Attempt to handle remaining header bytes

tja2fumen/constants.py

@@ -69,11 +69,13 @@ byte_strings = {
 
 simpleHeaders = [b * 36 for b in [byte_strings['431'], byte_strings['V1'], byte_strings['V2']]]
 
-# This sample header for the "unknown header bytes" is built from the investigations in utils/validateHeaderMetadata
+# Create a sample header pre-filled with known bytes
-# However, it's missing song-specific metadata from bytes 12, 16, 20, and (perhaps optionally), 76, 77 and 78.
 unknownHeaderSample = [0] * 80
+# The following bytes are hardcoded by tja2fumen.exe (implying they have little/no effect on how the song is parsed)
 unknownHeaderSample[4] = 16
 unknownHeaderSample[5] = 39
+unknownHeaderSample[12] = 10
+unknownHeaderSample[16] = 8
 unknownHeaderSample[21] = 255
 unknownHeaderSample[22] = 255
 unknownHeaderSample[23] = 255
@@ -89,3 +91,15 @@ unknownHeaderSample[60] = 1
 unknownHeaderSample[64] = 30
 unknownHeaderSample[68] = 30
 unknownHeaderSample[72] = 20
+unknownHeaderSample[76] = 78
+unknownHeaderSample[77] = 97
+unknownHeaderSample[78] = 188
+
+DIFFICULTY_BYTES = {
+    'Easy': [112, 23],
+    'Normal': [88, 27],
+    'Hard': [88, 27],
+    'Oni': [64, 31],
+    'Ura': [64, 31],
+    'Edit': [64, 31]
+}

tja2fumen/converters.py

@@ -1,6 +1,7 @@
 from copy import deepcopy
 
-from constants import TJA_NOTE_TYPES, unknownHeaderSample
+from utils import computeSoulGaugeByte
+from constants import TJA_NOTE_TYPES, DIFFICULTY_BYTES, unknownHeaderSample
 
 # Filler metadata that the `writeFumen` function expects
 default_note = {'type': '', 'pos': 0.0, 'item': 0, 'padding': 0.0,
@@ -101,6 +102,7 @@ def convertTJAToFumen(fumen, tja):
     currentBranch = 'normal'  # TODO: Program in branch support
     tja['measures'] = preprocessTJAMeasures(tja)
     currentDrumroll = None
+    total_notes = 0
 
     # Parse TJA measures to create converted TJA -> Fumen file
     tjaConverted = {'measures': []}
@@ -172,9 +174,11 @@ def convertTJAToFumen(fumen, tja):
                     note['hits'] = tja['metadata']['balloon'].pop(0)
                     note['hitsPadding'] = 0
                     currentDrumroll = note
+                    total_notes -= 1
                 if note['type'] in ["Drumroll", "DRUMROLL"]:
                     note['drumrollBytes'] = b'\x00\x00\x00\x00\x00\x00\x00\x00'
                     currentDrumroll = note
+                    total_notes -= 1
                 measureFumen[currentBranch][note_counter] = note
                 note_counter += 1
         measureFumen[currentBranch]['length'] = note_counter
@@ -192,7 +196,14 @@ def convertTJAToFumen(fumen, tja):
             else:
                 currentDrumroll['duration'] += measureDurationBase
 
-    tjaConverted['headerUnknown'] = b"".join(i.to_bytes(1, 'little') for i in unknownHeaderSample)
+        total_notes += note_counter
+
+    # Take a stock header metadata sample and add song-specific metadata
+    headerMetadata = unknownHeaderSample
+    headerMetadata[8] = DIFFICULTY_BYTES[tja['metadata']['course']][0]
+    headerMetadata[9] = DIFFICULTY_BYTES[tja['metadata']['course']][1]
+    headerMetadata[20] = computeSoulGaugeByte(total_notes)
+    tjaConverted['headerUnknown'] = b"".join(i.to_bytes(1, 'little') for i in headerMetadata)
     tjaConverted['order'] = '<'
     tjaConverted['length'] = len(tjaConverted['measures'])
     tjaConverted['unknownMetadata'] = 0

tja2fumen/utils.py

@@ -1,5 +1,6 @@
 import sys
 import struct
+import math
 
 from constants import simpleHeaders, byte_strings
 
@@ -190,6 +191,13 @@ def validateHeaderMetadata(headerBytes):
             assert val == 0, f"Expected 0 at position '{idx}', got '{val}' instead."
 
 
+def computeSoulGaugeByte(n_notes):
+    # I don't think this is fully accurate. It doesn't work for non-Oni songs, and it's usually off by a bit.
+    A = -85.548628
+    B = 44.780199
+    return round(A+B*math.log(n_notes))
+
+
 def readStruct(file, order, format_string, seek=None):
     """
     Interpret bytes as packed binary data.