> On Jun 27, 2015, at 3:47 AM, Paul B Mahol <one...@gmail.com> wrote: > > Dana 26. 6. 2015. 21:26 osoba "Dave Rice" <d...@dericed.com> napisala je: >> >> Hi, >> >>> On Jun 26, 2015, at 11:27 AM, Paul B Mahol <one...@gmail.com> wrote: >>> >>> Signed-off-by: Paul B Mahol <one...@gmail.com> >>> --- >>> Waiting for comments and flames. >> >> Here are some comments and flames: >> >> I noticed that when I set min to a value greater than max. I get a crash > with "Bus error: 10". > > Good catch, I forgot about checking this. > >> >> There may be an issue with negative values for min/max. When I run: >> ffplay -f lavfi -i color=gray -vf > signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255 >> I see a line scroll across the center of the window. When I change min to > -255 I see a line at ~3/4 down the frame, where I would expect -128 to be. > Does the min and max expect non-negative numbers. >> > > It is, but it doesn't draw what you expect. It should start from middle and > either go up or down.
Not sure I understand ‘start from the middle’ vs min/max. Can you clarify in the documentation. >> It could be helpful to include equations within foreground, such as: >> ffplay -i movie.mkv -vf > "signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255:foreground=if(gt(lavfi.signalstats.YAVG\,128)\,green\,red)" >> or actually I could probably subsequently use geq to accomplish that. > > Will do, filter does not redraw whole frame it just updates columns so > different colors for bars/dots make sense in special scenarios. Updating columns (as opposed to whole frame redraw) was what I was imagining. This would be helpful for showing when a value crosses a particular threshold. > I planned to do multiple graphs for multiple metadata but perhaps it is > better to call filter multiple times and then blend frames together… Yes, I was thinking of asking for that in a comment earlier but also thought calling it multiple times would be better. In many cases one may need different min/max values and it’s likely one would be different foreground values per value, so I think multiple calls would be fine. >> Can you alias 's' for 'size' as many of the other filters do. > Will do. > >> >> This is very helpful, thanks! > > Do you have some other interesting idea worth implementing in filter I'm > listening. This drawgraph filter seems like a good way to incorporate features I normal pull from QCTools (http://bavc.org/qctools, http://github.com/bavc/qctools) into a player. In particular I’d like to use drawgraph when running video digitization processes from tape. Currently when going tape-to-file I use a filterchain like this https://github.com/amiaopensource/vrecord/blob/master/vrecord#L219-L256 to show the video with a waveform and vectorscope. I think a flaw in this type of monitoring during digitization is that the user can only observe the current frame. So if something is seen in the corner of the eye (like a tape glitch, SDI spike, quick head clog) the user doesn’t have a chance to review that until the capture is done. With drawgraph incorporated in this the last X seconds of video could be summarized through signalstats data. Thanks! Dave >> Dave >> >> _______________________________________________ >> ffmpeg-devel mailing list >> ffmpeg-devel@ffmpeg.org >> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
