Video and audio encoding options for nestri-server

nestri-server builds its GStreamer encoding pipeline from the flags described on this page. Video and audio encoding are configured independently. The server selects the best available hardware encoder for the requested codec at startup; you can override the encoder name directly if you need to pin a specific GStreamer element.

Video encoding

Codec selection

--video-codec

string

default:"h264"

Preferred video codec. The server selects the highest-scoring encoder that supports this codec and successfully initialises.Accepted values: h264, h265, av1Environment variable: VIDEO_CODEC

Value	Aliases accepted	Notes
`h264`	`h.264`, `avc`	Default. Widest browser support. 8-bit colour only.
`h265`	`h.265`, `hevc`, `hev1`	Better compression; browser support varies.
`av1`	—	Best efficiency; Chromium-based browsers.

--video-encoder

string

Override the automatic encoder selection with a specific GStreamer element name (e.g. vah264lpenc, nvh265enc, x264enc). The named element must exist in the GStreamer registry.Environment variable: VIDEO_ENCODER

--video-encoder-type

string

default:"hardware"

Constrain encoder selection to hardware or software. When set to hardware, only elements whose GStreamer klass metadata contains /hardware are considered.Environment variable: VIDEO_ENCODER_TYPE

Rate control

--video-rate-control

string

default:"cbr"

Rate control method for the video encoder.Accepted values: cbr, vbr, cqpEnvironment variable: VIDEO_RATE_CONTROL

CBR — Constant Bitrate

Encoder targets exactly --video-bitrate kbps at all times. Produces predictable network utilisation and is the recommended mode for streaming.Uses --video-bitrate as the target; --video-bitrate-max is ignored.

VBR — Variable Bitrate

Encoder targets --video-bitrate kbps but may burst up to --video-bitrate-max kbps on complex scenes. Typically produces better quality than CBR at the same average bitrate.

CQP — Constant Quantization Parameter

Encoder targets a fixed perceptual quality level defined by --video-cqp. Bitrate floats with scene complexity. Not bandwidth-bounded; use only on unconstrained networks.

--video-bitrate

number

default:"6000"

Target video bitrate in kbps. Used by CBR and VBR rate control.Environment variable: VIDEO_BITRATE

--video-bitrate-max

number

default:"8000"

Maximum video bitrate in kbps. Used only by VBR rate control.Environment variable: VIDEO_BITRATE_MAX

--video-cqp

number

default:"26"

Constant Quantization Parameter quality level. Lower values produce higher quality at higher bitrates. Valid range: 1–51. Used only by CQP rate control.Environment variable: VIDEO_CQP

Latency control

--video-latency-control

string

default:"lowest-latency"

Tuning preset applied on top of the selected rate control mode.Accepted values: lowest-latency, highest-qualityEnvironment variable: VIDEO_LATENCY_CONTROL

Value	Description
`lowest-latency`	Sets encoder parameters that minimise encode-to-transmit delay. For NVENC: `preset=p1`, `tune=ultra-low-latency`, `zerolatency=true`. For QSV: `low-latency=true`, `target-usage=7`. For x264enc: `speed-preset=ultrafast`, `tune=zerolatency`.
`highest-quality`	Allows the encoder to use lookahead frames and multi-pass encoding for better visual quality at the cost of added latency. For NVENC: `preset=p7`, `tune=high-quality`, `multi-pass=two-pass`, `spatial-aq=true`, `rc-lookahead=3`.

Keyframe interval

--keyframe-dist-secs

number

default:"1"

Distance between keyframes (I-frames) in seconds. The actual GOP size sent to the encoder is framerate × keyframe-dist-secs. Shorter intervals improve seek and recovery behaviour but increase bitrate.Environment variable: KEYFRAME_DIST_SECS

Bit depth

--video-bit-depth

number

default:"8"

Video bit depth. Accepted values: 8, 10.Environment variable: VIDEO_BIT_DEPTH10-bit output requires all three of the following conditions to be true:

--zero-copy is enabled (DMA-BUF or CUDA memory path)
The video codec is not h264 (H.264 does not support 10-bit)
The selected encoder supports 10-bit output

When 10-bit is active the VA-API/QSV pipeline uses P010_10LE format instead of NV12.

