Add Volume Control Service

8 files changed, 661 insertions, 4 deletions

diff --git a/.vscode/settings.json b/.vscode/settings.json
index 93e9ece..98b1d02 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -72,6 +72,8 @@
         "substates",
         "tobytes",
         "tsep",
+        "UNMUTE",
+        "unmuted",
         "usbmodem",
         "vhci",
         "websockets",
diff --git a/bumble/profiles/vcp.py b/bumble/profiles/vcp.py
new file mode 100644
index 0000000..0788219
--- /dev/null
+++ b/bumble/profiles/vcp.py
@@ -0,0 +1,228 @@
+# Copyright 2021-2024 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
+#
+#      https://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.
+
+
+# -----------------------------------------------------------------------------
+# Imports
+# -----------------------------------------------------------------------------
+from __future__ import annotations
+import enum
+
+from bumble import att
+from bumble import device
+from bumble import gatt
+from bumble import gatt_client
+
+from typing import Optional
+
+# -----------------------------------------------------------------------------
+# Constants
+# -----------------------------------------------------------------------------
+
+MIN_VOLUME = 0
+MAX_VOLUME = 255
+
+
+class ErrorCode(enum.IntEnum):
+    '''
+    See Volume Control Service 1.6. Application error codes.
+    '''
+
+    INVALID_CHANGE_COUNTER = 0x80
+    OPCODE_NOT_SUPPORTED = 0x81
+
+
+class VolumeFlags(enum.IntFlag):
+    '''
+    See Volume Control Service 3.3. Volume Flags.
+    '''
+
+    VOLUME_SETTING_PERSISTED = 0x01
+    # RFU
+
+
+class VolumeControlPointOpcode(enum.IntEnum):
+    '''
+    See Volume Control Service Table 3.3: Volume Control Point procedure requirements.
+    '''
+
+    # fmt: off
+    RELATIVE_VOLUME_DOWN        = 0x00
+    RELATIVE_VOLUME_UP          = 0x01
+    UNMUTE_RELATIVE_VOLUME_DOWN = 0x02
+    UNMUTE_RELATIVE_VOLUME_UP   = 0x03
+    SET_ABSOLUTE_VOLUME         = 0x04
+    UNMUTE                      = 0x05
+    MUTE                        = 0x06
+
+
+# -----------------------------------------------------------------------------
+# Server
+# -----------------------------------------------------------------------------
+class VolumeControlService(gatt.TemplateService):
+    UUID = gatt.GATT_VOLUME_CONTROL_SERVICE
+
+    volume_state: gatt.Characteristic
+    volume_control_point: gatt.Characteristic
+    volume_flags: gatt.Characteristic
+
+    volume_setting: int
+    muted: int
+    change_counter: int
+
+    def __init__(
+        self,
+        step_size: int = 16,
+        volume_setting: int = 0,
+        muted: int = 0,
+        change_counter: int = 0,
+        volume_flags: int = 0,
+    ) -> None:
+        self.step_size = step_size
+        self.volume_setting = volume_setting
+        self.muted = muted
+        self.change_counter = change_counter
+
+        self.volume_state = gatt.Characteristic(
+            uuid=gatt.GATT_VOLUME_STATE_CHARACTERISTIC,
+            properties=(
+                gatt.Characteristic.Properties.READ
+                | gatt.Characteristic.Properties.NOTIFY
+            ),
+            permissions=gatt.Characteristic.Permissions.READ_REQUIRES_ENCRYPTION,
+            value=gatt.CharacteristicValue(read=self._on_read_volume_state),
+        )
+        self.volume_control_point = gatt.Characteristic(
+            uuid=gatt.GATT_VOLUME_CONTROL_POINT_CHARACTERISTIC,
+            properties=gatt.Characteristic.Properties.WRITE,
+            permissions=gatt.Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION,
+            value=gatt.CharacteristicValue(write=self._on_write_volume_control_point),
+        )
+        self.volume_flags = gatt.Characteristic(
+            uuid=gatt.GATT_VOLUME_FLAGS_CHARACTERISTIC,
+            properties=gatt.Characteristic.Properties.READ,
+            permissions=gatt.Characteristic.Permissions.READ_REQUIRES_ENCRYPTION,
+            value=bytes([volume_flags]),
+        )
+
+        super().__init__(
+            [
+                self.volume_state,
+                self.volume_control_point,
+                self.volume_flags,
