The only way is Brexit" -- anon.
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