[CinCV TNG] Preview on the editing bar not drawn properly after cut (GG Cinelerra)

Good Guy good1.2guy at gmail.com
Fri Oct 28 19:31:26 CEST 2016


I am not sure, but I think the problem you are describing is the fact that
when the timeline
canvas area is refreshed, that the details can vary.

1) sometimes, I get the impression that:
"preview is redrawn properly (instantly)"
is just wishful thinking.  It does work once in a while...

2) when a video track is redrawn, if the region on the timeline is less than
one frame width, that frame will be skipped.  I could make it draw a
partial frame instead.
This is the "preview is not redrawn" case.
If you want to see a small region, which is smaller than one frame width, I
recommend
that you zoom in (down arrow) until the region is larger than one frame.  I
will look at
changing the code to draw a frame fragment, but the additional frame
decoding will
slow down refresh (as described in below).  Sounds like a good idea.

3) when the canvas frame is redrawn, the "seek" algorithm used by ffmpeg
(in use in
your examples, but is true of virtually all codec implementations) varies
according to some context.  Mainly, the seek function works within each
codec.
Mostly it uses a bitrate to estimate a file position, seeks the input
stream to the "guess",
and begins to look for "iframes" (usually) so the picture will not appear
torn when the
data is reproduced.  The seek displacements, the iframe placements, and the
codec
complexity all conspire to make seeking slowww....  The preview is composed
of a series
of thumbnail images.  Each requires a seek, scale, and draw to be placed
into the track
preview.  A background thread "ResourceThread::run()" constantly tries to
repair the
damages done by editing in the track view.  It can take some time.
This is the "preview is redrawn (after few seconds)" case.

I am not exactly clear if this is the issue you wish to be examined.
Let me know if you have definite changes you are looking for.
BTW.  I wish the seeks would go faster too.  cin5 does attempt to add "mkr"
(marker)
index files to accelerate ffmpeg seeking, but ffmpeg is a middle-ware
library, between
high level apps like cinelerra, and low level libraries like codecs.  The
code is actually
pretty good, in my opinion.  This is the best I know of, but I am open to
suggestions.

gg





On Fri, Oct 28, 2016 at 10:32 AM, W P <BADFLAGELLO at hotmail.it> wrote:

> Hi, as per title, when I select a part of the video with the mouse and cut
> it (with "X") what I should get is that  the file gets automatically
> "glued" and the preview image matches with the video cut. However I noticed
> that this does not happen all the time. After a few trying I come to the
> conclusion that I get 3 different behaviors:
>
>
> 1) Preview is redrawn properly (instantly)
>
>
> 2) Preview is not redrawn (even after waiting)
>
>
> 3) Preview is redrawn (after few seconds)
>
>
> Any idea? I haven't understood how you can get the behavior you want, it
> just seems random:
>
>
> I attached some screenshots:
>
>
> Before Cutting:
>
>
> https://i.imgsafe.org/37d9ca7e2a.png
>
>
> After (redrawn after a few seconds):
>
>
> https://i.imgsafe.org/37d36be485.png
>
>
>
> After (incorrectly redrawn):
>
>
> https://i.imgsafe.org/37d0e9febe.png
>
>
> <https://i.imgsafe.org/37d0e9febe.png>
>
> https://i.imgsafe.org/37d5adcf58.png
>
>
> https://i.imgsafe.org/37d878ff7d.png
>
>
>
>
> _______________________________________________
> Cinelerra mailing list
> Cinelerra at lists.cinelerra-cv.org
> http://lists.cinelerra-cv.org/cgi-bin/mailman/listinfo/cinelerra
>
>
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