ADM impl

wavinfo/wave_adm_reader.py

@@ -0,0 +1,55 @@
+"""
+ADM Reader
+"""
+
+from struct import unpack, unpack_from, calcsize
+from dataclasses import dataclass
+from io import BytesIO
+
+from lxml import etree as ET
+
+@dataclass
+class ChannelEntry:
+    """
+    A `chna` chunk table entry.
+    """
+
+    track_index: int
+    "Track index (indexed from 1)"
+
+    uid: str
+    "audioTrackUID"
+
+    track_ref: str
+    "audioTrackFormatID"
+
+    pack_ref: str
+    "audioPackFormatID"
+
+
+class WavADMReader:
+    """
+    Reads XML data from an EBU ADM (Audio Definiton Model) WAV File.
+    """
+
+    def __init__(self, axml_data: bytes, chna_data: bytes) -> None:
+        header_fmt = "<HH"
+        uid_fmt = "<H12s14s11sx"
+
+        self.axml = ET.parse(BytesIO(axml_data))
+
+        self.track_count, uid_count = unpack(header_fmt, chna_data)
+
+        self.channel_uids = []
+
+        offset = calcsize(header_fmt)
+        for _ in range(uid_count):
+
+            track_index, uid, track_ref, pack_ref = unpack_from(uid_fmt, chna_data, offset)
+
+            # these values are either ascii or all null
+
+            self.channel_uids.append(ChannelEntry(track_index,
+                uid.decode('ascii') , track_ref.decode('ascii'), pack_ref.decode('ascii')))
+
+            offset += calcsize(uid_fmt)