On Wed, Jul 29, 2020 at 10:16:33PM +0200, Marton Balint wrote: > > > > > > > > > > > if you tested with SDI with TC. > > > > > > > > > 00:00:00:24 > > > > > > > > > 00:00:00:24 > > > > > > > > > 00:00:00:00 > > > > > > > > > 00:00:00:00 > > I did tests, and depending on which timecode you select, and the timecode > formats which are available in the SDI signal, this really can be the case, > so you were right that the decklink API usually does not provide the proper > timecode as string, only the value of "raw" timecodes in the signal, > regardless of used frame rate. > > I could not test, but assume that if a high frame rate timecode is detected > then valid string timecode is returned. Otherwise max 30fps timecode. > > > > > > I have tested with bmdTimecodeFieldMark > > > > > flag, it's not set as expected for testing. I have no clue how to get > > > > > the flag as the API provide the TC string is same for the frame pair. > > > > > Maybe I miss something. > > SMPTE ST 12-2 has a good overview of the used signalling in section 7. > Basically for 50/60 fps different timecode types (VITC1, VITC2) are used for > different parity frames. > > We have to be smart here to generate proper timecode, because the decklink > API does not tell you which timecode it had found for an rp188any query... I > suggest the following: > > - If the user selects high frame rate timecode (not available as an > option at the moment, but can be added), then use that directly. > - If the user selects rp188any then > - Query high frame rate timecode, if exists use that directly. > - Otherwise > - for <= 30fps query rp188any and use that directly > - for > 30fps > - query VITC1, if exists use that with frame doubling and field flag > checking > - otherwise query VITC2, if exists use that with frame doubling > and field flag checking > - otherwise query LTC, if exists use that with frame doubling and > field flag checking > - note that this special ordering of querying the timecode types > is slightly different from what the decklink API does and it > should be mentioned in the docs. > - Otherwise > - for <= 30fps query the selected timecode and use that directly > - for > 30fps query the selected timecode and use that with frame > doubling and field flag checking The suggestion is very clear, I lacks the different TC test signal so I can't try to implement and test it yet.
> > Also probably it is better to use IDeckLinkTimecode->GetComponents() and use > av_timecode_get_smpte() instead of using the string value. Yes, the TC format is rp188any when I test, I recall I have try to get by GetComponents, the result is consistent with string() before, I'll try to retest again if I test signal is avaiable. > > Regards, > Marton > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". -- Thanks, Limin Wang _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
