pandora/a2dp.proto

// Copyright 2022 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.

syntax = "proto3";

package pandora;

import "pandora/host.proto";
import "google/protobuf/empty.proto";
import "google/protobuf/wrappers.proto";

option java_outer_classname = "A2DPProto";

// Service to trigger A2DP (Advanced Audio Distribution Profile) procedures.
//
// Requirements for the implementer:
// - Streams must not be automatically opened, even if discovered.
// - The `Host` service must be implemented
//
// References:
// - [A2DP] Bluetooth SIG, Specification of the Bluetooth System,
//    Advanced Audio Distribution, Version 1.3 or Later
// - [AVDTP] Bluetooth SIG, Specification of the Bluetooth System,
//    Audio/Video Distribution Transport Protocol, Version 1.3 or Later
service A2DP {
  // Open a stream from a local **Source** endpoint to a remote **Sink**
  // endpoint.
  //
  // The returned source should be in the AVDTP_OPEN state (see [AVDTP] 9.1).
  // The rpc must block until the stream has reached this state.
  //
  // A cancellation of this call must result in aborting the current
  // AVDTP procedure (see [AVDTP] 9.9).
  rpc OpenSource(OpenSourceRequest) returns (OpenSourceResponse);
  // Open a stream from a local **Sink** endpoint to a remote **Source**
  // endpoint.
  //
  // The returned sink must be in the AVDTP_OPEN state (see [AVDTP] 9.1).
  // The rpc must block until the stream has reached this state.
  //
  // A cancellation of this call must result in aborting the current
  // AVDTP procedure (see [AVDTP] 9.9).
  rpc OpenSink(OpenSinkRequest) returns (OpenSinkResponse);
  // Wait for a stream from a local **Source** endpoint to
  // a remote **Sink** endpoint to open.
  //
  // The returned source should be in the AVDTP_OPEN state (see [AVDTP] 9.1).
  // The rpc must block until the stream has reached this state.
  //
  // If the peer has opened a source prior to this call, the server will
  // return it. The server must return the same source only once.
  rpc WaitSource(WaitSourceRequest) returns (WaitSourceResponse);
  // Wait for a stream from a local **Sink** endpoint to
  // a remote **Source** endpoint to open.
  //
  // The returned sink should be in the AVDTP_OPEN state (see [AVDTP] 9.1).
  // The rpc must block until the stream has reached this state.
  //
  // If the peer has opened a sink prior to this call, the server will
  // return it. The server must return the same sink only once.
  rpc WaitSink(WaitSinkRequest) returns (WaitSinkResponse);
  // Get if the stream is suspended
  rpc IsSuspended(IsSuspendedRequest) returns (google.protobuf.BoolValue);
  // Start an opened stream.
  //
  // The rpc must block until the stream has reached the
  // AVDTP_STREAMING state (see [AVDTP] 9.1).
  rpc Start(StartRequest) returns (StartResponse);
  // Suspend a streaming stream.
  //
  // The rpc must block until the stream has reached the AVDTP_OPEN
  // state (see [AVDTP] 9.1).
  rpc Suspend(SuspendRequest) returns (SuspendResponse);
  // Close a stream, the source or sink tokens must not be reused afterwards.
  rpc Close(CloseRequest) returns (CloseResponse);
  // Get the `AudioEncoding` value of a stream
  rpc GetAudioEncoding(GetAudioEncodingRequest)
      returns (GetAudioEncodingResponse);
  // Playback audio by a `Source`
  rpc PlaybackAudio(stream PlaybackAudioRequest)
      returns (PlaybackAudioResponse);
  // Capture audio from a `Sink`
  rpc CaptureAudio(CaptureAudioRequest) returns (stream CaptureAudioResponse);
}

// Audio encoding formats.
enum AudioEncoding {
  // Interleaved stereo frames with 16-bit signed little-endian linear PCM
  // samples at 44100Hz sample rate
  PCM_S16_LE_44K1_STEREO = 0;
  // Interleaved stereo frames with 16-bit signed little-endian linear PCM
  // samples at 48000Hz sample rate
  PCM_S16_LE_48K_STEREO = 1;
}

// A Token representing a Source stream (see [A2DP] 2.2).
// It's acquired via an OpenSource on the A2DP service.
message Source {
  // Opaque value filled by the GRPC server, must not
  // be modified nor crafted.
  bytes cookie = 1;
}

