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 --- a/cinelerra-5.1/cinelerra/assetpopup.C +++ b/cinelerra-5.1/cinelerra/assetpopup.C @@ -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: http://www.gvgdevelopers.com/K2DevGuide/Clips2/NTSC_SD_DV25_colorbar.avi http://www.gvgdevelopers.com/K2DevGuide/Clips2/NTSC_SD_DV50_colorbar.avi http://www.gvgdevelopers.com/K2DevGuide/Clips2/NTSC_SD_DVCAM_colorbar.avi
Is the Waveform properly calibrated ?
Pierre