Picture quality

Picture quality in Slipstream is mostly a client request. You ask for a mode, a codec, a bitrate, HDR, and (where the client can) full chroma; the host answers in the handshake with what it can actually send. A setting the host cannot honor is usually a quiet downgrade rather than an error. Nothing on this page takes effect mid-stream for codec, HDR, or chroma - reconnect after you change them. Bitrate and Match window behave differently; see Client settings.

This page is the tuning guide. The exhaustive per-setting defaults live in Client settings. Host policy gates (SLIPSTREAM_10BIT, SLIPSTREAM_444, PyroWave caps) are in Configuration. Which GPU and client combinations can actually do 10-bit or 4:4:4 is in the Support matrix.

What decides what you see

Four levers matter for how sharp and how smooth a stream looks. They interact; turning every "quality" switch on at once often makes the picture worse on a real link.

Render scale sits beside resolution: the host renders and encodes at your mode multiplied by 0.5x-4x, and the client resamples to the window. Above 1x supersamples for sharpness at more bandwidth and decode work; below 1x is lighter on both. Caps are per-axis 4096 px for H.264 and 8192 px otherwise. Details: Client settings → Video.

There is no host-side bitrate knob. The client requests a rate; the host clamps it to 500 kbps - 8 Gbps (or uses its Automatic defaults below). Use the client's Test network speed... entry on a host card to measure the link and suggest a value - Configuration → Bitrate.

Codecs in one paragraph

Automatic is a soft preference: the host emits your choice when it can also produce it, otherwise the best codec you both speak, in the order HEVC → AV1 → H.264. PyroWave is never auto-picked - you must choose it explicitly on a client that offers it. Android hides AV1 unless the device has a hardware AV1 decoder; Android never offers PyroWave.

Practical rule of thumb:

• HEVC - the usual pick for both desk work and games. Best quality-per-bit for UI among the hardware codecs Slipstream uses day to day, and the usual path for HDR (Main10).
• AV1 - where both ends encode/decode it in hardware. Often efficient; not a requirement for sharp text.
• H.264 - widest compatibility and the GPU-less software path. Never HDR on the hardware Slipstream targets; pinning H.264 pins the session to SDR.
• PyroWave - wired-LAN only, opt-in, hundreds of Mbps. Ultra-low codec latency and every frame a keyframe. See When you are wired.

Bitrate: Automatic vs an explicit rate

For H.264, HEVC and AV1, Automatic means the host's own default, 20 Mbps, and it turns on two things an explicit rate switches off:

1. Adaptive bitrate - the target can move with network conditions during the session.
2. A short link-capacity probe about two seconds in - it measures what your link really carries and lets the rate climb past 20 Mbps when the path allows.

An explicit rate is fixed for the session (still clamped by the host). The stats overlay shows (auto) on the target when Automatic owns it - Understanding the stats overlay.

When Automatic helps

Leave Automatic on when:

• You move between networks (home Wi-Fi one day, VPN the next) and do not want to retune by hand.
• You are not sure what the link carries - the capacity probe is specifically for "start sane, climb if the wire allows."
• The session is mostly quiet desktop with occasional motion: adaptive bitrate can sit under the grant when the picture is static and spend it when something moves.

Prefer an explicit rate when:

• You already ran Test network speed... and want a fixed, known target.
• You are diagnosing soft text or stutter and need the bitrate to stop moving under your feet.
• You are comparing two settings (codec, HDR, chroma) and want one controlled variable.

PyroWave is the exception

PyroWave has no useful low-rate regime. Its Automatic rate is a fixed per-pixel budget for the negotiated mode (hundreds of Mbps at typical desktop sizes), and both adaptive bitrate and the capacity probe stay off for the whole session. An explicit bitrate is honored if you set one, but under sustained loss the right move is switching back to HEVC, not waiting for Automatic to "settle." Cap an over-ambitious Automatic pin on the host with SLIPSTREAM_PYROWAVE_MAX_MBPS - Configuration.

Chroma: why text goes soft

Hardware codecs usually send 4:2:0 - chroma (colour) at half the resolution of luma (brightness). Fine for photographs and most game frames. Bad for small coloured text, thin UI chrome, and red/blue edges: the colour channel is literally subsampled, so glyphs look soft or fringed even when the bitrate is high.

