On Sat, 12 Sep 2020, Marton Balint wrote:
On Sat, 5 Sep 2020, Marton Balint wrote:
SMPTE 12M timecode can only count frames up to 39, because the
tens-of-frames
value is stored in 2 bit. In order to resolve this 50/60 fps SMPTE timecode
is
using the field bit (which is the same bit as the phase correction bit) to
signal the least significant bit of a 50/60 fps timecode. See SMPTE ST
12-1:2014 section 12.1.
Therefore we slightly change the format of the return value of
av_timecode_get_smpte_from_framenum and AV_FRAME_DATA_S12M_TIMECODE and
start
using the previously unused Phase Correction bit as Field bit. (As the
SMPTE
standard suggests)
We add 50/60 fps support to av_timecode_get_smpte_from_framenum by calling
the
recently added av_timecode_get_smpte function in it which already handles
this
properly.
This change affects the decklink indev and the DV and MXF muxers. MXF has
no
fate test for 50/60fps content, DV does, therefore the changes.
MediaInfo (a recent version) confirms that half-frame timecode must be
inserted
to DV. MXFInspect confirms valid timecode insertion to the System Item of
MXF
files. For MXF, also see EBU R122.
Note that for DV the field flag is not used because in the HDV specs (SMPTE
370M) it is still defined as biphase mark polarity correction flag. So it
should not matter that the DV muxer overrides the field bit.
Will apply the series soon.
Applied.
Regards,
Marton
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