punktfunk/docs-site/content/docs/stats.md

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Understanding the Stats Overlay	What every number in the Punktfunk stats HUD means, and how to compare them fairly with Moonlight/Sunshine.

Every Punktfunk client has an in-stream stats overlay. All clients use the same vocabulary and the same four measurement points, so a stage name on your phone means what the same name means on your desktop.

Two platforms differ in the math: on iOS and tvOS the headline is floor-shaved. The fixed depth of Apple's present pipeline — roughly two refresh intervals, which no client can pace under — is excluded from it, and the Detailed tier prints the excluded term on its own line as os present +X.X excluded (display pipeline minimum). Add that floor back before holding an iPhone, iPad or Apple TV's capture→on-glass next to a macOS, Linux, Windows or Android one. (The macOS client shaves nothing: it presents straight to the display, with no such pipeline depth to measure, so its numbers are raw.)

The four measurement points

Every latency figure is the time between two of these four points in a video frame's life:

1. capture — the host grabs the frame from the (virtual) display. Stamped on the host's clock and carried with the frame.
2. received — your client has fully received and reassembled the frame from the network (after any FEC recovery), before decoding.
3. decoded — the video decoder has produced the picture.
4. displayed — the picture is handed to the screen (as close to "photons" as the platform lets us measure).

Detail levels

The overlay has four levels — Off → Compact → Normal → Detailed — that you cycle live in-stream:

Platform	Cycle with
Linux · Windows · Steam Deck	Ctrl+Alt+Shift+S
macOS / iPad (pointer or trackpad)	⌃⌥⇧S or a three-finger tap
Android · iPhone	a three-finger tap

Ctrl+Alt+Shift+S is one of a small set of shortcuts a stream reserves; the others — release captured input, switch mouse mode, disconnect, mute the microphone — are in Getting your input back.

Compact is a one-line pill (fps · end-to-end ms · Mb/s, plus a loss flag when frames are being lost). Normal adds the stream line and the p50/p95 headline. Detailed adds the per-stage breakdown everywhere; on Linux/Windows it also adds the encoder's target bitrate, the decode path, an HDR tag and a chroma tag, on Android the decoder plus the full codec/bit-depth/colour line, and on iOS/tvOS the excluded OS present floor. You can also set the level a stream starts at in each client's Settings. The examples below are the Detailed view.

The overlay follows your display's scaling, so it should already be readable. To nudge it, set PUNKTFUNK_OSD_SCALE in the client's environment (0.5×–4×) — see Configuration → Client-side.

Reading the overlay

Every client reports the same measurements, but each family lays them out a little differently. Linux · Windows · Steam Deck:

1920×1080@120 · 120 fps · 24.3 Mb/s · target 30 Mb/s (auto) · vulkan · HDR
e2e 14.2/19.8 ms (p50/p95) · host 3.1 · net 6.7 · decode 2.1 · display 2.3 ms
host: queue 0.6 · encode 1.8 · xfer 0.2 · pace 0.5 ms
lost 3 (2.4%)

Android:

1920×1080@120   120 fps   24.3 Mb/s
c2.qti.hevc.decoder · low-latency
HEVC · 10-bit · HDR (BT.2020 PQ) · 4:2:0
end-to-end 14.2 ms p50 · 19.8 p95 · capture→displayed
= host 3.1 + network 6.7 + decode 2.1 + display 2.3
lost 3 (2.4%) · skipped 1 · FEC 12

iOS · tvOS (headline and display both floor-shaved, so they still add up — the raw end-to-end here is 30.7 ms, the 16.7 ms floor of a 120 Hz screen included). macOS lays the same lines out, but with raw numbers and no os present line:

1920×1080@120  120 fps  24.3 Mb/s
end-to-end 14.0 ms p50 · 19.6 p95 · capture→on-glass
= host 3.1 + network 6.7 + decode 2.1 + display 2.1
os present +16.7 excluded (display pipeline minimum)
lost 3 (2.4%)

• Line 1 — the stream. Resolution@refresh, frames received per second, and the received video bitrate (goodput — FEC overhead not counted). Linux/Windows follow the measured rate with target N Mb/s — what the host's encoder is currently allowed to produce — so a quiet desktop under a large grant (measured far below target) reads differently from an encoder pinned at its cap (measured hugging the target). (auto) means the Automatic bitrate controller owns the target and moves it with network conditions; no target at all means an older host that doesn't report one. Then the decode path, an HDR tag (HDR, or HDR→SDR when a PQ stream is tone-mapped onto an SDR screen), and — when you asked for full chroma — the resolved chroma: 4:4:4 when the host granted it, 4:4:4→4:2:0 when it couldn't. Android puts its decoder and the negotiated codec, bit depth, colour and chroma on rows of their own underneath; the Apple clients don't report a codec at all. If the session resolved to a settings profile, its name closes this line. On Android a ⚠ panel NN Hz warning joins it whenever the device's panel is refreshing below the stream's rate — the tell for a phone or TV governor that ignored the requested mode, which otherwise reads as inexplicable judder plus a refresh of extra latency.

