diff --git a/README.md b/README.md
index b9269f9..90c99f2 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,7 @@ it is not supported, please submit an issue!
   and Dolby Atmos `dbmd` metadata for re-renders and mixdowns.
 * Wave embedded [cue markers][cues], cue marker labels, notes and timed ranges as used
   by Zoom, iZotope RX, etc.
+* Wave embedded [sampler][smpl] and sample loop metadata.
 * The [wav format][format] is also parsed, so you can access the basic sample rate 
   and channel count information.
 
@@ -38,6 +39,7 @@ it is not supported, please submit an issue!
 [format]:https://wavinfo.readthedocs.io/en/latest/classes.html#wavinfo.wave_reader.WavAudioFormat
 [cues]:https://wavinfo.readthedocs.io/en/latest/scopes/cue.html
 [bext]:https://wavinfo.readthedocs.io/en/latest/scopes/bext.html
+[smpl]:https://wavinfo.readthedocs.io/en/latest/scopes/smpl.html
 [smpte_330m2011]:https://wavinfo.readthedocs.io/en/latest/scopes/bext.html#wavinfo.wave_bext_reader.WavBextReader.umid
 [adm]:https://wavinfo.readthedocs.io/en/latest/scopes/adm.html
 [ebu3285s6]:https://wavinfo.readthedocs.io/en/latest/scopes/dolby.html
diff --git a/docs/source/scopes/smpl.rst b/docs/source/scopes/smpl.rst
new file mode 100644
index 0000000..bd533c7
--- /dev/null
+++ b/docs/source/scopes/smpl.rst
@@ -0,0 +1,14 @@
+
+Sampler Metadata
+=================
+
+Class Reference
+---------------
+
+.. automodule:: wavinfo.wave_smpl_reader
+
+.. autoclass:: wavinfo.wave_smpl_reader.WavSmplReader
+    :members:
+
+.. autoclass:: wavinfo.wave_smpl_reader.WaveSmplLoop
+    :members:
diff --git a/pyproject.toml b/pyproject.toml
index 19e7eda..511e7ac 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -6,7 +6,7 @@ build-backend = "poetry.core.masonry.api"
 
 [tool.poetry]
 name = "wavinfo"
-version = "3.0.1"
+version = "3.1.0"
 description = "Probe WAVE files for all metadata"
 authors = ["Jamie Hardt <jamiehardt@me.com>"]
 license = "MIT" 
diff --git a/tests/test_files/smpl/alarm_citizen_loop1_udata.wav b/tests/test_files/smpl/alarm_citizen_loop1_udata.wav
new file mode 100644
index 0000000..08b0210
Binary files /dev/null and b/tests/test_files/smpl/alarm_citizen_loop1_udata.wav differ
diff --git a/wavinfo/__main__.py b/wavinfo/__main__.py
index 5d444b7..6f9b560 100644
--- a/wavinfo/__main__.py
+++ b/wavinfo/__main__.py
@@ -15,7 +15,7 @@ def default(self, o):
         if isinstance(o, Enum):
             return o._name_
         elif isinstance(o, bytes):
-            return b64encode(o).decode('ascii')
+            return 'base64:' + b64encode(o).decode('ascii')
         else:
             return super().default(o)
 
diff --git a/wavinfo/wave_smpl_reader.py b/wavinfo/wave_smpl_reader.py
index 746689d..2dcecf6 100644
--- a/wavinfo/wave_smpl_reader.py
+++ b/wavinfo/wave_smpl_reader.py
@@ -8,7 +8,7 @@ class WaveSmplLoop(NamedTuple):
     loop_type: int
     start: int
     end: int
-    fraction: int
+    detune_cents: int
     repetition_count: int
 
     def loop_type_desc(self):
@@ -30,7 +30,7 @@ def to_dict(self):
             'loop_type_description': self.loop_type_desc(),
             'start_samples': self.start,
             'end_samples': self.end,
-            'fraction': self.fraction,
+            'detune_cents': self.detune_cents,
             'repetition_count': self.repetition_count,
         }
 
@@ -42,8 +42,8 @@ def __init__(self, smpl_data: bytes):
         Read sampler metadata from smpl chunk.
         """
 
-        header_field_fmt = "<IIIIIIbbbbII"
-        loop_field_fmt = "<IIIIII"
+        header_field_fmt = "<IIIIiIbbbbII"
+        loop_field_fmt = "<IIIIiI"
         header_size = struct.calcsize(header_field_fmt)
         loop_size = struct.calcsize(loop_field_fmt)
 
@@ -65,7 +65,7 @@ def __init__(self, smpl_data: bytes):
         self.midi_note: int = unpacked_data[3]
 
         #: The number of semitones above the MIDI note the loops tune for.
-        self.midi_pitch_fraction_semis: int = unpacked_data[4]
+        self.midi_pitch_detune_cents: int = unpacked_data[4]
 
         #: SMPTE timecode format, one of (0, 24, 25, 29, 30)
         self.smpte_format: int = unpacked_data[5]
@@ -89,13 +89,16 @@ def __init__(self, smpl_data: bytes):
                 loop_type=unpacked_loop[1],
                 start=unpacked_loop[2],
                 end=unpacked_loop[3],
-                fraction=unpacked_loop[4],
+                detune_cents=unpacked_loop[4],
                 repetition_count=unpacked_loop[5]))
 
         #: Sampler-specific user data.
-        self.sampler_udata: bytes = smpl_data[
-            header_size + loop_size * loop_count:
-            header_size + loop_size * loop_count + sampler_udata_length]
+        self.sampler_udata: bytes | None = None
+
+        if sampler_udata_length > 0:
+            self.sampler_udata = smpl_data[
+                header_size + loop_size * loop_count:
+                header_size + loop_size * loop_count + sampler_udata_length]
 
     def to_dict(self):
         return {
@@ -103,7 +106,7 @@ def to_dict(self):
             'product': self.product,
             'sample_period_ns': self.sample_period_ns,
             'midi_note': self.midi_note,
-            'midi_pitch_fraction_semis': self.midi_pitch_fraction_semis,
+            'midi_pitch_detune_cents': self.midi_pitch_detune_cents,
             'smpte_format': self.smpte_format,
             'smpte_offset': "%02i:%02i:%02i:%02i" % self.smpte_offset,
             'loops': [x.to_dict() for x in self.sample_loops],