Loadable Modules

The following loadable modules are provided with the polypaudio distribution:

Device Drivers

All device driver modules support the following parameters:

module-pipe-sink

Provides a simple test sink that writes the audio data to a FIFO special file in the file system. The sink name defaults to pipe_output.

The following option is supported:

module-pipe-source

Provides a simple test source that reads the audio data from a FIFO special file in the file system. The source name defaults to pipe_input.

The following option is supported:

module-null-sink

Provides a simple null sink. All data written to this sink is silently dropped. This sink is clocked using the system time.

This module doesn't support any special parameters

Provides a playback sink for devices supported by the Advanced Linux Sound Architecture (ALSA). The sink name defaults to alsa_output.

In addition to the general device driver options described above this module supports:

module-alsa-source

Provides a recording source for devices supported by the Advanced Linux Sound Architecture (ALSA). The source name defaults to alsa_input.

This module supports device=, fragments= and fragment_size= arguments the same way as module-alsa-sink.

Provides both a sink and a source for playback, resp. recording on Open Sound System (OSS) compatible devices.

This module supports device= (which defaults to /dev/dsp), fragments= and fragment_size= arguments the same way as module-alsa-sink.

In addition this module supports the following options:

The sink name (resp. source name) defaults to oss_output (resp. oss_input).

module-oss-mmap

Similar to module-oss but uses memory mapped (mmap()) access to the input/output buffers of the audio device. This provides better latency behaviour but is not as compatible as module-oss.

This module accepts exactly the same arguments as module-oss.

module-solaris

Provides a sink and source for the Solaris audio device.

In addition to the general device driver options described above this module supports:

module-waveout

Provides a sink and source for the Win32 audio device.

This module supports all arguments thet module-oss supports except device=.

module-combine

This combines two or more sinks into one. A new virtual sink is allocated. All data written to it is forwarded to all connected sinks. In aequidistant intervals the sample rates of the output sinks is recalculated: i.e. even when the sink's crystals deviate (which is normally the case) output appears synchronously to the human ear. The resampling required for this may be very CPU intensive.

module-tunnel-{sink,source}

Tunnel a remote sink/source to a local "ghost" sink/source. Requires a running polypaudio daemon on the remote server with module-native-protocol-tcp loaded. It's probably a better idea to connect to the remote sink/source directly since some buffer control is lost through this tunneling.

module-esound-sink

Create a playback sink using an ESOUND server as backend. Whenever you can, try to omit this module since it has many disadvantages including bad latency and even worse latency measurement.

Protocols

For an explanation of the simple command line language used by this module see cli.html.

This module doesn't accept any arguments.

An implemenation of a simple command line based protocol for controlling the polypaudio daemon. If loaded, the user may connect with tools like netcat, telnet or bidilink to the listening sockets and execute commands the same way as with module-cli.

Beware! Users are not authenticated when connecting to this service.

This module exists in two versions: with the suffix -unix the service will listen on an UNIX domain socket in the local file system. With the suffix -tcp it will listen on a network transparent TCP/IP socket. (Both IPv6 and IPv4 - if available)

This module supports the following options:

module-simple-protocol-{unix,tcp}

An implementation of a simple protocol which allows playback by using simple tools like netcat. Just connect to the listening socket of this module and write the audio data to it, or read it from it for playback, resp. recording.

Beware! Users are not authenticated when connecting to this service.

See module-cli-protocol-{unix,tcp} for more information about the two possible suffixes of this module.

In addition to the options supported by module-cli-protocol-*, this module supports:

module-esound-protocol-{unix,tcp}

An implemenation of a protocol compatible with the Enlightened Sound Daemon (ESOUND, esd). When you load this module you may access the polypaudio daemon with tools like esdcat, esdrec or even esdctl. Many applications, such as XMMS, include support for this protocol.

See module-cli-protocol-{unix,tcp} for more information about the two possible suffixes of this module.

In addition to the options supported by module-cli-protocol-*, this module supports:

This implementation misses some features the original ESOUND has: e.g. there is no sample cache yet. However: XMMS works fine.

module-native-protocol-{unix,tcp}

The native protocol of polypaudio.

See module-cli-protocol-{unix,tcp} for more information about the two possible suffixes of this module.

In addition to the options supported by module-cli-protocol-*, this module supports:

module-native-protocol-fd

This is used internally when auto spawning a new daemon. Don't use it directly.

module-http-protocol-tcp

A proof-of-concept HTTP module, which can be used to introspect the current status of the polypaudio daemon using HTTP. Just load this module and point your browser to http://localhost:4714/. This module takes the same arguments as module-cli-protocol-tcp.

X Window System

module-x11-bell

Intercepts X11 bell events and plays a sample from the sample cache on each occurence.

module-x11-publish

Publishes the access credentials to the Polypaudio server in the X11 root window. The following properties are used: POLYP_SERVER, POYLP_SINK, POLYP_SOURCE, POLYP_COOKIE. This is very useful when using SSH or any other remote login tool for logging into other machines and getting audio playback to your local speakers. The Polypaudio client libraries make use of this data automatically. Instead of using this module you may use the tool pax11publish which may be used to access, modify and import credential data from/to the X11 display.

Volume Control

module-mmkbd-evdev

Adjust the volume of a sink when the special multimedia buttons of modern keyboards are pressed.

module-lirc

Adjust the volume of a sink when the volume buttons of an infrared remote control are pressed (through LIRC).

Polypaudio can stream audio data to an IP multicast group via the standard protocols RTP, SAP and SDP (RFC3550, RFC3551, RFC2327, RFC2327). This can be used for multiple different purposes: for sharing a single microphone on multiple computers on the local LAN, for streaming music from a single controlling PC to multiple PCs with speakers or to implement a simple "always-on" teleconferencing solution.

The current implementation is designed to be used exlusively in local area networks, though Internet multicasting is theoretically supported. Only uncompressed audio is supported, hence you won't be able to multicast more than a few streams at the same time over a standard LAN.

Polypaudio implements both a sender and a reciever for RTP traffic. The sender announces itself via SAP/SDP on the same multicast group as it sends the RTP data to. The reciever picks up the SAP/SDP announcements and creates a playback stream for each session. Alternatively you can use any RTP capable client to recieve and play back the RTP data (such as mplayer).

module-rtp-send

This is the sender side of the RTP/SDP/SAP implementation. It reads audio data from an existing source and forwards it to the network encapsulated in RTP. In addition it sends SAP packets with an SDP session description.

In combination with the monitor source of module-null-sink you can use this module to create an RTP sink.

module-rtp-recv

This is the reciever side of the RTP/SDP/SAP implementation. It picks up SAP session announcements and creates an RTP playback stream for each.

In combination with module-null-sink you can use this module to create an RTP source.

Miscellaneous

module-sine

Creates a sink input and generates a sine waveform stream.

module-esound-compat-spawnfd

This is a compatibility module for libesd based autospawning of polypaudio. Don't use it directly.

module-esound-compat-spawnpid

This is a compatibility module for libesd based autospawning of polypaudio. Don't use it directly.

module-match

Adjust the volume of a playback stream automatically based on its name.

The table file should contain a regexp and volume on each line, seperated by spaces. An example:

^sample: 25

The volumes of all streams with titles starting with sample: are automatically set to 25. (FYI: All sample cache streams start with sample:)

module-detect

Automatically detect the available sound hardware and load modules for it. Supports OSS, ALSA, Solaris and Win32 output drivers.

module-zeroconf-publish

Publish all local sinks/sources using mDNS Zeroconf.