Network SID Device

Implementation of a network SID device protocol

You can implement your own SID device (hardware or software based) and control it using JSIDPlay2. The network SID device protocol has been defined to communicate with these implementations.

This protocol is called: Network SID device protocol. Communication is done via socket connection and port 6581 by default.

JSIDPlay2 can act as a client or as a server:

  1. JSIDPlay2 is able to use these SID implementations as a client to playback SID on these devices.

  2. JSIDPlay2 also provides such a device (Network SID Device) implementing the network SID device protocol to be used with other software (e.g. ACID64)

General Overview

Since version 2, the protocol is structured as a request-response protocol:

  • Requests are variable length, with minimum packet size 4 bytes. There are 3 fields and an amorphous data blob:

    • 8-bit unsigned as command.

    • 8-bit unsigned as SID number.

    • 16-bit unsigned as length of data attached to header in bytes.

    • Data (if any)

  • All commands are ACKed with a response packet that takes one of the following forms:

    • OK means that the commands were accepted by server and can be discarded by client. No data will be appended to response.

    • BUSY means that no part of the current command was accepted due to filled queue condition, and that client should wait and retry it later. 1 millisecond could be a suitable delay before retry. Queue length is limited both by number of events and maximum time drift between playback clock and client clock. No data will be attended to response.

    • READ: successful read operation, one byte value follows that is the value read from SID.

    • VERSION: response to VERSION operation. Version number will be appended to response.

    • COUNT: number of SIDs supported by network device.

    • INFO: info packet, which contains model code and zero-padded 20-byte UTF-8 encoded string representing model name.

  • Maximum packet length is 64k + header length. It is suggested that only short packets are transmitted, in the order of 1k and containing no more than about 1 ms worth of events. Otherwise the client-server desync brings jitter that may have unpleasant consequences. At the limit it’s possible to simply send a fixed header that describes a single write with each packet, but this is probably measurably less efficient.

Protocol version information

  • Version 1

    • contains commands FLUSH, TRY_SET_SID_COUNT, MUTE, TRY_RESET, TRY_DELAY, TRY_WRITE, TRY_READ and GET_VERSION. There are 8 SID devices where bit 0 sets 6581/8580, bit 1 sets PAL/NTSC and bit 2 sets RESAMPLE/DECIMATE mode of operation.

  • Version 2

    • contains commands TRY_SET_SAMPLING, TRY_SET_CLOCKING, GET_CONFIG_COUNT, GET_CONFIG_INFO, SET_SID_POSITION, SET_SID_LEVEL, TRY_SET_SID_MODEL. There are multiple SID devices of type 6581 and 8580. The commands TRY_SET_SAMPLING and TRY_SET_CLOCKING can be used to set particular SID kind.

  • Version 3

    • supports muting of voice number 4 (digi channel).

  • Version 4

    • contains commands SET_DELAY, SET_FADE_IN, SET_FADE_OUT and SET_SID_HEADER.

Command Overview

  • Structure of data is specific to command. Some commands require data, others will not use data even if such was provided. Some commands require specific lengths for the data packets. If data length is not correct, results are undefined. Known commands are identified by small integers, starting from 0:

    • FLUSH (0): destroy queued data on all SIDs, and cease audio production.

      • sid number is ignored.

      • data packet must be 0 length.

      • should probably be followed by RESET (SID is in unpredictable state).

      • always returns OK

    • TRY_SET_SID_COUNT (1): set number of SID devices available for writing

      • sid number equals the count of SIDs wanted.

      • data packet must be 0 length.

      • returns BUSY until audio quiescent, otherwise OK.

    • MUTE (2): mute/unmute a voice on specified SID

      • data packet must contain two 8-bit unsigned bytes:

        • the voice number from 0 to 3 (voice number 3 (digi) is supported since version 3. For version 2 of the protocol only voice numbers 0 to 2 are supported.

        • 0 or 1 to disable/enable voice

      • this command bypasses buffer and takes immediate effect.

      • always returns OK

    • TRY_RESET (3): reset all SIDs, setting volume to provided value.

      • data packet must be a 8-bit unsigned value which is written to volume register.

      • returns BUSY until audio quiescent, otherwise OK.

    • TRY_DELAY (4): inform emulation that no events have occurred for a given count of cycles

      • data packet must be 16-bit unsigned value interpreted as delay in C64 clocks. 0 is not allowed.

      • allows audio generation in absence of other activity.

      • returns BUSY if there is already enough data for playback, otherwise OK.

    • TRY_WRITE (5): try to queue a number of write-to-sid events.

      • data packet must be 4*N bytes long, repeating this structure:

        • 16-bit unsigned value interpreted as delay before the write in C64 clocks.

        • 8-bit unsigned SID register number from 0x00 to 0x1f.

        • 8-bit unsigned data value to write

      • returns BUSY if there is already enough data for playback, otherwise OK.

    • TRY_READ (6): reads SID chip register.

