Merge pull request #41 from google/libpython

Python library wrapper

9 files changed, 905 insertions, 170 deletions

diff --git a/README.md b/README.md
index d183393..9f4d8f0 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@ The directory layout is as follows :
 - include:      Library interface
 - src:          Source files
 - tools:        Standalone encoder/decoder tools
+- python:       Python wrapper
 - test:         Unit testing framework
 - fuzz:         Roundtrip fuzz testing harness
 - build:        Building outputs
@@ -62,7 +63,7 @@ Compiled library will be found in `bin` directory.
 
 ## Tools
 
-Tools can be all compiled, while involking `make` as follows :
+Tools can be all compiled, while invoking `make` as follows :
 
 ```sh
 $ make tools
@@ -138,6 +139,7 @@ The conformance reports can be found [here](conformance/README.md)
 The codec was [_here_](https://hydrogenaud.io/index.php/topic,122575.0.html)
 subjectively evaluated in a blind listening test.
 
+
 ## Meson build system
 
 Meson build system is also available to build and install lc3 codec in Linux
@@ -148,3 +150,18 @@ $ meson build
 $ cd build && meson install
 ```
 
+## Python wrapper
+
+A python wrapper, installed as follows, is available in the `python` directory.
+
+```sh
+$ python3 -m pip install ./python
+```
+
+Decoding and encoding tools are provided in `python/tools`, like C tools,
+you can easly test encoding / decoding loop with :
+
+```sh
+$ python3 ./python/tools/encoder.py <in.wav> --bitrate <bitrate> | \
+  python3 ./python/tools/decoder.py > <out.wav>
+```
diff --git a/python/LICENSE b/python/LICENSE
new file mode 100644
index 0000000..d645695
--- /dev/null
+++ b/python/LICENSE
@@ -0,0 +1,202 @@
+
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diff --git a/python/lc3.py b/python/lc3.py
new file mode 100644
index 0000000..4245b23
--- /dev/null
+++ b/python/lc3.py
@@ -0,0 +1,393 @@
+#
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import array
+import ctypes
+import enum
+
+from ctypes import c_bool, c_byte, c_int, c_uint, c_size_t, c_void_p
+from ctypes.util import find_library
+
+
+class _Base:
+
+    def __init__(self, frame_duration, samplerate, nchannels, **kwargs):
+
+        self.hrmode = False
+        self.dt_us = int(frame_duration * 1000)
+        self.sr_hz = int(samplerate)
+        self.sr_pcm_hz = self.sr_hz
+        self.nchannels = nchannels
+
+        libpath = None
+
+        for k in kwargs.keys():
+            if k == 'hrmode':
+                self.hrmode = bool(kwargs[k])
+            elif k == 'pcm_samplerate':
+                self.sr_pcm_hz = int(kwargs[k])
+            elif k == 'libpath':
+                libpath = kwargs[k]
+            else:
+                raise ValueError("Invalid keyword argument: " + k)
+
+        if self.dt_us not in [2500, 5000, 7500, 10000]:
+            raise ValueError(
+                "Invalid frame duration: %.1f ms" % frame_duration)
+
+        allowed_samplerate = [8000, 16000, 24000, 32000, 48000] \
+            if not self.hrmode else [48000, 96000]
+
+        if self.sr_hz not in allowed_samplerate:
+            raise ValueError("Invalid sample rate: %d Hz" % samplerate)
+
+        if libpath is None:
+            libpath = find_library("lc3")
+            if not libpath:
+                raise Exception("LC3 library not found")
+
+        lib = ctypes.cdll.LoadLibrary(libpath)
+
+        try:
+            lib.lc3_hr_frame_samples \
+                and lib.lc3_hr_frame_block_bytes \
+                and lib.lc3_hr_resolve_bitrate \
+                and lib.lc3_hr_delay_samples
+
+        except AttributeError:
+
+            if self.hrmode:
+                raise Exception('High-Resolution interface not available')
+
+            lib.lc3_hr_frame_samples = \
