PulseAudio modules for Roc Toolkit

• What is this?
• Build instructions
• Running receiver
• Running sender
• Setting source or sink name
• Interoperability
• Troubleshooting
• Authors
• License

What is this?

This repo provides a set of PulseAudio modules enabling it to use Roc Toolkit as a network transport and improve its service quality over an unreliable network such as Wi-Fi.

Advantages over Roc command-line tools:

• Seamless integration into the PulseAudio workflow. The user can connect a local audio stream to a remote audio device using common PulseAudio tools like pavucontrol.

• A bit lower latency. Since Roc is integrated into the PulseAudio server, there is no additional communication step between Roc and PulseAudio server.

Advantages over PulseAudio "native" protocol:

• Better service quaility when the latency is low and the network is unreliable. PulseAudio "native" protocol uses TCP, while Roc uses RTP, which is better suited for real-time communication than TCP-based protocols.

• Compatibility with standard protocols. PulseAudio "native" protocol is PulseAudio-specific, while Roc implements a set of standardized RTP-based protocols.

Advantages over PulseAudio built-in RTP support:

• Better service quaility when the latency is low and the network is unreliable. PulseAudio uses bare RTP, while Roc also employs Forward Erasure Correction extensions.

Build instructions

Simple build

When using this method, CMake will automatically download and build dependencies (Roc Toolkit, PulseAudio, libtool). Roc will be statically linked into the modules and there is no need to install it into the system.

First install build tools and PulseAudio:

sudo apt install -y \
    gcc g++ \
    make \
    libtool intltool m4 autoconf automake \
    meson libsndfile-dev \
    cmake \
    scons \
    git \
    wget \
    python3 \
    pulseaudio

Then build PulseAudio modules:

make

And then install modules into the system:

sudo make install

Advanced build

You can disable automatic downloading of dependencies and build them manually.

First, download, build and install Roc Toolkit into the system as described on this page.

Then download and unpack PulseAudio source code from here. There is no need to configure and build it, only source code is needed.

Note: PulseAudio doesn't provide official API for out-of-tree modules. This is the reason why we need full PulseAudio source code to build modules.

Note: PulseAudio source code should have exactly the same version as the actual PulseAudio daemon which will be used to load modules.

Optionally, download and unpack libtool. As with PulseAudio, there is no need to build it. Alternatively, install it into the system using your package manager.

Then you can build and install modules:

mkdir build/native
cd build/native
cmake ../.. \
  -DDOWNLOAD_ROC=OFF \
  -DDOWNLOAD_PULSEAUDIO=OFF \
  -DDOWNLOAD_LIBTOOL=OFF \
  -DPULSEAUDIO_DIR=<...> \
  -DPULSEAUDIO_VERSION=<...>
make VERBOSE=1
sudo make install

Don't forget to specify correct PULSEAUDIO_VERSION!

If you've installed Roc Toolkit to non-standard directory, you can use -DROC_INCLUDE_DIR=<...> and -DROC_LIB_DIR=<...>. If you want to use custom libtool instead of the one from system, you can use -DLIBTOOL_DIR=<...>.

Cross-compilation

For simple cases, you can do everything automaticaly by specifying just two environment variables:

TOOLCHAIN_PREFIX=<...> PULSEAUDIO_VERSION=<...> make

For more granular configuration, you can invoke CMake directly:

mkdir build/cross
cd build/cross
cmake ../.. -DTOOLCHAIN_PREFIX=<...> -DPULSEAUDIO_VERSION=<...>
make VERBOSE=1

Commands above will cross-compile PulseAudio modules, as well as download and cross-compile their dependencies. Dependencies will be statically linked into modules. Modules will be installed into ./bin.

In these commands, TOOLCHAIN_PREFIX defines toolchain triple of the target system, e.g. aarch64-linux-gnu. In this case aarch64-linux-gnu-gcc and other tools should be available in PATH.

For more complicated cases, refer to standard instructions for cross-compiling using CMake.

Prebuilt toolchains

You can use one of our docker images with prebuilt cross-compilation toolchains. The commands below will cross-compile PulseAudio modules and install them to ./bin.

