Introduction

Nageru is a live video mixer, based around the standard M/E workflow.

Features:

  • High performance on modest hardware (720p60 with two input streams on my Thinkpad X240 [1]); almost all pixel processing is done on the GPU.
  • High output quality; Lanczos3 scaling, subpixel precision everywhere, white balance adjustment, mix of 16- and 32-bit floating point for intermediate calculations, dithered output, optional 10-bit input and output support.
  • Proper sound support: Syncing of multiple unrelated sources through high-quality resampling, multichannel mixing with separate effects per-bus, cue out for headphones, dynamic range compression, three-band graphical EQ (pluss a fixed low-cut), level meters conforming to EBU R128, automation via MIDI controllers.
  • Theme engine encapsulating the design demands of each individual event; Lua code is responsible for setting up the pixel processing pipelines, running transitions etc., so that the visual look is consistent between operators.
  • Comprehensive monitoring through Prometheus metrics.
[1]For reference, that is: Core i7 4600U (dualcore 2.10GHz, clocks down to 800 MHz after 30 seconds due to thermal constraints), Intel HD Graphics 4400 (ie., without the extra L4 cache from Iris Pro), single-channel DDR3 RAM (so 12.8 GB/sec theoretical memory bandwidth, shared between CPU and GPU).

Compiling

The preferred way of getting Nageru is usually from your Linux distribution of choice, but you can of course also compile it yourself (which will also usually give you a newer version). It currently need:

  • Movit, my GPU-based video filter library (https://movit.sesse.net). You will need at least version 1.5.2.

  • Qt 5.5 or newer for the GUI.

  • QCustomPlot for the histogram display in the frame analyzer.

  • libmicrohttpd for the embedded web server.

  • x264 for encoding high-quality video suitable for streaming to end users.

  • ffmpeg for muxing, and for encoding audio. You will need at least version 3.1.

  • Working OpenGL; Movit works with almost any modern OpenGL implementation. Nageru has been tested with Intel on Mesa (you want 11.2 or newer, due to critical stability bugfixes), and with NVIDIA’s proprietary drivers. The status of AMD’s proprietary drivers is currently unknown.

  • libzita-resampler, for resampling sound sources so that they are in sync between sources, and also for oversampling for the peak meter.

  • LuaJIT, for driving the theme engine.

  • libpci, for printing friendly PCI device names in an error message.

  • Optional: CEF (Chromium Embedded Framework), for HTML graphics. If you build without CEF, the HTMLInput class will not be available from the theme. You can get binary downloads of CEF from

    Simply download the right build for your platform (the “minimal” build is fine) and add CEF_DIR=<path>/cef_binary_X.XXXX.XXXX.XXXXXXXX_linux64 on the make command line (substituting X with the real version as required).

If on Debian stretch or something similar, you can install everything you need with:

apt install qtbase5-dev libqt5opengl5-dev qt5-default libqcustomplot-dev
pkg-config libmicrohttpd-dev libusb-1.0-0-dev libluajit-5.1-dev libzita-resampler-dev libva-dev libavcodec-dev libavformat-dev libswscale-dev libavresample-dev libmovit-dev libegl1-mesa-dev libasound2-dev libx264-dev libbmusb-dev protobuf-compiler libprotobuf-dev libpci-dev

Exceptions as of February 2018:

  • You will need Movit from unstable; stretch only has 1.4.0.
  • You will need bmusb from unstable; stretch only has 0.5.4.
  • Debian does not carry CEF (but it is optional).

The patches/ directory contains a patch that helps zita-resampler performance. It is meant for upstream, but was not in at the time Nageru was released. It is taken to be by Steinar H. Gunderson <sesse@google.com> (ie., my ex-work email), and under the same license as zita-resampler itself.

To start it, just hook up your equipment, type “make” and then “./nageru”.