H.264 does not support 10-bit colour. If you set --video-bit-depth 10 with --video-codec h264, the server will use 8-bit regardless.

Audio encoding

nestri-server currently supports Opus as the only audio codec. The opusenc GStreamer element is used by default, with a 10 ms frame size for low latency.

Audio capture

--audio-capture-method

string

default:"pipewire"

Audio capture backend. The selected value determines which GStreamer source element is used.Accepted values: pipewire, pulseaudio, alsaEnvironment variable: AUDIO_CAPTURE_METHOD

Value	GStreamer element	Notes
`pipewire`	`pipewiresrc`	Default. Recommended with WirePlumber session manager.
`pulseaudio`	`pulsesrc`	Use when PipeWire is not available.
`alsa`	`alsasrc`	Direct ALSA access; no sound server required.

Codec and encoder

--audio-codec

string

default:"opus"

Preferred audio codec. Currently only opus is supported.Environment variable: AUDIO_CODEC

--audio-encoder

string

Override the audio encoder GStreamer element name. Defaults to opusenc. Use this if you need a custom or patched encoder element.Environment variable: AUDIO_ENCODER

Audio rate control and bitrate

--audio-rate-control

string

default:"cbr"

Rate control method for the audio encoder. Accepted values: cbr, vbr.Environment variable: AUDIO_RATE_CONTROL

CQP is not supported for audio. Setting cqp for audio rate control will cause the server to exit with an error.

--audio-bitrate

number

default:"128"

Target audio bitrate in kbps. Used by both CBR and VBR rate control.Environment variable: AUDIO_BITRATE

--audio-bitrate-max

number

default:"192"

Maximum audio bitrate in kbps. Used only by VBR rate control.Environment variable: AUDIO_BITRATE_MAX

--audio-latency-control

string

default:"lowest-latency"

Audio latency tuning preset. Accepted values: lowest-latency, highest-quality. The opusenc frame size is always set to 10 ms regardless of this setting.Environment variable: AUDIO_LATENCY_CONTROL

Common configurations

Low-latency game streaming (default)
Higher quality (increased latency)
AV1 with zero-copy

The default settings are optimised for interactive game streaming at 1080p/60 fps:

nestri-server \
  --relay-url wss://relay.example.com \
  --resolution 1920x1080 \
  --framerate 60 \
  --video-codec h264 \
  --video-rate-control cbr \
  --video-bitrate 6000 \
  --video-latency-control lowest-latency \
  --audio-capture-method pipewire \
  --audio-bitrate 128

Raise bitrate and switch to highest-quality latency preset for recordings or slower-paced games:

nestri-server \
  --relay-url wss://relay.example.com \
  --video-codec h265 \
  --video-rate-control vbr \
  --video-bitrate 10000 \
  --video-bitrate-max 15000 \
  --video-latency-control highest-quality \
  --audio-bitrate 192

AV1 encoding via VA-API with zero-copy DMABuf transfer:

nestri-server \
  --relay-url wss://relay.example.com \
  --video-codec av1 \
  --video-rate-control cbr \
  --video-bitrate 4000 \
  --zero-copy

Zero-copy is experimental. Verify it works correctly on your GPU/driver combination before deploying.

Get Started

Self-Hosting

Streaming Server

Integrations

Video and audio encoding options for nestri-server

Video encoding

Codec selection

Rate control

Latency control

Keyframe interval

Bit depth

Audio encoding

Audio capture

Codec and encoder

Audio rate control and bitrate

Common configurations

Build docs developers (and LLMs) love

Get Started

Self-Hosting

Streaming Server

Integrations

Documentation Index

​Video encoding

​Codec selection

​Rate control

​Latency control

​Keyframe interval

​Bit depth

​Audio encoding

​Audio capture

​Codec and encoder

​Audio rate control and bitrate

​Common configurations

Build docs developers (and LLMs) love

Video encoding

Codec selection

Rate control

Latency control

Keyframe interval

Bit depth

Audio encoding

Audio capture

Codec and encoder

Audio rate control and bitrate

Common configurations