txproto

A fully scriptable and flexible multimedia streaming/handling program.

Features

• Fully scriptable via Lua
• Fully atomic API
• Every frame is perfect
• Frame-perfect synchronization between video and audio capture
• Custom first-class capture/output code for minimal overhead:
  • Most feature-complete and accurate Pulseaudio implementation, including isolated client capture
  • Zero-copy Wayland capture via the wlr-export-dmabuf-unstable protocol
  • Low-overhead X11 capture via XCB/SHM
  • Wayland capture via the wlr-screencopy-unstable protocol (both software or DMA-BUF frames supported)
• Second-class libavdevice capture/output support
• Headless operation supported
• Optional Vulkan-only GUI via libplacebo, supported window systems:
  • Wayland
• Minimal dependencies (FFmpeg and Lua required, libplacebo and all custom capture code optional)
• Liberally licensed (LGPL v2.1)

Building

Complete list of dependencies:

• FFmpeg (git master currently required)
• libplacebo (git master)
• Lua 5.4

Optional dependencies

• Editline 3.1 (for a command-line interface)
• libpulse (for Pulseaudio capture)
• Wayland (wayland-scanner,client,cursor,protocols,xkbcommon and libdrm, for Wayland capture)

To build, simply do:

meson build

ninja -C build

The resulting binary in ./build/src/txproto is portable and can be ran anywhere.

To simplify building, libplacebo can be built and bundled simultaneously by creating
a subprojects directory and cloning the libplacebo repository
into subprojects/libplacebo. If an unsuitable libplacebo version already exist on the
system, use meson setup --force-fallback-for libplacebo build to force building from
the subprojects directory.

Running

If no scripts are specified, txproto will, by default, shadow the entire screen to allow the user to screenshot a portion of the screen via the mouse.

To run a script: ./build/txproto -s <path to script>. Example scripts can be found in the examples
directory. CLI parameters are described in the section below.
Script syntax is described in the Lua API documentation.

CLI

Argument	Description
-s path	Specify a script to run.
-e string	Specifies a script entry function (default: ‘main’).
-r string	Comma-separated list of system Lua packages to include. Searches the local directory first, then the system directories. Note: for security, io, os and require are not loaded by default.
-V string	Specifies a global logging level (quiet, error, warn, info, verbose, debug, trace). For a single component, the syntax is <component>=<level> . Multiple values can be given if separated via commas.
-L path	Specifies a log file. Warning: always at maximum verbose level, this will get big quickly.
-C	Enable the command-line interface.
-h	Display help (this).
-v	Displays program version info.
trailing arguments	Given to the script as variable arguments to the entrypoint (function main(...) local argument1, argument2, etc = ... end).

Discussions and help

Join #txproto on Libera, or #txproto:pars.ee on Matrix.

Feature policy

New feature	Policy
Custom inputs	Always accepted
Custom outputs	Always accepted
Platform integration	Accepted, via Lua scripts
Custom muxers	Welcome
Custom filters	Unlikely, submit to FFmpeg first
Custom de/encoders	Never, submit any to FFmpeg

Alternatively, for custom inputs, outputs, and muxers, a dynamic linking ABI will be provided to allow for the use of non-free binaries.