Update client ID generation to support MP3s with junk/padding bytes

CHANGELOG.md

@@ -12,6 +12,9 @@ This project adheres to [Semantic Versioning](https://semver.org).
 
 * Use try/except for track/disc number conversions.
 * Add check for files above maximum allowed upload size.
+* Properly calculate client ID for MP3s that don't
+  have an MPEG frame at the start of the file or
+	immediately following an ID3v2 tag.
 
 
 ## [2.5.0](https://github.com/thebigmunch/google-music-proto/releases/tag/2.5.0) (2019-07-22)

pyproject.toml

@@ -20,7 +20,7 @@ homepage = "https://github.com/thebigmunch/google-music-proto"
 python = "^3.6"
 
 attrs = ">=18.2,<19.4"
-audio-metadata = "^0.5"
+audio-metadata = "^0.6"
 marshmallow = "^2.0"
 pendulum = "^2.0"
 protobuf = "^3.5"

src/google_music_proto/musicmanager/utils.py

@@ -23,6 +23,31 @@ def generate_client_id(song):
 	md5sum = None
 	if isinstance(song, audio_metadata.FLAC):
 		md5sum = unhexlify(song.streaminfo.md5)
+	elif isinstance(song, audio_metadata.MP3):
+		m = md5()
+
+		if '_id3' in song and isinstance(song._id3, audio_metadata.ID3v2):
+			audio_start = song._id3._size
+		else:
+			audio_start = 0
+
+		audio_size = song.streaminfo._end - audio_start
+
+		with open(song.filepath, 'rb') as f:
+			f.seek(audio_start, os.SEEK_SET)
+
+			# Speed up by reading in chunks
+			read = 0
+			while True:
+				read_size = min(audio_size - read, 65536)
+				if read_size <= 0:
+					break
+
+				read += read_size
+				data = f.read(read_size)
+				m.update(data)
+
+		md5sum = m.digest()
 	else:
 		m = md5()
 
@@ -34,7 +59,7 @@ def generate_client_id(song):
 			read = 0
 			while True:
 				read_size = min(audio_size - read, 65536)
-				if not read_size:
+				if read_size <= 0:
 					break
 
 				read += read_size