+            ]
+        )
+
+    @property
+    def volume_state_bytes(self) -> bytes:
+        return bytes([self.volume_setting, self.muted, self.change_counter])
+
+    @volume_state_bytes.setter
+    def volume_state_bytes(self, new_value: bytes) -> None:
+        self.volume_setting, self.muted, self.change_counter = new_value
+
+    def _on_read_volume_state(self, _connection: Optional[device.Connection]) -> bytes:
+        return self.volume_state_bytes
+
+    def _on_write_volume_control_point(
+        self, connection: Optional[device.Connection], value: bytes
+    ) -> None:
+        assert connection
+
+        opcode = VolumeControlPointOpcode(value[0])
+        change_counter = value[1]
+
+        if change_counter != self.change_counter:
+            raise att.ATT_Error(ErrorCode.INVALID_CHANGE_COUNTER)
+
+        handler = getattr(self, '_on_' + opcode.name.lower())
+        if handler(*value[2:]):
+            self.change_counter = (self.change_counter + 1) % 256
+            connection.abort_on(
+                'disconnection',
+                connection.device.notify_subscribers(
+                    attribute=self.volume_state,
+                    value=self.volume_state_bytes,
+                ),
+            )
+            self.emit(
+                'volume_state', self.volume_setting, self.muted, self.change_counter
+            )
+
+    def _on_relative_volume_down(self) -> bool:
+        old_volume = self.volume_setting
+        self.volume_setting = max(self.volume_setting - self.step_size, MIN_VOLUME)
+        return self.volume_setting != old_volume
+
+    def _on_relative_volume_up(self) -> bool:
+        old_volume = self.volume_setting
+        self.volume_setting = min(self.volume_setting + self.step_size, MAX_VOLUME)
+        return self.volume_setting != old_volume
+
+    def _on_unmute_relative_volume_down(self) -> bool:
+        old_volume, old_muted_state = self.volume_setting, self.muted
+        self.volume_setting = max(self.volume_setting - self.step_size, MIN_VOLUME)
+        self.muted = 0
+        return (self.volume_setting, self.muted) != (old_volume, old_muted_state)
+
+    def _on_unmute_relative_volume_up(self) -> bool:
+        old_volume, old_muted_state = self.volume_setting, self.muted
+        self.volume_setting = min(self.volume_setting + self.step_size, MAX_VOLUME)
+        self.muted = 0
+        return (self.volume_setting, self.muted) != (old_volume, old_muted_state)
+
+    def _on_set_absolute_volume(self, volume_setting: int) -> bool:
+        old_volume_setting = self.volume_setting
+        self.volume_setting = volume_setting
+        return old_volume_setting != self.volume_setting
+
+    def _on_unmute(self) -> bool:
+        old_muted_state = self.muted
+        self.muted = 0
+        return self.muted != old_muted_state
+
+    def _on_mute(self) -> bool:
+        old_muted_state = self.muted
+        self.muted = 1
+        return self.muted != old_muted_state
+
+
+# -----------------------------------------------------------------------------
+# Client
+# -----------------------------------------------------------------------------
+class VolumeControlServiceProxy(gatt_client.ProfileServiceProxy):
+    SERVICE_CLASS = VolumeControlService
+
+    volume_control_point: gatt_client.CharacteristicProxy
+
+    def __init__(self, service_proxy: gatt_client.ServiceProxy) -> None:
+        self.service_proxy = service_proxy
+
+        self.volume_state = gatt.PackedCharacteristicAdapter(
+            service_proxy.get_characteristics_by_uuid(
+                gatt.GATT_VOLUME_STATE_CHARACTERISTIC
+            )[0],
+            'BBB',
+        )
+
+        self.volume_control_point = service_proxy.get_characteristics_by_uuid(
+            gatt.GATT_VOLUME_CONTROL_POINT_CHARACTERISTIC
+        )[0]
+
+        self.volume_flags = gatt.PackedCharacteristicAdapter(
+            service_proxy.get_characteristics_by_uuid(
+                gatt.GATT_VOLUME_FLAGS_CHARACTERISTIC
+            )[0],
+            'B',
+        )
diff --git a/examples/leaudio.json b/examples/leaudio.json
index c4c5a11..ad5f6c8 100644