// A Token representing a Sink stream (see [A2DP] 2.2).
// It's acquired via an OpenSink on the A2DP service.
message Sink {
  // Opaque value filled by the GRPC server, must not
  // be modified nor crafted.
  bytes cookie = 1;
}

// Request for the `OpenSource` method.
message OpenSourceRequest {
  // The connection that will open the stream.
  Connection connection = 1;
}

// Response for the `OpenSource` method.
message OpenSourceResponse {
  // Result of the `OpenSource` call.
  oneof result {
    // Opened stream.
    Source source = 1;
    // The Connection disconnected.
    google.protobuf.Empty disconnected = 2;
  }
}

// Request for the `OpenSink` method.
message OpenSinkRequest {
  // The connection that will open the stream.
  Connection connection = 1;
}

// Response for the `OpenSink` method.
message OpenSinkResponse {
  // Result of the `OpenSink` call.
  oneof result {
    // Opened stream.
    Sink sink = 1;
    // The Connection disconnected.
    google.protobuf.Empty disconnected = 2;
  }
}

// Request for the `WaitSource` method.
message WaitSourceRequest {
  // The connection that is awaiting the stream.
  Connection connection = 1;
}

// Response for the `WaitSource` method.
message WaitSourceResponse {
  // Result of the `WaitSource` call.
  oneof result {
    // Awaited stream.
    Source source = 1;
    // The Connection disconnected.
    google.protobuf.Empty disconnected = 2;
  }
}

// Request for the `WaitSink` method.
message WaitSinkRequest {
  // The connection that is awaiting the stream.
  Connection connection = 1;
}

// Response for the `WaitSink` method.
message WaitSinkResponse {
  // Result of the `WaitSink` call.
  oneof result {
    // Awaited stream.
    Sink sink = 1;
    // The Connection disconnected.
    google.protobuf.Empty disconnected = 2;
  }
}

// Request for the `IsSuspended` method.
message IsSuspendedRequest {
  // The stream on which the function will check if it's suspended
  oneof target {
    Sink sink = 1;
    Source source = 2;
  }
}

// Request for the `Start` method.
message StartRequest {
  // Target of the start, either a Sink or a Source.
  oneof target {
    Sink sink = 1;
    Source source = 2;
  }
}

// Response for the `Start` method.
message StartResponse {
  // Result of the `Start` call.
  oneof result {
    // Stream successfully started.
    google.protobuf.Empty started = 1;
    // Stream is already in AVDTP_STREAMING state.
    google.protobuf.Empty already_started = 2;
    // The Connection disconnected.
    google.protobuf.Empty disconnected = 3;
  }
}

// Request for the `Suspend` method.
message SuspendRequest {
  // Target of the suspend, either a Sink or a Source.
  oneof target {
    Sink sink = 1;
    Source source = 2;
  }
}

// Response for the `Suspend` method.
message SuspendResponse {
  // Result of the `Suspend` call.
  oneof result {
    // Stream successfully suspended.
    google.protobuf.Empty suspended = 1;
    // Stream is already in AVDTP_OPEN state.
    google.protobuf.Empty already_suspended = 2;
    // The Connection disconnected.
    google.protobuf.Empty disconnected = 3;
  }
}

// Request for the `Close` method.
message CloseRequest {
  // Target of the close, either a Sink or a Source.
  oneof target {
    Sink sink = 1;
    Source source = 2;
  }
}

// Response for the `Close` method.
message CloseResponse {}

// Request for the `GetAudioEncoding` method.
message GetAudioEncodingRequest {
  // The stream on which the function will read the `AudioEncoding`.
  oneof target {
    Sink sink = 1;
    Source source = 2;
  }
}

// Response for the `GetAudioEncoding` method.
message GetAudioEncodingResponse {
  // Audio encoding of the stream.
  AudioEncoding encoding = 1;
}

// Request for the `PlaybackAudio` method.
message PlaybackAudioRequest {
  // Source that will playback audio.
  Source source = 1;
  // Audio data to playback.
  // The audio data must be encoded in the specified `AudioEncoding` value
  // obtained in response of a `GetAudioEncoding` method call.
  bytes data = 2;
}

// Response for the `PlaybackAudio` method.
message PlaybackAudioResponse {}

// Request for the `CaptureAudio` method.
message CaptureAudioRequest {
  // Sink that will capture audio
  Sink sink = 1;
}

// Response for the `CaptureAudio` method.
message CaptureAudioResponse {
  // Captured audio data.
  // The audio data is encoded in the specified `AudioEncoding` value
  // obtained in response of a `GetAudioEncoding` method call.
  bytes data = 1;
}