[Cin] Is the Waveform properly calibrated ?
randrianasulu at gmail.com
Fri Nov 20 00:47:19 CET 2020
В сообщении от Friday 20 November 2020 01:51:29 Pierre autourduglobe via Cin написал(а):
> When I analyze a sequence of SMPT ntsc SD color bars generated by my DV
> camera. The Waveform correctly indicates that the black bands are at 7.5
> IRE but places the white band at around 92 IRE instead of 100 IRE and
> the colored bands around 70 IRE instead of 75 IRE...
> This in a project in DV ntsc YUV 720x480 format with the preferences
> "YUV colors space" to BT601 and "YUV color range" to JPEG.
> If you choose instead the preference "YUV color range" in MPEG, the
> white band is correctly at 100 IRE and the colored bands are 75 IRE,
> but... the black bands are now wrongly at 0 IRE...
Unfortunately I don't even know off-head what IRE mean in this context ... :(
But yes, there is possibility some settings not applied uniformely
(because whole jpeg/mpeg thing was implemented relatively lately in Cin's life)
You might try other Cin forks and see if they behave correctly...
I on mu side have some sad reincarnation of now-closed bug about inconsistent frame in compositor.
I was trying to make screenshot of exact (timecoded) frame , and ...I never figured out seqyence of actions
(play, seek, framestep) to get my exact frame. It often works OK initially, but after just few seeks
around it become off-by-one (usually one frame behind), and sometimes it return back to consisten state
(I look at bottom of main window for hh:mm:ss.frames reading ... and I added this patch to assetpopup.C:
diff --git a/cinelerra-5.1/cinelerra/assetpopup.C b/cinelerra-5.1/cinelerra/assetpopup.C
index b414455c..915f3b63 100644
@@ -959,6 +959,7 @@ int SnapshotMenuItem::handle_event()
double position = edl->local_session->get_selectionstart(1);
int64_t source_position = (int64_t)(position * edl->get_frame_rate());
+ printf("source_position from snapshot: %i \n", source_position);
ret = !render_engine.vrender ? 1 :
render_engine.vrender->process_buffer(frame, source_position, 0);
if( !ret )
it prints frame number each time I try to use snapshot function ....
I see Cin uses LocalSession::get_selectionstart(int highlight_only) in localsession.C and then
/searching for keyword 'position'/ mwindow->edl->align_to_frame . Not sure, may be those two
actually round things slightly differently? But I tried to use align_to_frame in this screenshot function
and it was consistently in step with original method ...in the wrong cases too!
I haven't tried render one frame yet, but I had problem seeing (and rendering!)
very first timecode "...21" on this dvcam video I tried to use to check interlaced
encoding .. :/ I tried to set in/out points by seeking to very beginning and framestepping,
and by mouse selection ... I sometimes see first frame flashing if I do play
backward - but render still starts from "...22"!
> So no possibility to have a good reading.
> This is true whether I use the X11-OpenGL video driver or just X11.
> I got the same results (problems) using the color bar from the Grass
> Valley site:
> Is the Waveform properly calibrated ?
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