+                lambda hrmode, dt_us, sr_hz: \
+                lib.lc3_frame_samples(dt_us, sr_hz)
+
+            lib.lc3_hr_frame_block_bytes = \
+                lambda hrmode, dt_us, sr_hz, nchannels, bitrate: \
+                nchannels * lib.lc3_frame_bytes(dt_us, bitrate // 2)
+
+            lib.lc3_hr_resolve_bitrate = \
+                lambda hrmode, dt_us, sr_hz, nbytes: \
+                lib.lc3_resolve_bitrate(dt_us, nbytes)
+
+            lib.lc3_hr_delay_samples = \
+                lambda hrmode, dt_us, sr_hz: \
+                lib.lc3_delay_samples(dt_us, sr_hz)
+
+        lib.lc3_hr_frame_samples.argtypes = [c_bool, c_int, c_int]
+        lib.lc3_hr_frame_block_bytes.argtypes = \
+            [c_bool, c_int, c_int, c_int, c_int]
+        lib.lc3_hr_resolve_bitrate.argtypes = [c_bool, c_int, c_int, c_int]
+        lib.lc3_hr_delay_samples.argtypes = [c_bool, c_int, c_int]
+        self.lib = lib
+
+        libc = ctypes.cdll.LoadLibrary(find_library("c"))
+
+        self.malloc = libc.malloc
+        self.malloc.argtypes = [c_size_t]
+        self.malloc.restype = c_void_p
+
+        self.free = libc.free
+        self.free.argtypes = [c_void_p]
+
+    def get_frame_samples(self):
+        """
+        Returns the number of PCM samples in an LC3 frame
+        """
+        ret = self.lib.lc3_hr_frame_samples(
+            self.hrmode, self.dt_us, self.sr_pcm_hz)
+        if ret < 0:
+            raise ValueError("Bad parameters")
+        return ret
+
+    def get_frame_bytes(self, bitrate):
+        """
+        Returns the size of LC3 frame blocks, from bitrate in bit per seconds.
+        A target `bitrate` equals 0 or `INT32_MAX` returns respectively
+        the minimum and maximum allowed size.
+        """
+        ret = self.lib.lc3_hr_frame_block_bytes(
+            self.hrmode, self.dt_us, self.sr_hz, self.nchannels, bitrate)
+        if ret < 0:
+            raise ValueError("Bad parameters")
+        return ret
+
+    def resolve_bitrate(self, nbytes):
+        """
+        Returns the bitrate in bits per seconds, from the size of LC3 frames.
+        """
+        ret = self.lib.lc3_hr_resolve_bitrate(
+            self.hrmode, self.dt_us, self.sr_hz, nbytes)
+        if ret < 0:
+            raise ValueError("Bad parameters")
+        return ret
+
+    def get_delay_samples(self):
+        """
+         Returns the algorithmic delay, as a number of samples.
+         """
+        ret = self.lib.lc3_hr_delay_samples(
+            self.hrmode, self.dt_us, self.sr_pcm_hz)
+        if ret < 0:
+            raise ValueError("Bad parameters")
+        return ret
+
+    @staticmethod
+    def _resolve_pcm_format(bitdepth):
+        PCM_FORMAT_S16 = 0
+        PCM_FORMAT_S24 = 1
+        PCM_FORMAT_S24_3LE = 2
+        PCM_FORMAT_FLOAT = 3
+
+        match bitdepth:
+            case 16: return (PCM_FORMAT_S16, ctypes.c_int16)
+            case 24: return (PCM_FORMAT_S24_3LE, 3 * ctypes.c_byte)
+            case None: return (PCM_FORMAT_FLOAT, ctypes.c_float)
+            case _: raise ValueError("Could not interpret PCM bitdepth")
+
+
+class Encoder(_Base):
+    """
+    LC3 Encoder wrapper
+
+    The `frame_duration` expressed in milliseconds is any of 2.5, 5.0, 7.5
+    or 10.0. The `samplerate`, in Hertz, is any of 8000, 16000, 24000, 32000
+    or 48000, unless High-Resolution mode is enabled. In High-Resolution mode,
+    the `samplerate` is 48000 or 96000.
+
+    By default, one channel is processed. When `nchannels` is greater than one,
+    the PCM input stream is read interleaved and consecutives LC3 frames are
+    output, for each channel.
+
+    Keyword arguments:
+        hrmode    : Enable High-Resolution mode, default is `False`.
+        sr_pcm_hz : Input PCM samplerate, enable downsampling of input.