--- a/examples/leaudio.json
+++ b/examples/leaudio.json
@@ -2,5 +2,6 @@
     "name": "Bumble-LEA",
     "keystore": "JsonKeyStore",
     "address": "F0:F1:F2:F3:F4:FA",
+    "class_of_device": 2376708,
     "advertising_interval": 100
 }
diff --git a/examples/leaudio_with_classic.json b/examples/leaudio_with_classic.json
new file mode 100644
index 0000000..8b0d593
--- /dev/null
+++ b/examples/leaudio_with_classic.json
@@ -0,0 +1,9 @@
+{
+    "name": "Bumble-LEA",
+    "keystore": "JsonKeyStore",
+    "address": "F0:F1:F2:F3:F4:FA",
+    "classic_enabled": true,
+    "cis_enabled": true,
+    "class_of_device": 2376708,
+    "advertising_interval": 100
+}
diff --git a/examples/run_unicast_server.py b/examples/run_unicast_server.py
index 35e124d..7a63f51 100644
--- a/examples/run_unicast_server.py
+++ b/examples/run_unicast_server.py
@@ -99,14 +99,14 @@ async def main() -> None:
                         coding_format=CodingFormat(CodecID.LC3),
                         codec_specific_capabilities=CodecSpecificCapabilities(
                             supported_sampling_frequencies=(
-                                SupportedSamplingFrequency.FREQ_24000
+                                SupportedSamplingFrequency.FREQ_48000
                             ),
                             supported_frame_durations=(
                                 SupportedFrameDuration.DURATION_10000_US_SUPPORTED
                             ),
                             supported_audio_channel_counts=[1],
-                            min_octets_per_codec_frame=60,
-                            max_octets_per_codec_frame=60,
+                            min_octets_per_codec_frame=120,
+                            max_octets_per_codec_frame=120,
                             supported_max_codec_frames_per_sdu=1,
                         ),
                     ),
@@ -159,7 +159,7 @@ async def main() -> None:
             + struct.pack(
                 '<HHHHHHI',
                 18,  # Header length.
-                24000 // 100,  # Sampling Rate(/100Hz).
+                48000 // 100,  # Sampling Rate(/100Hz).
                 0,  # Bitrate(unused).
                 1,  # Channels.
                 10000 // 10,  # Frame duration(/10us).
diff --git a/examples/run_vcp_renderer.py b/examples/run_vcp_renderer.py
new file mode 100644
index 0000000..b519bb6
--- /dev/null
+++ b/examples/run_vcp_renderer.py
@@ -0,0 +1,192 @@
+# Copyright 2021-2024 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
+#
+#      https://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.
+
+# -----------------------------------------------------------------------------
+# Imports
+# -----------------------------------------------------------------------------
+import asyncio
+import logging
+import sys
+import os
+import secrets
+import websockets
+import json
+
+from bumble.core import AdvertisingData
+from bumble.device import Device
+from bumble.hci import (
+    CodecID,
+    CodingFormat,
+    OwnAddressType,
+    HCI_LE_Set_Extended_Advertising_Parameters_Command,
+)
+from bumble.profiles.bap import (
+    CodecSpecificCapabilities,
+    ContextType,
+    AudioLocation,
+    SupportedSamplingFrequency,
+    SupportedFrameDuration,
+    PacRecord,
+    PublishedAudioCapabilitiesService,
+    AudioStreamControlService,
+)
+from bumble.profiles.cap import CommonAudioServiceService
+from bumble.profiles.csip import CoordinatedSetIdentificationService, SirkType
+from bumble.profiles.vcp import VolumeControlService
+
+from bumble.transport import open_transport_or_link
+
+from typing import Optional
+
+
+def dumps_volume_state(volume_setting: int, muted: int, change_counter: int) -> str:
+    return json.dumps(
+        {
+            'volume_setting': volume_setting,
+            'muted': muted,
+            'change_counter': change_counter,
+        }
+    )
+
+
+# -----------------------------------------------------------------------------
+async def main() -> None:
+    if len(sys.argv) < 3:
+        print('Usage: run_vcp_renderer.py <config-file>' '<transport-spec-for-device>')
+        return
+
+    print('<<< connecting to HCI...')
