---
name: "XvQueryBestSize"
section: "3"
platform: "linux"
package: "libxv"
version: "1.0.13-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/XvQueryBestSize"
---

# XvQueryBestSize(3)

determine the optimum drawable region size

## NAME

XvQueryBestSize - determine the optimum drawable region size

## SYNOPSIS

**#include \<X11/extensions/Xvlib.h\>**

```
int XvQueryBestSize(Display *dpy, XvPort port, Bool motion,
                    unsigned int vw, unsigned int vh,
                    unsigned int dw, unsigned int dh,
                    unsigned int *p_dw, unsigned int *p_dh);
```

## ARGUMENTS

- *dpy*

  Specifies the connection to the X server.

- *port*

  Defines the port associated with the display and adaptor for which the optimum size is to be calculated.

- *motion*

  Specifies *True* if the destination size needs to support full motion, and *False* if the destination size need only support still images.

- *vw,vh*

  Specifies the size of the source video region desired.

- *dw,dh*

  Specifies the size of the destination drawable region desired.

- *p\_dw,p\_dh*

  Pointers to where the closest destination sizes supported by the server are returned.

## DESCRIPTION

Some ports may be able to scale incoming or outgoing video. [**XvQueryBestSize**(3)](/XvQueryBestSize/3.md) returns the size of the closest destination region that is supported by the adaptor.  The returned size is guaranteed to be smaller than the requested size if a smaller size is supported.

## RETURN VALUES

- \[Success\]

  Returned if [**XvQueryBestSize**(3)](/XvQueryBestSize/3.md) completed successfully.

- \[XvBadExtension\]

  Returned if the Xv extension is unavailable.

- \[XvBadAlloc\]

  Returned if [**XvQueryBestSize**(3)](/XvQueryBestSize/3.md) failed to allocate memory to process the request.

## DIAGNOSTICS

- \[XvBadPort\]

  Generated if the requested port does not exist.\