+        libpath   : LC3 library path and name
+    """
+
+    class c_encoder_t(c_void_p):
+        pass
+
+    def __init__(self, frame_duration, samplerate, nchannels=1, **kwargs):
+
+        super().__init__(frame_duration, samplerate, nchannels, **kwargs)
+
+        lib = self.lib
+
+        try:
+            lib.lc3_hr_encoder_size \
+                and lib.lc3_hr_setup_encoder
+
+        except AttributeError:
+
+            assert not self.hrmode
+
+            lib.lc3_hr_encoder_size = \
+                lambda hrmode, dt_us, sr_hz: \
+                lib.lc3_encoder_size(dt_us, sr_hz)
+
+            lib.lc3_hr_setup_encoder = \
+                lambda hrmode, dt_us, sr_hz, sr_pcm_hz, mem: \
+                lib.lc3_setup_encoder(dt_us, sr_hz, sr_pcm_hz, mem)
+
+        lib.lc3_hr_encoder_size.argtypes = [c_bool, c_int, c_int]
+        lib.lc3_hr_encoder_size.restype = c_uint
+
+        lib.lc3_hr_setup_encoder.argtypes = \
+            [c_bool, c_int, c_int, c_int, c_void_p]
+        lib.lc3_hr_setup_encoder.restype = self.c_encoder_t
+
+        lib.lc3_encode.argtypes = \
+            [self.c_encoder_t, c_int, c_void_p, c_int, c_int, c_void_p]
+
+        def new_encoder(): return lib.lc3_hr_setup_encoder(
+            self.hrmode, self.dt_us, self.sr_hz, self.sr_pcm_hz,
+            self.malloc(lib.lc3_hr_encoder_size(
+                self.hrmode, self.dt_us, self.sr_pcm_hz)))
+
+        self.__encoders = [new_encoder() for i in range(nchannels)]
+
+    def __del__(self):
+
+        try:
+            (self.free(encoder) for encoder in self.__encoders)
+        finally:
+            return
+
+    def encode(self, pcm, nbytes, bitdepth=None):
+        """
+        Encode LC3 frame(s), for each channel.
+
+        The `pcm` input is given in two ways. When no `bitdepth` is defined,
+        it's a vector of floating point values from -1 to 1, coding the sample
+        levels. When `bitdepth` is defined, `pcm` is interpreted as a byte-like
+        object, each sample coded on `bitdepth` bits (16 or 24).
+        The machine endianness, or little endian, is used for 16 or 24 bits
+        width, respectively.
+        In both cases, the `pcm` vector data is padded with zeros when
+        its length is less than the required input samples for the encoder.
+        Channels concatenation of encoded LC3 frames, of `nbytes`, is returned.
+        """
+
+        nchannels = self.nchannels
+        frame_samples = self.get_frame_samples()
+
+        (pcm_fmt, pcm_t) = self._resolve_pcm_format(bitdepth)
+        pcm_len = nchannels * frame_samples
+
+        if bitdepth is None:
+            pcm_buffer = array.array('f', pcm)
+
+            # Invert test to catch NaN
+            if not abs(sum(pcm)) / frame_samples < 2:
+                raise ValueError("Out of range PCM input")
+
+            padding = max(pcm_len - frame_samples, 0)
+            pcm_buffer.extend(array.array('f', [0] * padding))
+
+        else:
+            padding = max(pcm_len * ctypes.sizeof(pcm_t) - len(pcm), 0)
+            pcm_buffer = bytearray(pcm) + bytearray(padding)
+
+        data_buffer = (c_byte * nbytes)()
+        data_offset = 0
+
+        for (ich, encoder) in enumerate(self.__encoders):
+
+            pcm_offset = ich * ctypes.sizeof(pcm_t)
+            pcm = (pcm_t * (pcm_len - ich)).from_buffer(pcm_buffer, pcm_offset)
+
+            data_size = nbytes // nchannels + int(ich < nbytes % nchannels)
+            data = (c_byte * data_size).from_buffer(data_buffer, data_offset)
+            data_offset += data_size
+
+            ret = self.lib.lc3_encode(
+                encoder, pcm_fmt, pcm, nchannels, len(data), data)
+            if ret < 0:
+                raise ValueError("Bad parameters")
+
+        return bytes(data_buffer)
+
+