+    async with await open_transport_or_link(sys.argv[2]) as hci_transport:
+        print('<<< connected')
+
+        device = Device.from_config_file_with_hci(
+            sys.argv[1], hci_transport.source, hci_transport.sink
+        )
+
+        await device.power_on()
+
+        # Add "placeholder" services to enable Android LEA features.
+        csis = CoordinatedSetIdentificationService(
+            set_identity_resolving_key=secrets.token_bytes(16),
+            set_identity_resolving_key_type=SirkType.PLAINTEXT,
+        )
+        device.add_service(CommonAudioServiceService(csis))
+        device.add_service(
+            PublishedAudioCapabilitiesService(
+                supported_source_context=ContextType.PROHIBITED,
+                available_source_context=ContextType.PROHIBITED,
+                supported_sink_context=ContextType.MEDIA,
+                available_sink_context=ContextType.MEDIA,
+                sink_audio_locations=(
+                    AudioLocation.FRONT_LEFT | AudioLocation.FRONT_RIGHT
+                ),
+                sink_pac=[
+                    # Codec Capability Setting 48_4
+                    PacRecord(
+                        coding_format=CodingFormat(CodecID.LC3),
+                        codec_specific_capabilities=CodecSpecificCapabilities(
+                            supported_sampling_frequencies=(
+                                SupportedSamplingFrequency.FREQ_48000
+                            ),
+                            supported_frame_durations=(
+                                SupportedFrameDuration.DURATION_10000_US_SUPPORTED
+                            ),
+                            supported_audio_channel_counts=[1],
+                            min_octets_per_codec_frame=120,
+                            max_octets_per_codec_frame=120,
+                            supported_max_codec_frames_per_sdu=1,
+                        ),
+                    ),
+                ],
+            )
+        )
+        device.add_service(AudioStreamControlService(device, sink_ase_id=[1, 2]))
+
+        vcs = VolumeControlService()
+        device.add_service(vcs)
+
+        ws: Optional[websockets.WebSocketServerProtocol] = None
+
+        def on_volume_state(volume_setting: int, muted: int, change_counter: int):
+            if ws:
+                asyncio.create_task(
+                    ws.send(dumps_volume_state(volume_setting, muted, change_counter))
+                )
+
+        vcs.on('volume_state', on_volume_state)
+
+        advertising_data = (
+            bytes(
+                AdvertisingData(
+                    [
+                        (
+                            AdvertisingData.COMPLETE_LOCAL_NAME,
+                            bytes('Bumble LE Audio', 'utf-8'),
+                        ),
+                        (
+                            AdvertisingData.FLAGS,
+                            bytes(
+                                [
+                                    AdvertisingData.LE_GENERAL_DISCOVERABLE_MODE_FLAG
+                                    | AdvertisingData.BR_EDR_HOST_FLAG
+                                    | AdvertisingData.BR_EDR_CONTROLLER_FLAG
+                                ]
+                            ),
+                        ),
+                        (
+                            AdvertisingData.INCOMPLETE_LIST_OF_16_BIT_SERVICE_CLASS_UUIDS,
+                            bytes(PublishedAudioCapabilitiesService.UUID),
+                        ),
+                    ]
+                )
+            )
+            + csis.get_advertising_data()
+        )
+
+        await device.start_extended_advertising(
+            advertising_properties=(
+                HCI_LE_Set_Extended_Advertising_Parameters_Command.AdvertisingProperties.CONNECTABLE_ADVERTISING
+            ),
+            own_address_type=OwnAddressType.PUBLIC,
+            advertising_data=advertising_data,
+        )
+
+        async def serve(websocket: websockets.WebSocketServerProtocol, _path):
+            nonlocal ws
+            await websocket.send(
+                dumps_volume_state(vcs.volume_setting, vcs.muted, vcs.change_counter)
+            )
+            ws = websocket
+            async for message in websocket:
+                volume_state = json.loads(message)
+                vcs.volume_state_bytes = bytes(
+                    [
+                        volume_state['volume_setting'],
+                        volume_state['muted'],
+                        volume_state['change_counter'],
+                    ]
+                )
+                await device.notify_subscribers(
+                    vcs.volume_state, vcs.volume_state_bytes
+                )
