io_scene_fbx/fbx_utils.py

@@ -23,6 +23,7 @@ from . import encode_bin, data_types
 
 # "Constants"
 FBX_VERSION = 7400
+# 1004 adds use of "OtherFlags"->"TCDefinition" to control the FBX_KTIME opt-in in FBX version 7700.
 FBX_HEADER_VERSION = 1003
 FBX_SCENEINFO_VERSION = 100
 FBX_TEMPLATES_VERSION = 100
@@ -54,7 +55,19 @@ FBX_ANIM_KEY_VERSION = 4008
 FBX_NAME_CLASS_SEP = b"\x00\x01"
 FBX_ANIM_PROPSGROUP_NAME = "d"
 
-FBX_KTIME = 46186158000  # This is the number of "ktimes" in one second (yep, precision over the nanosecond...)
+FBX_KTIME_V7 = 46186158000  # This is the number of "ktimes" in one second (yep, precision over the nanosecond...)
+# FBX 2019.5 (FBX version 7700) changed the number of "ktimes" per second, however, the new value is opt-in until FBX
+# version 8000 where it will probably become opt-out.
+FBX_KTIME_V8 = 141120000
+# To explicitly use the V7 value in FBX versions 7700-7XXX: fbx_root->"FBXHeaderExtension"->"OtherFlags"->"TCDefinition"
+# is set to 127.
+# To opt in to the V8 value in FBX version 7700-7XXX: "TCDefinition" is set to 0.
+FBX_TIMECODE_DEFINITION_TO_KTIME_PER_SECOND = {
+    0: FBX_KTIME_V8,
+    127: FBX_KTIME_V7,
+}
+# The "ktimes" per second for Blender exported FBX is constant because the exported `FBX_VERSION` is constant.
+FBX_KTIME = FBX_KTIME_V8 if FBX_VERSION >= 8000 else FBX_KTIME_V7
 
 
 MAT_CONVERT_LIGHT = Matrix.Rotation(math.pi / 2.0, 4, 'X')  # Blender is -Z, FBX is -Y.
@@ -216,7 +229,7 @@ UNITS = {
     "degree": 360.0,
     "radian": math.pi * 2.0,
     "second": 1.0,  # Ref unit!
-    "ktime": FBX_KTIME,
+    "ktime": FBX_KTIME,  # For export use only because the imported "ktimes" per second may vary.
 }
 
 

io_scene_fbx/import_fbx.py

@@ -48,6 +48,9 @@ from .fbx_utils import (
     MESH_ATTRIBUTE_SHARP_FACE,
     MESH_ATTRIBUTE_SHARP_EDGE,
     expand_shape_key_range,
+    FBX_KTIME_V7,
+    FBX_KTIME_V8,
+    FBX_TIMECODE_DEFINITION_TO_KTIME_PER_SECOND,
 )
 
 LINEAR_INTERPOLATION_VALUE = bpy.types.Keyframe.bl_rna.properties['interpolation'].enum_items['LINEAR'].value
@@ -803,9 +806,8 @@ def blen_read_invalid_animation_curve(key_times, key_values):
     return key_times, key_values
 
 
-def _convert_fbx_time_to_blender_time(key_times, blen_start_offset, fbx_start_offset, fps):
+def _convert_fbx_time_to_blender_time(key_times, blen_start_offset, fbx_start_offset, fps, fbx_ktime):
-    from .fbx_utils import FBX_KTIME
+    timefac = fps / fbx_ktime
-    timefac = fps / FBX_KTIME
 
     # Convert from FBX timing to Blender timing.
     # Cannot subtract in-place because key_times could be read directly from FBX and could be used by multiple Actions.
@@ -838,19 +840,21 @@ def blen_read_animation_curve(fbx_curve):
         return blen_read_invalid_animation_curve(key_times, key_values)
 
 
-def blen_store_keyframes(fbx_key_times, blen_fcurve, key_values, blen_start_offset, fps, fbx_start_offset=0):
+def blen_store_keyframes(fbx_key_times, blen_fcurve, key_values, blen_start_offset, fps, fbx_ktime, fbx_start_offset=0):
     """Set all keyframe times and values for a newly created FCurve.
     Linear interpolation is currently assumed.
 
     This is a convenience function for calling blen_store_keyframes_multi with only a single fcurve and values array."""
-    blen_store_keyframes_multi(fbx_key_times, [(blen_fcurve, key_values)], blen_start_offset, fps, fbx_start_offset)
+    blen_store_keyframes_multi(fbx_key_times, [(blen_fcurve, key_values)], blen_start_offset, fps, fbx_ktime,
+                               fbx_start_offset)
 
 
-def blen_store_keyframes_multi(fbx_key_times, fcurve_and_key_values_pairs, blen_start_offset, fps, fbx_start_offset=0):
+def blen_store_keyframes_multi(fbx_key_times, fcurve_and_key_values_pairs, blen_start_offset, fps, fbx_ktime,
+                               fbx_start_offset=0):
     """Set all keyframe times and values for multiple pairs of newly created FCurves and keyframe values arrays, where
     each pair has the same keyframe times.
     Linear interpolation is currently assumed."""
-    bl_key_times = _convert_fbx_time_to_blender_time(fbx_key_times, blen_start_offset, fbx_start_offset, fps)
+    bl_key_times = _convert_fbx_time_to_blender_time(fbx_key_times, blen_start_offset, fbx_start_offset, fps, fbx_ktime)
     num_keys = len(bl_key_times)
 
