A simple shadowplay/relive/OBS replay buffer-esque setup for wlroots compositors (and maybe others?) written in POSIX shell

• wl-screenrec: https://github.com/russelltg/wl-screenrec/
• pactl
• a VAAPI-capable GPU and /dev/dri/renderD* node
• any POSIX-capable shell
• notify-send and a corresponding notification daemon such as fnott if you want a desktop notification when a clip is dumped

• Put the scripts in $PATH somewhere. Generally, on Linux, a good location is /usr/local/bin.

• Start the replay buffer by running replay-capture (i have mine running from runit as a user service)
• Dump the current clip by running replay-dump [output.mkv]

If no output option is given, replay-dump writes to replay-YYYYMMDD-HHMMSS.mkv in the current directory and prints the filename.

If you would like to specify a specific output location, such as to put replay-dump on a keybind, an example could be replay-dump /mnt/hdd/clips/replay-$(date +%Y%m%d-%H%M%S).mkv.

replay-capture is to be run more or less as a daemon and is agnostic as to what starts it, so one could use a service manager like runit or just start it from their window manager.

All configuration is via environment variables. Both scripts read the same REPLAY_BUFDIR so they can find each other- the rest are read by replay-capture only.

• REPLAY_BUFDIR - Directory used for the lock, pidfile, and pending clip, defaults to $XDG_RUNTIME_DIR/replay-buffer, or /tmp/replay-buffer if XDG_RUNTIME_DIR is unset
• REPLAY_WINDOW_SECS - How many seconds of history to keep buffered, defaults to 150 (2.5 minutes)
• REPLAY_TAIL_SECS - How many extra seconds to keep recording after a dump is triggered before the recorder is stopped, defaults to 0, meaning the clip ends at the moment replay-dump was invoked
• REPLAY_FRAMERATE - Max framerate passed to wl-screenrec, defaults to 60
• REPLAY_OUTPUT - Wayland output to record, defaults to DP-3. Use wlr-randr or your compositors output list, swaymsg -t get_outputs for example, to find the right name
• REPLAY_DEVICE - DRI render node passed to wl-screenrec --dri-device, defaults to /dev/dri/renderD128

• REPLAY_FFMPEG_ENCODER - ffmpeg encoder name, defaults to hevc_vaapi
• REPLAY_RC_MODE - Rate-control mode passed through to the VAAPI encoder, defaults to CQP
• REPLAY_QP - Quantization parameter for CQP mode, defaults to 22, lower is higher quality and larger files
• REPLAY_ENCODE_PIXFMT - Pixel format passed to wl-screenrec --encode-pixfmt, defaults to vuyx

replay-capture creates a null sink, loopbacks the mic and the desktop monitor source into it, then points wl-screenrec at that sinks monitor. This is so the recorded audio contains both your voice and game/desktop audio mixed together.

• REPLAY_MIC_SOURCE - PipeWire/PulseAudio source name for the microphone, this does not have a default, look for your microphone in pactl list sources short to apply to this envvar. Example value: alsa_input.usb-0c76_USB_PnP_Audio_Device-00.mono-fallback
• REPLAY_DESKTOP_SOURCE - Monitor source of the sink your desktop audio plays out of, this does not have a default, look for a source name ending in .monitor in pactl list sources short to apply to this envvar. Example value: alsa_output.usb-GuangZhou_FiiO_Electronics_Co._Ltd_FiiO_K5_Pro-00.analog-stereo.monitor
• REPLAY_DESKTOP_VOLUME - Raw PulseAudio volume value applied to the desktop loopbacks sink-input, defaults to 23253. 65536 is 100%, this exists because desktop audio is usually too loud relative to the mic in the final mix. If you don't care about audio, the simplest path is to comment out the setup_audio call and the --audio / --audio-device flags in replay-capture

• $REPLAY_BUFDIR/lock - Directory created with mkdir as a mutex against multiple replay-capture instances
• $REPLAY_BUFDIR/pid - PID of the running replay-capture
• $REPLAY_BUFDIR/pending.mkv - Output file wl-screenrec writes into, exists for the duration of one capture cycle
• $REPLAY_BUFDIR/pending.done.mkv - Renamed-from-pending.mkv once the recorder has stopped. replay-dump polls for this file as its "flush complete" signal, then renames it to the user-requested output path