+            ws = None
+
+        await websockets.serve(serve, 'localhost', 8989)
+
+        await hci_transport.source.terminated
+
+
+# -----------------------------------------------------------------------------
+logging.basicConfig(level=os.environ.get('BUMBLE_LOGLEVEL', 'DEBUG').upper())
+asyncio.run(main())
diff --git a/examples/vcp_renderer.html b/examples/vcp_renderer.html
new file mode 100644
index 0000000..c438950
--- /dev/null
+++ b/examples/vcp_renderer.html
@@ -0,0 +1,103 @@
+<html data-bs-theme="dark">
+
+<head>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/css/bootstrap.min.css" rel="stylesheet"
+        integrity="sha384-T3c6CoIi6uLrA9TneNEoa7RxnatzjcDSCmG1MXxSR1GAsXEV/Dwwykc2MPK8M2HN" crossorigin="anonymous">
+
+</head>
+
+<body>
+
+    <div class="container">
+
+        <label for="server-port" class="form-label">Server Port</label>
+        <div class="input-group mb-3">
+            <input type="text" class="form-control" aria-label="Port Number" value="8989" id="port">
+            <button class="btn btn-primary" type="button" onclick="connect()">Connect</button>
+        </div>
+
+        <div class="row">
+            <div class="col">
+                <label for="volume_setting" class="form-label">Volume Setting</label>
+                <input type="range" class="form-range" min="0" max="255" id="volume_setting">
+            </div>
+            <div class="col">
+                <label for="change_counter" class="form-label">Change Counter</label>
+                <input type="range" class="form-range" min="0" max="255" id="change_counter">
+            </div>
+            <div class="col">
+                <div class="form-check form-switch">
+                    <input class="form-check-input" type="checkbox" role="switch" id="muted">
+                    <label class="form-check-label" for="muted">Muted</label>
+                </div>
+            </div>
+        </div>
+
+        <button class="btn btn-primary" type="button" onclick="update_state()">Notify New Volume State</button>
+
+
+        <hr>
+        <div id="socketStateContainer" class="bg-body-tertiary p-3 rounded-2">
+            <h3>Log</h3>
+            <code id="socketState">
+            </code>
+        </div>
+    </div>
+
+    <script>
+        let portInput = document.getElementById("port")
+        let volumeSetting = document.getElementById("volume_setting")
+        let muted = document.getElementById("muted")
+        let changeCounter = document.getElementById("change_counter")
+        let socket = null
+
+        function connect() {
+            if (socket != null) {
+                return
+            }
+            socket = new WebSocket(`ws://localhost:${portInput.value}`);
+            socket.onopen = _ => {
+                socketState.innerText += 'OPEN\n'
+            }
+            socket.onclose = _ => {
+                socketState.innerText += 'CLOSED\n'
+                socket = null
+            }
+            socket.onerror = (error) => {
+                socketState.innerText += 'ERROR\n'
+                console.log(`ERROR: ${error}`)
+            }
+            socket.onmessage = (event) => {
+                socketState.innerText += `<- ${event.data}\n`
+                let volume_state = JSON.parse(event.data)
+                volumeSetting.value = volume_state.volume_setting
+                changeCounter.value = volume_state.change_counter
+                muted.checked = volume_state.muted ? true : false
+            }
+        }
+
+        function send(message) {
+            if (socket && socket.readyState == WebSocket.OPEN) {
+                let jsonMessage = JSON.stringify(message)
+                socketState.innerText += `-> ${jsonMessage}\n`
+                socket.send(jsonMessage)
+            } else {
+                socketState.innerText += 'NOT CONNECTED\n'
+            }
+        }
+
+        function update_state() {
+            send({
+                volume_setting: parseInt(volumeSetting.value),
+                change_counter: parseInt(changeCounter.value),
+                muted: muted.checked ? 1 : 0
+            })
+        }
+    </script>
+    <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/js/bootstrap.bundle.min.js"
+        integrity="sha384-C6RzsynM9kWDrMNeT87bh95OGNyZPhcTNXj1NW7RuBCsyN/o0jlpcV8Qyq46cDfL"
+        crossorigin="anonymous"></script>
+
+</body>
+
+</html>
\ No newline at end of file
diff --git a/tests/vcp_test.py b/tests/vcp_test.py
new file mode 100644
index 0000000..5accdc4
--- /dev/null
+++ b/tests/vcp_test.py
@@ -0,0 +1,122 @@
+# Copyright 2021-2023 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
+#
+#      https://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.