Full chroma (4:4:4) keeps chroma at full resolution. It costs more bandwidth. It needs HEVC or PyroWave, the host's 4:4:4 policy left on (SLIPSTREAM_444, on by default), a capture path that delivers full chroma, and a GPU that can encode it. If any gate fails, the host says 4:2:0 before your decoder is built.

Honest gates today (do not skip these when diagnosing):

• Only HEVC and PyroWave can carry 4:4:4. AV1 and H.264 sessions stay 4:2:0.
• Only NVENC and PyroWave produce it on the host. AMD (VCN / AMF) and Intel (QSV / VAAPI / Vulkan Video) decline HEVC 4:4:4 - that is a hardware or backend limit, not a missing toggle. See the encoder matrix.
• Android, Decky, and the console home do not advertise 4:4:4. Moonlight / GameStream sessions are always 4:2:0.
• On Detailed stats, asking for full chroma prints 4:4:4 when granted or 4:4:4→4:2:0 when the host could not - Stats.

HDR and picture quality

10-bit HDR is on by default. Off means "never send me 10-bit," and the host then never upgrades. On, the stream goes 10-bit BT.2020 PQ only when the host has HDR content and the encoder can do 10-bit. Full chain: HDR.

HDR is not free picture quality for desk work:

• Office UIs and most SDR panels want HDR off. A PQ stream tone-mapped onto an SDR laptop, or software-decoded HDR without a proper swapchain, looks washed or clipped. Where the client overlays it, look for HDR versus HDR→SDR.
• HDR and 4:4:4 fight each other on HEVC/AV1: the host encodes 4:4:4 at 8 bits, so a session that negotiates both resolves back down to SDR before the stream starts (4:4:4 wins).
• H.264 never does HDR. Linux-hosted PyroWave is SDR today - stay on HEVC or AV1 for HDR.

Use two profiles: Work with HDR off (and 4:4:4 when you can get it), Play with HDR as you like it for games and films.

Recipe: Work (sharp UI and text)

Goal: IDEs, browsers, terminals, and documents that look like a local panel - not a soft video of one. Pair this with Desktop at work (Desktop mouse, clipboard, VPN, Workstation / Hot-desk presets). Picture alone does not fix absolute mouse.

Create a Work settings profile and bind it to the office host:

On a capable path, HEVC + 4:4:4 + HDR off is the sharpest desk-work picture Slipstream offers today. Clients that do not advertise 4:4:4 stay on 4:2:0 - raise bitrate and keep HEVC meanwhile.

Over a VPN, raise bitrate until text stops looking muddy, then stop. If the VPN cannot carry more, drop refresh or resolution before chasing settings the product does not have. Over a wired LAN to the same workstation, you can spend much more - including PyroWave with 4:4:4 when you want maximum chroma sharpness and minimum codec latency (still not a WAN codec).

Recipe: Play (motion and high refresh)

Goal: smooth motion, high refresh when the whole pipeline keeps up, HDR for titles that need it. Pair with Capture mouse and a game-oriented host session (gamescope / library launch as you prefer).

High refresh is not a free lunch. A saturated Wi-Fi hop or an undersized bitrate will stutter before the encoder is the limit. Read the stats overlay: network stage vs decode stage tells you which knob to turn. For shooters and racing on a docked Deck or 2.5GbE+ LAN, see PyroWave below.

Save a Play (or Couch) profile next to Work on the same host so you are not retuning HDR and mouse mode every time you switch jobs - Profiles and links.

Soft text: diagnosis

When the desktop looks soft, work the list in order. Most cases are bitrate or chroma, not a corrupt host.

1. Confirm the negotiated stream. Detailed stats: codec, bit depth, HDR tag, and chroma tag (4:4:4 vs 4:4:4→4:2:0 vs no chroma line). Android prints HEVC · 10-bit · HDR (BT.2020 PQ) · 4:2:0 outright. You are diagnosing what the host sent, not what the settings screen still shows from last week.
2. Bitrate too low for the mode. Raise bitrate, or leave Automatic and let the capacity probe climb. Run Test network speed.... Soft glyphs on a 1080p IDE at 10 Mbps on HEVC are expected; soft glyphs at 50 Mbps on a quiet LAN usually point elsewhere.
3. Chroma (4:2:0). Coloured text and red/blue edges look fringed while grayscale looks acceptable - classic 4:2:0. Enable full chroma when your client advertises it and the host GPU can encode it; otherwise raise bitrate and stay on HEVC. Client support is required; the Android app, Decky client, and console home currently stay on 4:2:0.
4. HDR fighting the panel or chroma. Office UI on an SDR laptop with HDR left on → turn HDR off. Wanted 4:4:4 but left HDR on → session may resolve to SDR; turn HDR off for that Work profile.
5. Wrong resolution / upscale. You asked for a smaller mode than the panel, or the host is pinned to a real monitor and the client scales. Prefer Native / Match window for desk work - Virtual displays.
6. Render scale below 1x. Deliberately softer and cheaper; set Native if you did not mean to.
7. H.264 instead of HEVC. Same bitrate, worse UI. Pin HEVC when the host can encode it.
8. Decoder / presentation path. Software decode of an HDR stream can look washed (no HDR10 swapchain path). Turn client HDR off there - HDR → Per client.

