Media Recorder

Record audio or video in the browser and get a file you can upload. No dependencies, no network, no API keys.

Nodes

Record Media (nodegx.mediarecorder)

Port	Direction	Type	Description
Mode	input	enum	Audio or Video. Chooses the getUserMedia constraints and the container. Default Audio.
Media Stream	input	mediastream	Optional. Record this stream instead of opening a new one — wire the Web Camera node's Media Stream output here and the browser is not asked for permission twice.
Mime Type	input	string	Optional container override, e.g. video/webm;codecs=vp8,opus. Ignored if the browser does not support it. Leave empty to let the node pick.
Max Duration	input	number	Seconds. Above 0, the recording stops itself at this length. 0 (default) means no limit.
File Name	input	string	Optional name for the produced file. Defaults to audio-<timestamp>.webm / video-<timestamp>.webm.
Start	input	signal	Begin recording. Ignored while already recording.
Stop	input	signal	Finish the recording and publish the file.
Cancel	input	signal	Stop and discard — no file, no Stopped, and the device is released.
Started	output	signal	Recording has begun (permission was granted).
Stopped	output	signal	A recording finished and File, Blob URL, Size and Duration are set.
Permission Denied	output	signal	The user refused, or the page is not in a secure context.
Device Busy	output	signal	The microphone or camera is held by another application or tab.
No Device	output	signal	Nothing matching the requested constraints exists.
Failure	output	signal	Fires for every failure, including the three named above, so one catch-all wire is enough. It fires before the specific signal, so a graph that wires both sees the specific one land last.
Recording	output	boolean	True between Started and Stopped.
File	output	object	A File ready to hand to Noodl.Files.upload.
Blob URL	output	string	An object URL for the recording — wire it into a Video node's Source.
Recorded Mime Type	output	string	The container the browser actually used, which may not be the one requested.
Duration	output	number	Length in seconds, to one decimal.
Size	output	number	Size of the recording in bytes.
Error	output	string	Human-readable failure message; empty while things are fine.

What it does that a hand-rolled recorder usually does not

• No base64 round trip. The finished Blob becomes a File directly. Going via FileReader.readAsDataURL and back through atob — the usual recipe — holds two extra copies of the recording in memory as JavaScript strings, each about 1.37× the byte size, on the main thread.
• Tracks are actually released. MediaRecorder.stop() stops the recorder, not the stream. This node stops every track it opened on Stop, on Cancel, and when the node is unmounted — so navigating away mid-recording does not leave the camera light on.
• Tracks it does not own are never stopped. A stream arriving on Media Stream belongs to whoever created it; stopping those would black out a Web Camera preview that is still on screen.
• A Cancel during the permission prompt is handled. If the user answers after the node has been cancelled or unmounted, the arriving stream is stopped immediately rather than staying live with nothing holding a reference to it.
• It survives a backgrounded tab. Recording starts with a one-second timeslice, so chunks are flushed as they are produced rather than held in a single buffer, and the duration is measured from the wall clock — a backgrounded tab throttles timers, and a counted interval under-reports.

Two things the drive found

Both were fixed here rather than written down as caveats, and both are the kind of thing only a running browser shows:

• Failure fires before the specific signal, not after. Wiring Failure and Permission Denied to two branches of the same States node is the obvious thing to do, and with the specific signal first the generic one landed last and overwrote it — a refused prompt reported "Failed" and the "Denied" branch was dead on arrival.
• A hidden group is not an unmounted node. Setting a parent Group's Mounted to false removes the component from the page and leaves its non-visual nodes alive and recording. Only a route change deletes the node scope, which is what releases the device. If you need to stop a recording when a section is hidden, wire Cancel — do not rely on hiding it.

Notes

• getUserMedia needs a secure context: https, or localhost. On plain http the node fires Failure with an explanatory Error rather than hanging.
• Browsers gate the permission prompt behind a user gesture — wire Start from a Button's Click, as the bundled Media Recorder Demo component does.
• Container support varies. The node probes MediaRecorder.isTypeSupported and falls back through webm → ogg → mp4; Recorded Mime Type reports what was actually used, so use that (not your requested value) when naming the upload.
• NodeGX has no dedicated Audio node, so the demo plays audio back through a Video node with Controls on. That works — <video> plays an audio-only file — and it keeps the demo free of any other module.
• This module sits beside web-camera, not inside it, and deliberately. Web Camera hands you a live stream to show; this hands you a file to keep, and it also covers audio, which Web Camera cannot do at all. The measurements behind that decision are in COM-005 §4b.