      • data packet must be a 4n+3 bytes long, where n >= 0. The protocol used for the first n packets is the same as the TRY_WRITE protocol, returning potentially BUSY if the delay implied by the READ, or the WRITEs can not yet be buffered.

      • Read packet structure trails the write packet structure:

        • 16-bit unsigned value interpreted as delay before the read in C64 clocks.

        • 8-bit unsigned SID register number from 0x00 to 0x1f.

      • returns BUSY if there is already enough data for playback, otherwise READ and a data byte, which is the read value from SID.

    • GET_VERSION (7): returns the version of the SID Network protocol.

      • sid number is ignored.

      • data packet must be 0 length.

      • returns 2 bytes: VERSION and a data byte, which is the version of the SID Network protocol.

    • TRY_SET_SAMPLING (8): set the resampling method for all SID devices.

      • sid number is ignored.

      • data packet is 1 byte long and contains:

        • 0 for pure decimator (low quality)

        • 1 for low-pass filtered decimator (high quality).

      • returns BUSY until audio quiescent, otherwise OK.

    • SET_CLOCKING (9): set the clock source speed for all SID devices.

      • sid number is ignored.

      • data packet is 1 byte long and contains:

        • 0 for PAL

        • 1 for NTSC

      • returns BUSY until audio quiescent, otherwise OK.

    • GET_CONFIG_COUNT (10): Query number of SID configurations supported by server.

      • sid number is ignored.

      • data packet is ignored and should be 0 length.

      • always returns COUNT and a 8-bit unsigned value that is 1 larger than the maximum valid configuration.

    • GET_CONFIG_INFO (11): query the name and model of the SID configuration.

      • data packet is ignored and should be 0 length.

      • returns INFO and 8-bit unsigned-value and a string in ISO-8859-1 encoding with a maximum of 255 characters excluding a null terminated byte

        • INFO code

        • Model: 0 = 6581, 1 = 8580

        • Model name (max. 255 chars + 1 null terminated byte)

    • SET_SID_POSITION (12): set sid position on the audio mix

      • data packet is 1 byte long and contains:

        • -100 to 0: audio is panned to left

        • 0 to 100: audio is panned to right

      • always returns OK.

    • SET_SID_LEVEL (13): set SID level adjustment in dB

      • data packet is 1 byte long and contains:

        • 8-bit signed dB adjustment in cB (centibels), 0 means no adjustment

      • always returns OK.

    • SET_SID_MODEL (14):

      • data packet is 1 byte long and contains:

        • 8-bit unsigned value between 0 <= value <= max_config-1

      • always returns OK.

    • SET_DELAY (15): set SID output delay in ms

      • data packet is 1 byte long and contains:

        • 8-bit unsigned ms delay, 0 means no delay

      • always returns OK.

    • SET_FADE_IN (16): set fade-in time in ms.

      • sid number is ignored.

      • data packet is 4 bytes long and contains:

        • 32-bit unsigned fade-in time in milliseconds.

        • Note: Since only the client knows the song length, you must send this command, when the fade-in time is reached (at the start of the tune).

      • returns BUSY until audio quiescent, otherwise OK.

    • SET_FADE_OUT (17): set fade-out time in ms.

      • sid number is ignored.

      • data packet is 4 bytes long and contains:

        • 32-bit unsigned fade-out time in milliseconds.

        • Note: Since only the client knows the song length, you must send this command, when the fade-out time is reached (near the end of the tune).

      • returns BUSY until audio quiescent, otherwise OK.

    • SET_SID_HEADER (18): set SID header bytes

      • data packet is at least 124 bytes long and depends on the size of the SID header. It contains:

        • SID header bytes. This optional command can be used to show information of what is currently being played.

      • always returns OK.

Make use of devices implementing the network SID device protocol (JSIDPlay2 as a Client)

To use these SID implementations as a client for playback, you must choose NetSID as the emulation type in the user interface and provide a hostname and port for that. Default is to connect to 127.0.0.1:6581.

E.g you can use ConsolePlayer to use these SID implementations for playback.

java -jar jsidplay2-console-4.6.jar \
	--engine NETSID \
	--NetSIDDevHost 127.0.0.1 \
	--NetSIDDevPort 6581 (1)
  1. Start ConsolePlayer and use Network SID Device for sound output

Launch Network SID Device (JSIDPlay2 as a Server)

It is possible to have JSIDPlay2 take over the duty of the SID playback for a C64 emulator/player. The Network SID Device tries to open port 6581 where it will listen to connections that describe SID activity.

Note: Whereas Windows users get an executable (.EXE) to launch…​

jsiddevice-4.6.exe (1)
  1. Launch User interface version (console version is not available as an executable, see below)

…​other operating systems launch Network SID Device using the following command:

java -jar jsiddevice-4.6.jar (1)
java -classpath jsiddevice-4.6.jar server.netsiddev.NetworkSIDDevice (2)
  1. Launch User interface version

  2. Launch Console version