libparsec

⚡ The imaginary Parsec SDK
Low latency, peer-to-peer, interactive game streaming.

🚧 Working in progress

The goal is single header for C/C++, and Rust bindings. Output binaries would be static lib and dynamic lib (DLL).

F**k this $320M acquisition!

Target platforms

• Windows (64-bit)
• Linux
• macOS

Client features

• Hardware decoders
• FFmpeg decoder (smaller build)
• HEVC codec
• YUV420, YUV444
• 10-bit color

Instance functions

• ParsecInit
• ParsecDestroy
• ParsecGetConfig
• ParsecGetBuffer
• ParsecFree
• ParsecSetLogCallback
• ParsecVersion
• ParsecGetOutputs
• ParsecGetAudioOutputs
• ParsecGetDecoders
• ParsecJSONCommand
• ParsecCanHost
• ParsecGetVUSBState (not supported)
• ParsecGetVDDState (not supported)
• ParsecSetConfig

Client functions

• ParsecClientConnect (removed in new SDK)
• ParsecClientDisconnect
• ParsecClientGetStatus
• ParsecClientGetGuests
• ParsecClientSetConfig
• ParsecClientSetDimensions
• ParsecClientPollFrame
• ParsecClientPollAudio
• ParsecClientPollEvents
• ParsecClientGLDestroy (deprecated)
• ParsecClientSendMessage
• ParsecClientPause
• ParsecClientEnableStream
• ParsecClientSendUserData
• ParsecClientSendExtraData
• ParsecClientScalePenMessage (not supported)
• ParsecClientSendVirtualUSB (not supported)

Host functions

HOST_DESKTOP only.

• ParsecHostStart
• ParsecHostStop
• ParsecHostGetStatus
• ParsecHostSetConfig
• ParsecHostGetGuests
• ParsecHostKickGuest
• ParsecHostSendUserData
• ParsecHostSendUserDataAll
• ParsecHostBeginP2P
• ParsecHostSetPermissions

Signal functions

Signal server and these functions are used to control the handshake flow.
This is a way to build your own server without relying on the Parsec's online service.

sequenceDiagram
    participant Client
    participant STUN_Server as STUN Server
    participant Host
    participant Signal_API as Signal API
    
    Client->>STUN_Server: Start UDP conversation (port 3478)
    STUN_Server-->>Client: Respond with public IP & listener port
    Client->>Signal_API: Send connection info via WebSocket
    Host->>STUN_Server: Start UDP conversation (port 3478)
    STUN_Server-->>Host: Respond with public IP & listener port
    Host->>Signal_API: Send connection info via WebSocket
    Signal_API-->>Client: Host's connection info
    Signal_API-->>Host: Client's connection info
    Client->>Host: Attempt connection
    Host->>Client: Attempt connection
    Note over Client, Host: Connection established based on NAT traversal success

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• ParsecSignalInit
• ParsecSignalDestroy
• ParsecSignalUpdateHost
• ParsecSignalConnect
• ParsecSignalDisconnect
• ParsecSignalSendCandidate
• ParsecClientNewAttempt
• ParsecClientAddCandidate
• ParsecClientBeginP2P
• ParsecClientEndConnection

Signal callbacks:

• ParsecSignalOpenCallback
• ParsecSignalErrorCallback
• ParsecSignalAnswerCallback
• ParsecSignalCandexCallback
• ParsecSignalSdkCallback

WebRTC client implementation

SCTP is a side protocol of Parsec host implementation that allows WebRTC connection.

The client should meet:

• SCTP-based Data Channels (RFC8831)
• DTLS/UDP (RFC7350 and RFC8261)
• DTLS with ECDSA (RFC8827)

sequenceDiagram
    participant Client
    participant SignalServer
    participant Host
    participant Proto
    participant Parsec

    Client->>SignalServer: NewAttempt (request to connect)
    SignalServer->>Host: Notify of incoming connection
    Host->>SignalServer: Ready to accept
    SignalServer->>Client: Host is ready

    Client->>Proto: CreateOffer
    Proto->>Client: SDP Offer
    Client->>SignalServer: SendOffer (SDP Offer)
    SignalServer->>Host: ForwardOffer (SDP Offer)
    Host->>Proto: ReceiveOffer (SDP Offer)
    Proto->>Host: CreateAnswer
    Host->>SignalServer: SendAnswer (SDP Answer)
    SignalServer->>Client: ForwardAnswer (SDP Answer)
    Client->>Proto: ReceiveAnswer (SDP Answer)

    loop ICE Candidate Exchange
        Client->>SignalServer: AddCandidate (ICE Candidate)
        SignalServer->>Host: ForwardCandidate (ICE Candidate)
        Host->>Proto: AddCandidate (ICE Candidate)

        Host->>SignalServer: AddCandidate (ICE Candidate)
        SignalServer->>Client: ForwardCandidate (ICE Candidate)
        Client->>Proto: AddCandidate (ICE Candidate)
    end

    Proto->>Parsec: Establish Secure Channel
    Parsec->>Proto: Ready
    Client->>Host: Parsec Data Channel Established

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