# Best practices

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These recommendations help you ship a polished video experience with the Video SDK for Linux.

## Camera access and selection

On Linux, the SDK captures from cameras exposed through V4L2. On machines with more than one camera, don't assume the default is correct.

-   Confirm at least one camera is present with `getNumberOfCameras` before calling `startVideo`.
-   Let the user choose a camera, or select a known device by ID. For details, see [Camera controls](/docs/video-sdk/linux/video/camera-controls/).

## Manage subscriptions for rendering

You render remote video by subscribing to each user's raw video pipe. On a busy session, subscriptions are the main driver of CPU and bandwidth cost.

-   Subscribe only to the users you are actually displaying. Unsubscribe from a user's pipe as soon as their tile leaves the screen.
-   Match the subscription resolution to the size you render at. Subscribing at a higher resolution than you display wastes decode time.
-   Add and remove subscriptions in response to `onUserJoin` and `onUserLeave`. For details, see [Receive raw data](/docs/video-sdk/linux/raw-data/receive-raw-data/).

## Show video status in your UI

Render each user's video on/off state from their `ZoomVideoSDKVideoStatus`, and update it when [`onUserVideoStatusChanged`](/docs/video-sdk/linux/video/video-events/#user-video-status) fires, so participants can tell who has their camera on.

## Headless and server deployments

Many Linux Video SDK apps run headless, for example a bot or recorder deployed to a cloud host.

-   A headless host usually has no physical camera. To send video without a camera, provide a custom video source rather than calling `startVideo` against hardware. For details, see [Send raw data](/docs/video-sdk/linux/raw-data/send-raw-data/).
-   To process or record remote video, subscribe to each user's raw video pipe and handle the YUV frames directly rather than rendering to a display.

## Manage quality under limited bandwidth

When bandwidth is constrained, set a video quality preference so the SDK trades resolution against frame rate in the way that suits your content. For details, see [Manage video quality](/docs/video-sdk/linux/video/video-quality/).