• Line 2 — the headline. end-to-end (e2e on Linux/Windows) is the directly measured time from host capture to the endpoint named at the end of the line — capture→on-glass or capture→displayed. Linux/Windows don't spell the endpoint out, because their presenter always measures to the present instant. p50 = the typical frame (median), p95 = the slow outliers. This is the one number that summarizes your stream.

• Line 3 — where the time goes. The first four stages tile the end-to-end interval — each starts where the previous one ends, so they add up to the headline. The two extra terms under them are not extra time: one is excluded from the total, the other sits inside a stage that's already counted.

  • host — capture → sent: the host's own share (capture read, encode, error coding, the paced send), reported by the host itself once per frame.
  • network (net on Linux/Windows) — sent → received: the network flight plus reassembly on your device.
  • decode — received → decoded, on your device.
  • display — decoded → displayed: waiting for the right screen refresh, rendering, and vsync.
  • os present (iOS and tvOS) — the fixed depth of the OS present pipeline, which is excluded from both the headline and display and printed here so you can add it back.
  • client queue (Apple only) — how long a received frame waited before the decoder pulled it. It's the front part of decode, not time on top of it. Hidden below 2 ms; a value that persists is a standing receive backlog on the client.
  • display X (pace A + latch B) and presents N (Android only) — when the timeline presenter is running it splits display in two: pace is the wait it deliberately holds the frame for its target refresh, latch is SurfaceFlinger picking it up and scanning it out. presents counts the frames confirmed on glass this second — well below fps means the presenter is dropping or serializing frames; an fps shortfall with presents keeping up is upstream of the client.

  Against an older host that doesn't report its share yet, the first two terms merge into a single host+network number (host+net on Linux/Windows) — same total, one split fewer. On Linux/Windows, Detailed adds one further line — host: queue … · encode … · xfer … · pace … — splitting the host's own share into its stages, when the host reports them.

  (Stage values are per-stage medians, so they sum only approximately to the headline median — percentiles aren't perfectly additive. The headline is measured directly, never computed as a sum.)

• Line 4 — reliability (only shown when something is nonzero). lost = frames the network dropped beyond FEC's ability to recover — every client reports it. skipped (frames your client chose not to display because a newer one had already arrived) and FEC (packet shards the error correction recovered this second — loss you didn't feel) are reported by the Android client only; the other clients show lost alone.

All values refresh once per second over the last second of frames.

Clocks, and the (same-host clock) tag

end-to-end and host+network span two machines, so they need the two clocks to agree: at connect, the client runs an NTP-style handshake with the host and corrects for the measured clock offset. If that handshake wasn't possible, the overlay appends (same-host clock) — the numbers are then only trustworthy when client and host run on the same machine. decode and display are single-machine measurements and are always exact.

What each platform can measure

Not every platform exposes a true "displayed" instant, so the point the headline stops at differs by client — and the clients that have a choice name it on the line rather than pretending:

client	headline	why
Windows, Linux	capture→on-glass	present instant available (measured right after the Vulkan swapchain present); published raw
macOS (Metal presenter)	capture→on-glass	present instant available (the system's on-glass time for the flip); published raw
iOS/tvOS (Metal presenter)	capture→on-glass	present instant available, but the OS present floor is excluded from the number and printed separately as os present +X.X excluded
Android	capture→displayed	MediaCodec's per-frame render callback reports SurfaceFlinger's render timestamp; on the rare window where no callback is delivered (the platform may drop them under load) the HUD falls back to capture→decoded
macOS/iOS fallback presenter	capture→received	the system video layer hides decode and present timing entirely

A shorter chain means the number is smaller because it measures less — check the endpoint before comparing two devices, and add the excluded os present floor back to an iOS or tvOS client's headline before holding it next to another platform's.

