Initial commit

ackit/convert.py

@@ -0,0 +1,56 @@
+"""WEM <-> Ogg Vorbis conversion using the game's codebook library."""
+from .codebooks import CodebookLibrary
+from .ogg import OggWriter
+from .wem import Wem
+from .wwvorbis import (W2V, transcode_setup, build_id_header, build_comment_header,
+                       ww_packet_to_vorbis)
+
+_LIB = None
+
+
+def library() -> CodebookLibrary:
+    global _LIB
+    if _LIB is None:
+        _LIB = CodebookLibrary()
+    return _LIB
+
+
+def packet_samples(blockflags, bs0, bs1):
+    """Samples produced by each packet (Vorbis overlap-add rule)."""
+    out = []
+    prev = None
+    for bf in blockflags:
+        cur = bs1 if bf else bs0
+        out.append(0 if prev is None else (prev // 4 + cur // 4))
+        prev = cur
+    return out
+
+
+def wem_to_ogg(wem: Wem):
+    """Returns (ogg_bytes, details dict)."""
+    lib = library()
+    v = wem.vorb
+    setup, info = transcode_setup(wem.setup_packet(), W2V, wem.channels, lib)
+    pkts, end = wem.audio_packets()
+    out_pkts = []
+    flags = []
+    prev_bf = 0
+    for i, (_, p) in enumerate(pkts):
+        nxt = pkts[i + 1][1][0] if i + 1 < len(pkts) else None
+        op, bf = ww_packet_to_vorbis(p, nxt, info, prev_bf, v["bs0_exp"] != v["bs1_exp"])
+        out_pkts.append(op)
+        flags.append(bf)
+        prev_bf = bf
+    bs0, bs1 = 1 << v["bs0_exp"], 1 << v["bs1_exp"]
+    samples = packet_samples(flags, bs0, bs1)
+    ow = OggWriter()
+    ow.page([build_id_header(wem.channels, wem.rate, v["bs0_exp"], v["bs1_exp"])], 0, bos=True)
+    ow.page([build_comment_header(), setup], 0)
+    g = 0
+    total = v["total_frames"]
+    for i, op in enumerate(out_pkts):
+        g += samples[i]
+        last = i == len(out_pkts) - 1
+        ow.page([op], min(g, total) if last else g, eos=last)
+    return ow.bytes(), dict(info=info, flags=flags, samples=samples, packets=pkts, data_end=end,
+                            sum_samples=sum(samples))