+class Decoder(_Base):
+    """
+    LC3 Decoder wrapper
+
+    The `frame_duration` expressed in milliseconds is any of 2.5, 5.0, 7.5
+    or 10.0. The `samplerate`, in Hertz, is any of 8000, 16000, 24000, 32000
+    or 48000, unless High-Resolution mode is enabled. In High-Resolution
+    mode, the `samplerate` is 48000 or 96000.
+
+    By default, one channel is processed. When `nchannels` is greater than one,
+    the PCM input stream is read interleaved and consecutives LC3 frames are
+    output, for each channel.
+
+    Keyword arguments:
+        hrmode    : Enable High-Resolution mode, default is `False`.
+        sr_pcm_hz : Output PCM samplerate, enable upsampling of output.
+        libpath   : LC3 library path and name
+    """
+
+    class c_decoder_t(c_void_p):
+        pass
+
+    def __init__(self, frame_duration, samplerate, nchannels=1, **kwargs):
+
+        super().__init__(frame_duration, samplerate, nchannels, **kwargs)
+
+        lib = self.lib
+
+        try:
+            lib.lc3_hr_decoder_size \
+                and lib.lc3_hr_setup_decoder
+
+        except AttributeError:
+
+            assert not self.hrmode
+
+            lib.lc3_hr_decoder_size = \
+                lambda hrmode, dt_us, sr_hz: \
+                lib.lc3_decoder_size(dt_us, sr_hz)
+
+            lib.lc3_hr_setup_decoder = \
+                lambda hrmode, dt_us, sr_hz, sr_pcm_hz, mem: \
+                lib.lc3_setup_decoder(dt_us, sr_hz, sr_pcm_hz, mem)
+
+        lib.lc3_hr_decoder_size.argtypes = [c_bool, c_int, c_int]
+        lib.lc3_hr_decoder_size.restype = c_uint
+
+        lib.lc3_hr_setup_decoder.argtypes = \
+            [c_bool, c_int, c_int, c_int, c_void_p]
+        lib.lc3_hr_setup_decoder.restype = self.c_decoder_t
+
+        lib.lc3_decode.argtypes = \
+            [self.c_decoder_t, c_void_p, c_int, c_int, c_void_p, c_int]
+
+        def new_decoder(): return lib.lc3_hr_setup_decoder(
+            self.hrmode, self.dt_us, self.sr_hz, self.sr_pcm_hz,
+            self.malloc(lib.lc3_hr_decoder_size(
+                self.hrmode, self.dt_us, self.sr_pcm_hz)))
+
+        self.__decoders = [new_decoder() for i in range(nchannels)]
+
+    def __del__(self):
+
+        try:
+            (self.free(decoder) for decoder in self.__decoders)
+        finally:
+            return
+
+    def decode(self, data, bitdepth=None):
+        """
+        Decode an LC3 frame
+
+        The input `data` is the channels concatenation of LC3 frames in a
+        byte-like object. Interleaved PCM samples are returned according to
+        the `bitdepth` indication.
+        When no `bitdepth` is defined, it's a vector of floating point values
+        from -1 to 1, coding the sample levels. When `bitdepth` is defined,
+        it returns a byte array, each sample coded on `bitdepth` bits.
+        The machine endianness, or little endian, is used for 16 or 24 bits
+        width, respectively.
+        """
+
+        nchannels = self.nchannels
+        frame_samples = self.get_frame_samples()
+
+        (pcm_fmt, pcm_t) = self._resolve_pcm_format(bitdepth)
+        pcm_len = nchannels * self.get_frame_samples()
+        pcm_buffer = (pcm_t * pcm_len)()
+
+        data_buffer = bytearray(data)
+        data_offset = 0
+
+        for (ich, decoder) in enumerate(self.__decoders):
+            pcm_offset = ich * ctypes.sizeof(pcm_t)
+            pcm = (pcm_t * (pcm_len - ich)).from_buffer(pcm_buffer, pcm_offset)
+
+            data_size = len(data_buffer) // nchannels + \
+                int(ich < len(data_buffer) % nchannels)
+            data = (c_byte * data_size).from_buffer(data_buffer, data_offset)
+            data_offset += data_size
+
+            ret = self.lib.lc3_decode(
+                decoder, data, len(data), pcm_fmt, pcm, self.nchannels)