Comparing with Moonlight / Sunshine

Moonlight's overlay and Punktfunk's measure different slices of the pipeline, and the single biggest difference is:

Moonlight has no end-to-end number. Its overlay shows separate client-side segments (decode time, queue delay, render time) and — on Sunshine hosts — a host-side number. Nothing in Moonlight measures capture-to-glass, and nothing measures the network flight of video frames. Punktfunk's end-to-end line has no Moonlight counterpart — never compare it against any single Moonlight line.

To compare fairly, reconstruct an approximate end-to-end from Moonlight's lines:

Moonlight ≈ host processing latency (avg)
          + ½ × average network latency
          + average decoding time
          + average frame queue delay
          + average rendering time

…and compare that against Punktfunk's end-to-end. (It's still approximate: Moonlight's segments are averages over a slightly different window, and the ½·RTT term stands in for a one-way frame flight that Moonlight doesn't measure.)

Line-by-line matrix

Moonlight overlay line	What it actually measures	Punktfunk equivalent	Comparable?
Video stream: WxH FPS	Received plus inferred-lost frames/s (host-rate estimate from frame sequence gaps)	fps (line 1)	≈ equal when loss is near zero; Punktfunk counts received frames only
Incoming frame rate from network	Frames reassembled from the network per second	fps (line 1)	Yes — direct
Decoding frame rate (desktop only)	Frames leaving the decoder per second	not shown separately (equals fps unless the decoder is falling behind)	—
Rendering frame rate (desktop only)	Frames actually presented per second	fps minus skipped (Android only)	Approximately
Host processing latency min/max/avg (Sunshine hosts)	Host capture → just-before-send, reported by Sunshine per frame	host (line 3) — the host reports capture→fully-sent per frame the same way	Yes — direct (Punktfunk's includes the paced send itself, Sunshine's stops just before it; avg vs p50)
Frames dropped by your network connection	Frame-sequence gaps ÷ total frames	lost (line 4)	Yes — direct
Frames dropped due to network jitter	Decoded frames the client's pacer chose to drop ÷ decoded frames	skipped (line 4, Android only)	Approximately (both are client-side pacing decisions, despite Moonlight's name)
Average network latency	The control connection's round-trip time (ENet RTT + variance) — not video frame latency	network (line 3) is the closest concept, but it's the actual one-way frame path (flight + reassembly), not an RTT	No direct comparison. Roughly, Punktfunk's network ≈ ½ × an idle RTT plus serialization time of the frame
Average decoding time	Mean time from decoder enqueue to picture out	decode (p50)	Yes (mean vs median; both include decoder queueing)
Average frame queue delay	Mean time a decoded frame waits for its vsync slot	inside display	Sum the two Moonlight lines →
Average rendering time (incl. V-sync latency)	Mean duration of the present call	inside display	…and compare against Punktfunk's display
(no equivalent)	—	end-to-end — true capture→glass, clock-skew-corrected across machines	Punktfunk only
(no equivalent)	—	FEC recovered shards (loss absorbed invisibly; Android only)	Punktfunk only

Other differences worth knowing when squinting at both overlays side by side:

• Averages vs percentiles. Moonlight's time values are means; Punktfunk shows medians (p50) with a p95 for the headline. Under jitter, a mean sits above the median — Moonlight's numbers read slightly "worse" than an equivalent p50.
• Windows. Both refresh about once per second; Moonlight over a ~1–2 s sliding window, Punktfunk over the last full second.
• Host frame rate. Moonlight's headline FPS estimates what the host produced (received + lost). Punktfunk shows what your client actually received, and reports loss separately.

Recording a capture for a bug report

The overlay only ever shows the last second. To capture a whole run, use the host's own recorder — the Performance page in the web console:

1. Press Start capture. Sampling happens at the host's existing aggregation boundary (about every 1–2 s), so arming it costs the stream nothing.
2. Reproduce the problem. The live graphs fill in as it runs.
3. Press Stop & save. The recording appears in the list below, and survives a host restart.

A recording carries per-stage p50/p99 pipeline latency, new frames/s versus re-encoded holds/s (source starvation), the attempted wire bitrate against the target, and frame/packet/send drops plus FEC recoveries. Its header names the encoder backend and the GPU that produced it — without those, a stage split can't be read at all.

Download saves it as a .json file you can attach to a report; Delete removes it. On disk they live on the host in ~/.config/punktfunk/captures/ (%ProgramData%\punktfunk\captures\ on Windows) until you delete them.