Fixes and testing with files

wavinfo/wave_reader.py

@@ -0,0 +1,100 @@
+import struct
+
+class WavInfoReader():
+    """
+    format : WAV format
+    bext   : The Broadcast-WAV extension as definied by EBU Tech 3285 v2 (2011)
+
+    """
+
+    def __init__(self, path):
+        with open(path, 'rb') as f:
+            chunks = parse_chunk(f)
+            
+            main_list = chunks.children
+            f.seek(0)
+            
+            self.fmt    = self._get_format(main_list,f)
+            self.info   = self._get_bext(main_list,f)
+            self.ixml   = self._get_ixml(main_list,f)
+
+
+    def _get_format(self,chunks,f):
+        fmt_chunk = next(chunk for chunk in chunks if chunk.ident == b'fmt ')
+        fmt_data = fmt_chunk.read_data(f)
+        
+        # The format chunk is
+        # audio_format    U16
+        # channel_count   U16
+        # sample_rate     U32   Note an integer
+        # byte_rate       U32   == SampleRate * NumChannels * BitsPerSample/8
+        # block_align     U16   == NumChannels * BitsPerSample/8
+        # bits_per_sampl  U16
+        unpacked = struct.unpack("<HHIIHH", fmt_data)
+
+        return WavInfoFormat(audio_format = unpacked[0],
+                channel_count = unpacked[1],
+                sample_rate   = unpacked[2],
+                byte_rate     = unpacked[3],
+                block_align   = unpacked[4],
+                bits_per_sample = unpacked[5]
+                )
+
+    def _get_bext(self,chunks,f):
+
+        bext_chunk = next((chunk for chunk in chunks if chunk.ident == b'bext'),None)
+        bext_data = bext_chunk.read_data(from_stream=f)
+
+        # description[256]      
+        # originator[32]
+        # originatorref[32]
+        # originatordate[10]   "YYYY:MM:DD"
+        # originatortime[8]    "HH:MM:SS"
+        # lowtimeref U32
+        # hightimeref U32
+        # version U16
+        # umid[64]
+        # 
+        # EBU 3285 fields
+        # loudnessvalue S16    (in LUFS*100)
+        # loudnessrange S16    (in LUFS*100)
+        # maxtruepeak   S16    (in dbTB*100)
+        # maxmomentaryloudness S16 (LUFS*100)
+        # maxshorttermloudness S16 (LUFS*100)
+        # reserved[180]
+        # codinghistory []
+        print(len(bext_data))
+        packstring = "<256s"+ "32s" + "32s" + "10s" + "8s" + "QH" + "64s" + "hhhhh" + "180s"
+        
+        rest_starts = struct.calcsize(packstring)
+        unpacked = struct.unpack(packstring, bext_data[:rest_starts])
+        
+
+        return WavBextFormat(description=unpacked[0].decode('ascii').rstrip(' \t\r\n\0'),
+                originator      = unpacked[1].decode('ascii').rstrip(' \t\r\n\0'),
+                originator_ref  = unpacked[2].decode('ascii').rstrip(' \t\r\n\0'),
+                originator_date = unpacked[3].decode('ascii').rstrip(' \t\r\n\0'),
+                originator_time = unpacked[4].decode('ascii').rstrip(' \t\r\n\0'),
+                time_reference  = unpacked[5],
+                version         = unpacked[6],
+                umid            = unpacked[7],
+                loudness_value  = unpacked[8],
+                loudness_range  = unpacked[9],
+                max_true_peak   = unpacked[10],
+                max_momentary_loudness = unpacked[11],
+                max_shortterm_loudness = unpacked[12],
+                coding_history = bext_data[rest_starts:].decode('ascii').rstrip(' \t\r\n\0')
+                )
+
+    def _get_ixml(self,chunks,f):
+
+        ixml_chunk = next((chunk for chunk in chunks if chunk.ident == b'iXML'),None)
+        ixml_data = ixml_chunk.read_data(from_stream=f)
+        ixml_string = ixml_data.decode('utf-8')
+
+        return WavIXMLFormat(ixml_string)
+        
+
+
+        
+