+
+# -----------------------------------------------------------------------------
+# Imports
+# -----------------------------------------------------------------------------
+import asyncio
+import os
+import pytest
+import logging
+
+from bumble import device
+from bumble import gatt
+from bumble.profiles import vcp
+from .test_utils import TwoDevices
+
+# -----------------------------------------------------------------------------
+# Logging
+# -----------------------------------------------------------------------------
+logger = logging.getLogger(__name__)
+
+
+# -----------------------------------------------------------------------------
+@pytest.fixture
+async def vcp_client():
+    devices = TwoDevices()
+    devices[0].add_service(
+        vcp.VolumeControlService(volume_setting=32, muted=1, volume_flags=1)
+    )
+
+    await devices.setup_connection()
+
+    # Mock encryption.
+    devices.connections[0].encryption = 1
+    devices.connections[1].encryption = 1
+
+    peer = device.Peer(devices.connections[1])
+    vcp_client = await peer.discover_service_and_create_proxy(
+        vcp.VolumeControlServiceProxy
+    )
+    yield vcp_client
+
+
+# -----------------------------------------------------------------------------
+@pytest.mark.asyncio
+async def test_init_service(vcp_client: vcp.VolumeControlServiceProxy):
+    assert (await vcp_client.volume_flags.read_value()) == 1
+    assert (await vcp_client.volume_state.read_value()) == (32, 1, 0)
+
+
+# -----------------------------------------------------------------------------
+@pytest.mark.asyncio
+async def test_relative_volume_down(vcp_client: vcp.VolumeControlServiceProxy):
+    await vcp_client.volume_control_point.write_value(
+        bytes([vcp.VolumeControlPointOpcode.RELATIVE_VOLUME_DOWN, 0])
+    )
+    assert (await vcp_client.volume_state.read_value()) == (16, 1, 1)
+
+
+# -----------------------------------------------------------------------------
+@pytest.mark.asyncio
+async def test_relative_volume_up(vcp_client: vcp.VolumeControlServiceProxy):
+    await vcp_client.volume_control_point.write_value(
+        bytes([vcp.VolumeControlPointOpcode.RELATIVE_VOLUME_UP, 0])
+    )
+    assert (await vcp_client.volume_state.read_value()) == (48, 1, 1)
+
+
+# -----------------------------------------------------------------------------
+@pytest.mark.asyncio
+async def test_unmute_relative_volume_down(vcp_client: vcp.VolumeControlServiceProxy):
+    await vcp_client.volume_control_point.write_value(
+        bytes([vcp.VolumeControlPointOpcode.UNMUTE_RELATIVE_VOLUME_DOWN, 0])
+    )
+    assert (await vcp_client.volume_state.read_value()) == (16, 0, 1)
+
+
+# -----------------------------------------------------------------------------
+@pytest.mark.asyncio
+async def test_unmute_relative_volume_up(vcp_client: vcp.VolumeControlServiceProxy):
+    await vcp_client.volume_control_point.write_value(
+        bytes([vcp.VolumeControlPointOpcode.UNMUTE_RELATIVE_VOLUME_UP, 0])
+    )
+    assert (await vcp_client.volume_state.read_value()) == (48, 0, 1)
+
+
+# -----------------------------------------------------------------------------
+@pytest.mark.asyncio
+async def test_set_absolute_volume(vcp_client: vcp.VolumeControlServiceProxy):
+    await vcp_client.volume_control_point.write_value(
+        bytes([vcp.VolumeControlPointOpcode.SET_ABSOLUTE_VOLUME, 0, 255])
+    )
+    assert (await vcp_client.volume_state.read_value()) == (255, 1, 1)
+
+
+# -----------------------------------------------------------------------------
+@pytest.mark.asyncio
+async def test_mute(vcp_client: vcp.VolumeControlServiceProxy):
+    await vcp_client.volume_control_point.write_value(
+        bytes([vcp.VolumeControlPointOpcode.MUTE, 0])
+    )
+    assert (await vcp_client.volume_state.read_value()) == (32, 1, 0)
+
+
+# -----------------------------------------------------------------------------
+@pytest.mark.asyncio
+async def test_unmute(vcp_client: vcp.VolumeControlServiceProxy):
+    await vcp_client.volume_control_point.write_value(
+        bytes([vcp.VolumeControlPointOpcode.UNMUTE, 0])
+    )
+    assert (await vcp_client.volume_state.read_value()) == (32, 0, 1)