Technical requirements

QJams is a lightweight, natively compiled C application built for real-time audio and video workflows. To ensure optimal performance and lock-free execution, your Linux system should meet the following baseline:


Operating System: A modern 64-bit Linux distribution (glibc 2.38+ recommended). QJams is natively optimized for Arch-based rolling releases, such as CachyOS and Manjaro, running KDE Plasma under Wayland. A universal build is also provided for broad compatibility across standard distributions like Fedora, Debian, and Ubuntu (24.04+).

Audio Subsystem: A functional JACK audio server or a modern PipeWire deployment with the pipewire-jack module enabled.

Hardware Inputs: Any standard V4L2-compatible camera or webcam paired with a class-compliant USB audio interface or hardware modeler (such as the Neural DSP Quad Cortex). QJams supports live hardware hot-plugging; you can safely plug in or power-cycle your gear while the application is running. QJams also works without a cam by displaying a blank video pane.

System Memory (RAM): 8 GB minimum. 16 GB or more is highly recommended for full multi-layer arrangements and longer recording sessions. To guarantee zero-latency execution, the QJams memory gatekeeper enforces a strict 2 GB absolute OS RAM floor to prevent system lockups.

Processor: A 64-bit x86_64 multi-core processor. A dedicated AVX-512 optimized build is provided for modern high-performance CPUs alongside the x86-64-v3 universal build.


Understanding RAM Requirements

Standard audio production environments often recommend 16 GB to 32 GB of RAM to manage large multi-track sessions efficiently. QJams has a unique memory footprint because it is designed for lock-free, zero-latency live performance and simultaneous video recording.

To guarantee audio engine stability, QJams pre-allocates uncompressed 32-bit audio arrays for all 12 multi-track layers the moment you load a file or start a session. Because of this, the length of your session timeline dictates your physical memory requirements.


QJam's 2 GB OS Floor & Atomic Undo Ledger

Instead of a fixed percentage cap, QJams calculates your active physical memory and explicitly reserves a 2 GB absolute floor to keep your Linux desktop running smoothly. The remaining memory is dedicated to your active tracks and the dynamic global Undo Ledger, which can safely hold up to 64 complete transaction states. If a video, backing track, or complex edit demands more memory than what is available above the 2 GB floor, QJams will block the operation with an "Insufficient RAM" warning to protect your system from crashing.


Memory Capabilities & Limitations

Below are the estimated maximum timeline lengths based on your system hardware:


What Will Load Flawlessly: Standard backing tracks and song lengths (3 to 10 minutes) on almost any modern 8 GB machine. Continuous 15-minute live freestyle performances and loop sessions on 16 GB machines.

What Will Not Load: Full-length movies, 2-hour podcasts, or massive concert MKV files on systems with 16 GB or less. Attempting to load files that exceed your specific hardware capacity will trigger a safety rejection. Note: Exact limits depend on your specific system configuration and background applications.


Overview: Unified 12-Track Workflow

QJams utilizes a unified, single-window workflow. It is a 12-track, non-destructive live recording canvas that integrates perfectly synced video directly into the timeline.


Load Media: Select an audio backing track (FLAC, WAV, MP3, etc.) or an existing MKV video by dragging and dropping it into the app, or by using the Load Media button.

Set Levels: Adjust your input gain (e.g., Quad Cortex) and the backing track volume using the post-buffer dashboard spinners.

Lay the Foundation: Hit record to lay down your base rhythm on the first track. The engine captures your playing and your webcam feed simultaneously.

Stack Overdubs: Select the next track row (or press your mapped keyboard shortcut) to seamlessly jump to the next layer and continue building without stopping playback.

Correct & Edit: Click a track's Undo arrow or use Ctrl+Z to instantly wipe an active overdub. The dynamic ledger remembers your edit history so you can undo and redo without fear. Use the track scissors to surgically cut, ripple delete, and fade specific layers.

Save & Export: Save your progress as a .qjams session file to pick up where you left off. When the track is done, click Export to mix the active layers into a master-quality audio file, or mux it perfectly with your video feed into a high-quality MKV file.


Installation & First Launch

QJams is distributed as a standalone, portable AppImage, meaning there are no complex dependencies or system packages to install.