If text is sharp but the pointer fights you, that is mouse mode, not picture quality - Input → Mouse modes.

When you are wired: PyroWave

PyroWave is an opt-in wavelet codec for links that can afford real bandwidth: wired Ethernet, a docked Steam Deck, a 2.5GbE LAN. It runs as Vulkan compute on both ends, every frame a keyframe, encode/decode latency far below the hardware H.26x pipelines. Do not run it over Wi-Fi - that is what HEVC/AV1 are for. It is never selected automatically.

Rough Automatic bitrate ballpark (~1.6 bits per pixel, 4:2:0 SDR):

4:4:4 multiplies by ~1.6; HDR adds ~15 %; both together ~1.9× the 4:2:0 SDR rate. Gigabit Ethernet tops out around 940 Mbps of payload, so big 4K / 4:4:4 / HDR / high-refresh modes want 2.5GbE, 5GbE, or 10GbE. The docs page has an interactive estimator.

Turn-on summary:

1. Host: Linux hosts advertise it in default builds (any GPU vendor via Vulkan import; no special host.env line).
2. Client: set Video codec → PyroWave (wired LAN) on Steam Deck where the decode probe passes. Or SLIPSTREAM_PREFER_PYROWAVE=1 where the UI is hard to reach. Android has no PyroWave decoder.
3. Leave bitrate on Automatic unless you need a lower explicit pin or a host SLIPSTREAM_PYROWAVE_MAX_MBPS cap.

PyroWave carries 4:4:4 on Linux hosts. PyroWave HDR is not available on the Linux host today (session is SDR). For sharp desk work on a wired LAN to an NVIDIA box, PyroWave + 4:4:4 (HDR off) is the latency-and-chroma extreme; for HDR games, stay on HEVC or AV1.

Honest limits

Call these out so expectations stay accurate:

• Full-chroma advertising is client-dependent. AMD and Intel hosts cannot encode HEVC 4:4:4; use NVIDIA NVENC or PyroWave.
• Moonlight stays 4:2:0. Full chroma is native slipstream/1 only (SLIPSTREAM_444 has no effect on GameStream).
• Automatic bitrate starts at 20 Mbps for the hardware codecs, then may climb. It is not a guarantee of "as much as the LAN can take" on every hop; use the speed test when you need a measured suggestion.
• HDR is not "more sharpness." It is a colour/brightness pipeline with real gates and real trade-offs against 4:4:4. Desk work usually wants it off.
• PyroWave is not a WAN / Wi-Fi codec. Hundreds of Mbps, no adaptive low-rate mode. Under loss, switch to HEVC.
• Web console cannot set bitrate or run a speed test yet - client apps can. The console can show what a live session is using - Support matrix.

Cross-links

• Client settings → Video - every default and which clients offer which row
• Configuration → Video quality - SLIPSTREAM_444, SLIPSTREAM_10BIT, SLIPSTREAM_PYROWAVE_MAX_MBPS
• Configuration → Bitrate - speed test; no host bitrate knob
• HDR - four-link chain, codec rules, HDR vs 4:4:4
• PyroWave - wired codec, bitrate table, 4:4:4 and HDR
• Support matrix → Encoders - which GPUs encode 10-bit / 4:4:4
• Desktop at work - Work path (mouse, clipboard, VPN, presets)
• Profiles and links - Work vs Play profiles on one host
• Understanding the stats overlay - (auto), chroma tags, HDR→SDR
• How it works - soft text vs motion-to-photon
• Network & VPN - what LAN vs VPN can realistically carry
• Troubleshooting - stutter, loss, and when bitrate is the wrong lever