+            if ret < 0:
+                raise ValueError("Bad parameters")
+
+        return array.array('f', pcm_buffer) \
+            if bitdepth is None else bytes(pcm_buffer)
diff --git a/python/pyproject.toml b/python/pyproject.toml
new file mode 100644
index 0000000..c1bb77c
--- /dev/null
+++ b/python/pyproject.toml
@@ -0,0 +1,16 @@
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[project]
+name = "lc3"
+version = "0.0.1"
+license = "Apache-2.0"
+authors = [
+  { name="Antoine Soulier", email="asoulier@google.com" },
+]
+description = "LC3 Codec library wrapper"
+requires-python = ">=3.10"
+
+[project.urls]
+Homepage = "https://github.com/google/liblc3"
diff --git a/python/tools/decoder.py b/python/tools/decoder.py
new file mode 100755
index 0000000..c10c1e4
--- /dev/null
+++ b/python/tools/decoder.py
@@ -0,0 +1,96 @@
+#!/usr/bin/env python3
+#
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import argparse
+import lc3
+import struct
+import sys
+import wave
+
+parser = argparse.ArgumentParser(description='LC3 Decoder')
+
+parser.add_argument(
+    'lc3_file', nargs='?',
+    help='Input bitstream file, default is stdin',
+    type=argparse.FileType('rb'), default=sys.stdin.buffer)
+
+parser.add_argument(
+    'wav_file', nargs='?',
+    help='Output wave file, default is stdout',
+    type=argparse.FileType('wb'), default=sys.stdout.buffer)
+
+parser.add_argument(
+    '--bitdepth',
+    help='Output bitdepth, default is 16 bits',
+    type=int, choices=[16, 24], default=16)
+
+parser.add_argument(
+    '--libpath', help='LC3 Library path')
+
+args = parser.parse_args()
+
+# --- LC3 File input ---
+
+f_lc3 = args.lc3_file
+
+header = struct.unpack('=HHHHHHHI', f_lc3.read(18))
+if header[0] != 0xcc1c:
+    raise ValueError('Invalid bitstream file')
+
+samplerate = header[2] * 100
+nchannels = header[4]
+frame_duration = header[5] / 100
+stream_length = header[7]
+
+# --- Setup output ---
+
+bitdepth = args.bitdepth
+pcm_size = nchannels * (bitdepth // 8)
+
+f_wav = args.wav_file
+wavfile = wave.open(f_wav)
+wavfile.setnchannels(nchannels)
+wavfile.setsampwidth(bitdepth // 8)
+wavfile.setframerate(samplerate)
+wavfile.setnframes(stream_length)
+
+# --- Setup decoder ---
+
+dec = lc3.Decoder(
+    frame_duration, samplerate, nchannels, libpath=args.libpath)
+frame_length = dec.get_frame_samples()
+encoded_length = stream_length + dec.get_delay_samples()
+
+# --- Decoding loop ---
+
+for i in range(0, encoded_length, frame_length):
+
+    lc3_frame_size = struct.unpack('=H', f_lc3.read(2))[0]
+    pcm = dec.decode(f_lc3.read(lc3_frame_size), bitdepth=bitdepth)
+
+    pcm = pcm[max(encoded_length - stream_length - i, 0) * pcm_size:
+              min(encoded_length - i, frame_length) * pcm_size]
+
+    wavfile.writeframesraw(pcm)
+
+# --- Cleanup ---
+
+wavfile.close()
+
+for f in (f_lc3, f_wav):
+    if f is not sys.stdout.buffer:
+        f.close()
diff --git a/python/tools/encoder.py b/python/tools/encoder.py
new file mode 100755
index 0000000..9f291ff
--- /dev/null
+++ b/python/tools/encoder.py
@@ -0,0 +1,88 @@
+#!/usr/bin/env python3
+#
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import argparse
+import lc3
+import struct
+import sys
+import wave
+
+parser = argparse.ArgumentParser(description='LC3 Encoder')
+
+parser.add_argument(
+    'wav_file', nargs='?',
+    help='Input wave file, default is stdin',
+    type=argparse.FileType('rb'), default=sys.stdin.buffer)
+
+parser.add_argument(
+    'lc3_file', nargs='?',
+    help='Output bitstream file, default is stdout',
+    type=argparse.FileType('wb'), default=sys.stdout.buffer)
+
+parser.add_argument(
+    '--bitrate', help='Bitrate in bps', type=int, required=True)
+
+parser.add_argument(
+    '--frame_duration', help='Frame duration in ms', type=float, default=10)