     # Compatible with C float type
@@ -883,7 +887,8 @@ def blen_store_keyframes_multi(fbx_key_times, fcurve_and_key_values_pairs, blen_
         blen_fcurve.update()
 
 
-def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset, global_scale, shape_key_deforms):
+def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset, global_scale, shape_key_deforms,
+                                     fbx_ktime):
     """
     'Bake' loc/rot/scale into the action,
     taking any pre_ and post_ matrix into account to transform from fbx into blender space.
@@ -947,7 +952,7 @@ def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset, glo
                 assert(channel in {0, 1, 2})
                 blen_curve = blen_curves[channel]
                 fbx_key_times, values = blen_read_animation_curve(curve)
-                blen_store_keyframes(fbx_key_times, blen_curve, values, anim_offset, fps)
+                blen_store_keyframes(fbx_key_times, blen_curve, values, anim_offset, fps, fbx_ktime)
 
     elif isinstance(item, ShapeKey):
         deform_values = shape_key_deforms.setdefault(item, [])
@@ -960,7 +965,7 @@ def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset, glo
                 fbx_key_times, values = blen_read_animation_curve(curve)
                 # A fully activated shape key in FBX DeformPercent is 100.0 whereas it is 1.0 in Blender.
                 values = values / 100.0
-                blen_store_keyframes(fbx_key_times, blen_curve, values, anim_offset, fps)
+                blen_store_keyframes(fbx_key_times, blen_curve, values, anim_offset, fps, fbx_ktime)
 
                 # Store the minimum and maximum shape key values, so that the shape key's slider range can be expanded
                 # if necessary after reading all animations.
@@ -981,7 +986,7 @@ def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset, glo
                     # Remap the imported values from FBX to Blender.
                     values = values / 1000.0
                     values *= global_scale
-                blen_store_keyframes(fbx_key_times, blen_curve, values, anim_offset, fps)
+                blen_store_keyframes(fbx_key_times, blen_curve, values, anim_offset, fps, fbx_ktime)
 
     else:  # Object or PoseBone:
         transform_data = item.fbx_transform_data
@@ -1042,10 +1047,10 @@ def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset, glo
 
         # Each channel has the same keyframe times, so the combined times can be passed once along with all the curves
         # and values arrays.
-        blen_store_keyframes_multi(combined_fbx_times, zip(blen_curves, channel_values), anim_offset, fps)
+        blen_store_keyframes_multi(combined_fbx_times, zip(blen_curves, channel_values), anim_offset, fps, fbx_ktime)
 
 
-def blen_read_animations(fbx_tmpl_astack, fbx_tmpl_alayer, stacks, scene, anim_offset, global_scale):
+def blen_read_animations(fbx_tmpl_astack, fbx_tmpl_alayer, stacks, scene, anim_offset, global_scale, fbx_ktime):
     """
     Recreate an action per stack/layer/object combinations.
     Only the first found action is linked to objects, more complex setups are not handled,
@@ -1092,7 +1097,7 @@ def blen_read_animations(fbx_tmpl_astack, fbx_tmpl_alayer, stacks, scene, anim_o
                     id_data.animation_data.action = action
                 # And actually populate the action!
                 blen_read_animations_action_item(action, item, cnodes, scene.render.fps, anim_offset, global_scale,
-                                                 shape_key_values)
+                                                 shape_key_values, fbx_ktime)
 
     # If the minimum/maximum animated value is outside the slider range of the shape key, attempt to expand the slider
     # range until the animated range fits and has extra room to be decreased or increased further.
@@ -3620,6 +3625,21 @@ def load(operator, context, filepath="",
 
         # Animation!
         def _():
+            # Find the number of "ktimes" per second for this file.
+            # Start with the default for this FBX version.
+            fbx_ktime = FBX_KTIME_V8 if version >= 8000 else FBX_KTIME_V7
+            # Try to find the value of the nested elem_root->'FBXHeaderExtension'->'OtherFlags'->'TCDefinition' element
+            # and look up the "ktimes" per second for its value.
+            if header := elem_find_first(elem_root, b'FBXHeaderExtension'):
+                # The header version that added TCDefinition support is 1004.
+                if elem_prop_first(elem_find_first(header, b'FBXHeaderVersion'), default=0) >= 1004:
+                    if other_flags := elem_find_first(header, b'OtherFlags'):
+                        if timecode_definition := elem_find_first(other_flags, b'TCDefinition'):
+                            timecode_definition_value = elem_prop_first(timecode_definition)
+                            # If its value is unknown or missing, default to FBX_KTIME_V8.
+                            fbx_ktime = FBX_TIMECODE_DEFINITION_TO_KTIME_PER_SECOND.get(timecode_definition_value,
+                                                                                        FBX_KTIME_V8)
+
             fbx_tmpl_astack = fbx_template_get((b'AnimationStack', b'FbxAnimStack'))
             fbx_tmpl_alayer = fbx_template_get((b'AnimationLayer', b'FbxAnimLayer'))
             stacks = {}
@@ -3733,7 +3753,8 @@ def load(operator, context, filepath="",
                     curvenodes[acn_uuid][ac_uuid] = (fbx_acitem, channel)
 
             # And now that we have sorted all this, apply animations!
-            blen_read_animations(fbx_tmpl_astack, fbx_tmpl_alayer, stacks, scene, settings.anim_offset, global_scale)
+            blen_read_animations(fbx_tmpl_astack, fbx_tmpl_alayer, stacks, scene, settings.anim_offset, global_scale,
+                                 fbx_ktime)
 
         _(); del _