Raspberry Pi (64-bit):

docker run -t --rm -u "${UID}" -v "${PWD}:${PWD}" -w "${PWD}" \
  rocstreaming/toolchain-aarch64-linux-gnu \
    env TOOLCHAIN_PREFIX=aarch64-linux-gnu PULSEAUDIO_VERSION=<...> make

Raspberry Pi 2 and later (32-bit):

docker run -t --rm -u "${UID}" -v "${PWD}:${PWD}" -w "${PWD}" \
  rocstreaming/toolchain-arm-linux-gnueabihf \
    env TOOLCHAIN_PREFIX=arm-linux-gnueabihf PULSEAUDIO_VERSION=<...> make

Raspberry Pi 1 and Zero (32-bit):

docker run -t --rm -u "${UID}" -v "${PWD}:${PWD}" -w "${PWD}" \
  rocstreaming/toolchain-arm-bcm2708hardfp-linux-gnueabi \
    env TOOLCHAIN_PREFIX=arm-bcm2708hardfp-linux-gnueabi PULSEAUDIO_VERSION=<...> make

Running receiver

For the receiving side, use module-roc-sink-input PulseAudio module. It creates a PulseAudio sink input that receives samples from Roc sender and passes them to the sink it is connected to. You can then connect it to any audio device.

Roc sink input supports several options:

option	required	default	description
sink	no	<default sink>	the name of the sink to connect the new sink input to
sink_input_properties	no	empty	additional sink input properties
resampler_profile	no	medium	resampler mode, supported values: high, medium, low
sess_latency_msec	no	200	target session latency in milliseconds
io_latency_msec	no	40	target playback latency in milliseconds
local_ip	no	0.0.0.0	local address to bind to
local_source_port	no	10001	local port for source (audio) packets
local_repair_port	no	10002	local port for repair (FEC) packets
local_control_port	no	10003	local port for control (RTCP) packets

Here is how you can create a Roc sink input from command line:

pactl load-module module-roc-sink-input

Alternatively, you can add this line to /etc/pulse/default.pa to create a Roc sink input automatically at PulseAudio start:

load-module module-roc-sink-input

You can then connect the Roc sink input to an audio device (i.e. a sink) via command line:

# determine Roc sink-input number
pactl list sink-inputs

# connect Roc sink-input to a sink
pactl move-sink-input <roc_sink_input_number> <sink>

Or via the pavucontrol graphical tool:

Running sender

For the sending side, use module-roc-sink PulseAudio module. It creates a PulseAudio sink that sends samples written to it to a preconfigured receiver address. You can then connect an audio stream of any running application to that sink, or make it the default sink.

Roc sink supports several options:

option	required	default	description
sink_name	no	roc_sender	the name of the new sink
sink_properties	no	empty	additional sink properties
remote_ip	yes	no	remote receiver address
remote_source_port	no	10001	remote receiver port for source (audio) packets
remote_repair_port	no	10002	remote receiver port for repair (FEC) packets
remote_control_port	no	10003	remote receiver port for control (RTCP) packets

Here is how you can create a Roc sink from command line:

pactl load-module module-roc-sink remote_ip=<receiver_ip>

Alternatively, you can add this line to /etc/pulse/default.pa to create a Roc sink automatically at PulseAudio start:

load-module module-roc-sink remote_ip=<receiver_ip>

You can then connect an audio stream (i.e. a sink input) to the Roc sink via command line:

pactl move-sink-input <sink_input_number> roc_sender

Or via the pavucontrol graphical tool:

Setting source or sink name

PulseAudio sinks and sink inputs have name and description. Name is usually used when the sink or sink input is referenced from command-line tools or configuration files, and description is shown in the GUI.

Sink name and description can be configured via sink_name module argument and device.description sink property set by sink_properties module argument:

pactl load-module module-roc-sink remote_ip=192.168.1.38 \
  sink_name=my_name sink_properties=device.description=My-Description

Sink input name and description can be configured via sink_input_name module argument and media.name sink input property set by sink_input_properties module argument:

pactl load-module module-roc-sink-input \
  sink_input_name=my_name sink_input_properties=media.name=My-Description

Interoperability

These PulseAudio modules are interoperable with Roc library command line tools, i.e.:

• as a sender, you can use either roc_sender from the C library, roc-send command line tool, or module-roc-sink
• as a receiver, you can use either roc_receiver from the C library, roc-recv command line tool, or module-roc-sink-input

Troubleshooting

First, run PulseAudio server in verbose mode, both on sending and receiving sides:

pulseaudio -vvv

Among other things, you should find some messages from Roc sink and sink-input there, which may give some idea about what's going wrong.

Second, you can try to replace sender, receiver, or both with Roc command line tools to determine whether the issue is specific to PulseAudio modules or not.

Authors

See here.

License

PulseAudio modules are licensed under LGPL 2.1.

For details on Roc Toolkit licensing, see here.