+
+parser.add_argument(
+    '--libpath', help='LC3 Library path')
+
+args = parser.parse_args()
+
+# --- WAV File input ---
+
+f_wav = args.wav_file
+wavfile = wave.open(f_wav, 'rb')
+
+samplerate = wavfile.getframerate()
+nchannels = wavfile.getnchannels()
+bitdepth = wavfile.getsampwidth() * 8
+stream_length = wavfile.getnframes()
+
+# --- Setup encoder ---
+
+enc = lc3.Encoder(
+    args.frame_duration, samplerate, nchannels, libpath=args.libpath)
+frame_size = enc.get_frame_bytes(args.bitrate)
+frame_length = enc.get_frame_samples()
+bitrate = enc.resolve_bitrate(frame_size)
+
+# --- Setup output ---
+
+f_lc3 = args.lc3_file
+f_lc3.write(struct.pack(
+    '=HHHHHHHI', 0xcc1c, 18,
+    samplerate // 100, bitrate // 100, nchannels,
+    int(args.frame_duration * 100), 0, stream_length))
+
+# --- Encoding loop ---
+
+for i in range(0, stream_length, frame_length):
+
+    f_lc3.write(struct.pack('=H', frame_size))
+
+    pcm = wavfile.readframes(frame_length)
+    f_lc3.write(enc.encode(pcm, frame_size, bitdepth=bitdepth))
+
+# --- Cleanup ---
+
+wavfile.close()
+
+for f in (f_wav, f_lc3):
+    if f is not sys.stdout.buffer:
+        f.close()
diff --git a/python/tools/specgram.py b/python/tools/specgram.py
new file mode 100755
index 0000000..42781d4
--- /dev/null
+++ b/python/tools/specgram.py
@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+#
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import argparse
+import lc3
+import matplotlib
+import matplotlib.pyplot as plt
+import numpy as np
+import scipy.signal as signal
+
+matplotlib.use('QtAgg')
+
+parser = argparse.ArgumentParser(description='LC3 Encoder')
+
+parser.add_argument(
+    '--frame_duration', help='Frame duration (ms)', type=float, default=10)
+
+parser.add_argument(
+    '--sample_rate', help='Sampling frequency (Hz)', type=float, default=48000)
+
+parser.add_argument(
+    '--hrmode', help='Enable high-resolution mode', action='store_true')
+
+parser.add_argument(
+    '--bitrate', help='Bitrate (bps)', type=int, default=96000)
+
+parser.add_argument(
+    '--libpath', help='LC3 Library path')
+
+args = parser.parse_args()
+
+# --- Setup encoder + decoder ---
+
+fs = args.sample_rate
+
+enc = lc3.Encoder(
+    args.frame_duration, fs, hrmode=args.hrmode, libpath=args.libpath)
+dec = lc3.Decoder(
+    args.frame_duration, fs, hrmode=args.hrmode, libpath=args.libpath)
+
+frame_len = enc.get_frame_samples()
+delay_len = enc.get_delay_samples()
+
+# --- Generate 10 seconds chirp ---
+
+n = 10 * int(fs)
+t = np.arange(n - (n % frame_len)) / fs
+s = signal.chirp(t, f0=10, f1=fs/2, t1=t[-1], phi=-90, method='linear')
+
+# --- Encoding / decoding loop ---
+
+frame_size = enc.get_frame_bytes(args.bitrate)
+bitrate = enc.resolve_bitrate(frame_size)
+
+y = np.empty(len(s) + frame_len)
+
+for i in range(0, len(s), frame_len):
+    y[i:i+frame_len] = dec.decode(enc.encode(s[i:i+frame_len], frame_size))
+
+y[len(s):] = dec.decode(enc.encode(np.zeros(frame_len), frame_size))
+y = y[delay_len:len(s)+delay_len]
+
+# --- Plot spectrograms ---
+
+fig, (ax1, ax2) = plt.subplots(nrows=2, sharex=True)
+
+NFFT = 512
+for (ax, s) in [(ax1, s), (ax2, y)]:
+    ax.specgram(s, Fs=fs, NFFT=NFFT, pad_to=4*NFFT, noverlap=NFFT//2,
+                vmin=-160, vmax=0)
+
+ax1.set_title('Input signal')
+ax1.set_ylabel('Frequency (Hz)')
+
+ax2.set_title(('Processed signal (%.1f kbps)' % (bitrate/1000)))
+ax2.set_ylabel('Frequency (Hz)')
+
+plt.show()
diff --git a/test/decoder.py b/test/decoder.py
index 26cdccc..388fc62 100755..100644
--- a/test/decoder.py
+++ b/test/decoder.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python3
 #
 # Copyright 2022 Google LLC
 #
@@ -27,8 +26,6 @@ import tables as T, appendix_c as C
 import mdct, energy, bwdet, sns, tns, spec, ltpf
 import bitstream
 
