Timecode implementation

ptulsconv/broadcast_timecode.py

@@ -0,0 +1,74 @@
+from fractions import Fraction
+import re
+import math
+import functools
+
+
+def smpte_to_frame_count(smpte_rep_string: str, frames_per_logical_second: int, drop_frame_hint=False):
+    """
+    Convert a string with a SMPTE timecode representation into a frame count.
+
+    :param smpte_rep_string: The timecode string
+    :param frames_per_logical_second: Num of frames in a logical second. This is asserted to be
+            in one of `[24,25,30,48,50,60]`
+    :param drop_frame_hint: `True` if the timecode rep is drop frame. This is ignored (and implied `True`) if
+            the last separator in the timecode string is a semicolon. This is ignored (and implied `False`) if
+            `frames_per_logical_second` is not 30 or 60.
+    :returns (frame_count, fraction): If a fractional frame is in the SMPTE string it will be returned here in the
+            `fraction` part.
+    """
+    assert frames_per_logical_second in [24, 25, 30, 48, 50, 60]
+
+    m = re.search("(\d?\d)[:;](\d\d)[:;](\d\d)([:;])(\d\d)(\.\d+)?", smpte_rep_string)
+    hh, mm, ss, sep, ff, frac = m.groups()
+    hh, mm, ss, ff = int(hh), int(mm), int(ss), int(ff)
+    if frac is not None:
+        frac = float(frac)
+
+    drop_frame = drop_frame_hint
+    if sep == ";":
+        drop_frame = True
+
+    if frames_per_logical_second not in [30, 60]:
+        drop_frame = False
+
+    raw_frames = hh * 3600 * frames_per_logical_second + mm * 60 * frames_per_logical_second + \
+                 ss * frames_per_logical_second + ff
+
+    if drop_frame is False:
+        return raw_frames, frac
+    else:
+        frames_dropped_per_inst = (frames_per_logical_second / 15)
+        mins = hh * 60 + mm
+        inst_count = mins - math.floor(mins / 10)
+        dropped_frames = frames_dropped_per_inst * inst_count
+        return raw_frames - dropped_frames, frac
+
+
+def frame_count_to_smpte(frame_count: int, frames_per_logical_second: int, drop_frame: bool = False,
+                         fractional_frame: float = None):
+    assert frames_per_logical_second in [24,25,30,48,50,60]
+    nominal_frames = frame_count
+    separator = ":"
+    if drop_frame:
+        assert frames_per_logical_second in [30, 60]
+        mins , _= divmod(nominal_frames, frames_per_logical_second * 60)
+        frames_dropped_per_inst = (frames_per_logical_second / 15)
+        inst_count = mins - math.floor(mins / 10)
+        dropped_frames = frames_dropped_per_inst * inst_count
+        nominal_frames = nominal_frames + dropped_frames
+        separator = ";"
+
+    hh, rem = divmod(nominal_frames, frames_per_logical_second * 3600)
+    mm, rem = divmod(rem, frames_per_logical_second * 60)
+    ss, ff = divmod(rem, frames_per_logical_second)
+
+    hh = hh % 24
+    if fractional_frame is not None and fractional_frame > 0:
+        return "%02i:%02i:%02i%s%02i%s" % (hh, mm, ss, separator, ff, ("%.3f" % fractional_frame)[1:])
+    else:
+        return "%02i:%02i:%02i%s%02i" % (hh, mm, ss, separator, ff)
+
+
+
+