Record the desktop

humanish keeps screenshots, actions, participant feedback and analysis by default. For continuous playback, opt into a desktop video:

execution:
  desktop:
    recording: { audio: true }

Set audio: false for screen-only video. Omit recording to keep the lightweight snapshot recording. This applies to independent computer-use desktop participants on local Firecracker and E2B; scripted-browser, shared-world and in-process executors do not consume this setting and reject it before execution.

Recording does not enable a camera, speech synthesis or speech recognition. Those remain separate participant media options. With audio enabled, microphone input and speaker output are mixed into one AAC track. audioSources identifies the capture points feeding that mix, not separate retained tracks. The microphone can be silent when speech is not configured. A recorded microphone signal proves what was offered to the browser, not what another person received. Confirm reciprocal delivery from the other participant's evidence.

Capture and playbackCopy Anchor Link

The desktop runs FFmpeg against its X display. MP4 carries H.264 video and optional AAC audio. Recording stops and streams to the run directory before desktop cleanup. Both providers use the same encoding settings and artifact metadata. Video encoding uses the capture input’s microsecond time base, preserving closely spaced captures and their offsets rather than rounding them to the nominal frame interval. Explicit variable-frame-rate output preserves gaps without filling them with duplicate frames across the supported FFmpeg versions. The recording mix disables playback rewinds to avoid the null sink's initial two-second buffer. The local runtime transfers one bounded file over its existing owner connection; E2B uses the SDK's streaming file download. Participant tools cannot request arbitrary files.

Local recording uses the existing optional media runtime archive. This keeps the browser-only download unchanged, but the optional archive also contains speech assets even when speech is disabled. Recording alone does not start Whisper or text-to-speech. E2B's stock desktop already has the recording dependencies; a custom template must provide compatible FFmpeg, X11 and, for audio, PulseAudio tools.

Observer uses the existing study clock to play the selected participant's video. Scrubbing, opening a participant and returning to the grid preserve study time. The grid continues to show lightweight captures; only the selected participant has audible playback. Outside the retained media interval, Observer shows that video is unavailable rather than extending its coverage. Old screenshot-only runs continue to work.

Capture still begins after device and transport startup. An audio track can contain silence before a cold source delivers sound; early dispatch of speech or playback does not itself prove audible capture. Preserve these offsets when reviewing early events. The startup correction does not reconstruct missing frames or audio in existing files. Variable guest execution stalls can still leave frame gaps; the recorded timestamps preserve those gaps. A regularly timestamped video can also show an unchanged screen while the application stalls. Visual/audio event timing depends on source delivery and guest execution; timestamp precision does not guarantee simultaneous delivery. An open issue tracks the remaining investigation.

The file and its measured interval are recorded in streams[].recording and a recording artifact entry. A recorder failure warns and preserves screenshots, actions and feedback; it does not fail an otherwise useful participant. Incomplete but playable media is labeled partial. Forced VM loss may leave no retrievable video. Analysis continues to use the existing screenshot and text evidence; it does not inspect the MP4.

Local evidence and exportsCopy Anchor Link

Video and audio are raw local evidence. policies.redactScreenshots does not redact them, and verification keeps a run with continuous media local_only. The recorder has a 128 MiB per-participant file limit; a retained size-limited recording is partial. Encoding consumes additional CPU, memory and disk, so snapshots remain the default.

humanish export --local-only produces the existing portable HTML with screenshots and text, excludes continuous media and displays that exclusion. Open the original run through humanish watch or humanish observe --all to play its video. Redacted bundle export does not redact video/audio and rejects these runs. There is no new portable video format or automatic audio/video redaction in this feature.