-### ------------------------------------------------------------------------ ###
-
 class Decoder:
 
     def __init__(self, dt_ms, sr_hz):
@@ -96,8 +93,6 @@ class Decoder:
 
         return x
 
-### ------------------------------------------------------------------------ ###
-
 def check_appendix_c(dt):
 
     i0 = dt - T.DT_7M5
@@ -120,79 +115,3 @@ def check():
         ok = ok and check_appendix_c(dt)
 
     return ok
-
-### ------------------------------------------------------------------------ ###
-
-if __name__ == "__main__":
-
-    parser = argparse.ArgumentParser(description='LC3 Decoder Test Framework')
-    parser.add_argument('lc3_file',
-        help='Input bitstream file', type=argparse.FileType('r'))
-    parser.add_argument('--pyout',
-        help='Python output file', type=argparse.FileType('w'))
-    parser.add_argument('--cout',
-        help='C output file', type=argparse.FileType('w'))
-    args = parser.parse_args()
-
-    ### File Header ###
-
-    f_lc3 = open(args.lc3_file.name, 'rb')
-
-    header = struct.unpack('=HHHHHHHI', f_lc3.read(18))
-
-    if header[0] != 0xcc1c:
-        raise ValueError('Invalid bitstream file')
-
-    if header[4] != 1:
-        raise ValueError('Unsupported number of channels')
-
-    sr_hz = header[2] * 100
-    bitrate = header[3] * 100
-    nchannels = header[4]
-    dt_ms = header[5] / 100
-
-    f_lc3.seek(header[1])
-
-    ### Setup ###
-
-    dec = Decoder(dt_ms, sr_hz)
-    dec_c = lc3.setup_decoder(int(dt_ms * 1000), sr_hz)
-
-    pcm_c  = np.empty(0).astype(np.int16)
-    pcm_py = np.empty(0).astype(np.int16)
-
-    ### Decoding loop ###
-
-    nframes = 0
-
-    while True:
-
-        data = f_lc3.read(2)
-        if len(data) != 2:
-            break
-
-        (frame_nbytes,) = struct.unpack('=H', data)
-
-        print('Decoding frame %d' % nframes, end='\r')
-
-        data = f_lc3.read(frame_nbytes)
-
-        x = dec.run(data)
-        pcm_py = np.append(pcm_py,
-            np.clip(np.round(x), -32768, 32767).astype(np.int16))
-
-        x_c = lc3.decode(dec_c, data)
-        pcm_c = np.append(pcm_c, x_c)
-
-        nframes += 1
-
-    print('done ! %16s' % '')
-
-    ### Terminate ###
-
-    if args.pyout:
-        wavfile.write(args.pyout.name, sr_hz, pcm_py)
-    if args.cout:
-        wavfile.write(args.cout.name, sr_hz, pcm_c)
-
-### ------------------------------------------------------------------------ ###
diff --git a/test/encoder.py b/test/encoder.py
index f687d4b..913420e 100755..100644
--- a/test/encoder.py
+++ b/test/encoder.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python3
 #
 # Copyright 2022 Google LLC
 #
@@ -28,8 +27,6 @@ import attdet, ltpf
 import mdct, energy, bwdet, sns, tns, spec
 import bitstream
 
-### ------------------------------------------------------------------------ ###
-
 class Encoder:
 
     def __init__(self, dt_ms, sr_hz):
@@ -104,8 +101,6 @@ class Encoder:
 
         return data
 
-### ------------------------------------------------------------------------ ###
-
 def check_appendix_c(dt):
 
     i0 = dt - T.DT_7M5
@@ -128,86 +123,3 @@ def check():
         ok = ok and check_appendix_c(dt)
 
     return ok
-
-### ------------------------------------------------------------------------ ###
-
-def dump(data):
-    for i in range(0, len(data), 20):
-        print(''.join('{:02x} '.format(x)
-            for x in data[i:min(i+20, len(data))] ))
-
-if __name__ == "__main__":
-
-    parser = argparse.ArgumentParser(description='LC3 Encoder Test Framework')
-    parser.add_argument('wav_file',
-        help='Input wave file', type=argparse.FileType('r'))
-    parser.add_argument('--bitrate',
-        help='Bitrate in bps', type=int, required=True)
-    parser.add_argument('--dt',
-        help='Frame duration in ms', type=float, default=10)
-    parser.add_argument('--pyout',
-        help='Python output file', type=argparse.FileType('w'))
-    parser.add_argument('--cout',
-        help='C output file', type=argparse.FileType('w'))
-    args = parser.parse_args()
-
-    if args.bitrate < 16000 or args.bitrate > 320000:
-        raise ValueError('Invalid bitate %d bps' % args.bitrate)
-
-    if args.dt not in (7.5, 10):
-        raise ValueError('Invalid frame duration %.1f ms' % args.dt)
-
-    (sr_hz, pcm) = wavfile.read(args.wav_file.name)
-    if sr_hz not in (8000, 16000, 24000, 320000, 48000):
-        raise ValueError('Unsupported input samplerate: %d' % sr_hz)
-    if pcm.ndim != 1:
-        raise ValueError('Only single channel wav file supported')
-
-    ### Setup ###
-
-    enc = Encoder(args.dt, sr_hz)
-    enc_c = lc3.setup_encoder(int(args.dt * 1000), sr_hz)
-
-    frame_samples = int((args.dt * sr_hz) / 1000)
-    frame_nbytes = int((args.bitrate * args.dt) / (1000 * 8))
-
-    ### File Header ###
-
-    f_py = open(args.pyout.name, 'wb') if args.pyout else None
-    f_c  = open(args.cout.name , 'wb') if args.cout  else None
-
-    header = struct.pack('=HHHHHHHI', 0xcc1c, 18,
-        sr_hz // 100, args.bitrate // 100, 1, int(args.dt * 100), 0, len(pcm))
-
-    for f in (f_py, f_c):
-        if f: f.write(header)
-
-    ### Encoding loop ###
-
-    if len(pcm) % frame_samples > 0:
-        pcm = np.append(pcm, np.zeros(frame_samples - (len(pcm) % frame_samples)))
-
-    for i in range(0, len(pcm), frame_samples):
-
-        print('Encoding frame %d' % (i // frame_samples), end='\r')
-
-        frame_pcm = pcm[i:i+frame_samples]
-
-        data = enc.run(frame_pcm, frame_nbytes)
-        data_c = lc3.encode(enc_c, frame_pcm, frame_nbytes)
-
-        for f in (f_py, f_c):
-            if f: f.write(struct.pack('=H', frame_nbytes))
-
-        if f_py: f_py.write(data)
-        if f_c: f_c.write(data_c)
-
-    print('done ! %16s' % '')
-
-    ### Terminate ###
-
-    for f in (f_py, f_c):
-        if f: f.close()
-
-
-### ------------------------------------------------------------------------ ###