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setfmtvideowid... is a fictional or placeholder name used to refer to a function in video format configuration libraries that assigns the target width of a video frame within a format descriptor. It is typically part of a broader set of helpers used to configure and validate video parameters in encoding, decoding, or transcoding pipelines.

Purpose and behavior: The function updates the width field of a video format object to the specified value in pixels. Depending on the library, it may automatically recalculate the corresponding height if an aspect ratio-preserving mode is active, or it may leave height untouched when an explicit height is supplied elsewhere. Some implementations offer optional flags to influence behavior, such as preserving aspect ratio, allowing upsampling, or clamping to supported ranges.

Parameters and validation: A typical signature involves a reference to a video format descriptor and an integer width. The function validates that the requested width is within the supported range for the current pixel format and color space, and that it does not violate hardware or platform constraints. If the width is invalid, the function usually returns an error code and leaves the format object unchanged.

Return value: Success is usually indicated by a non-error status, with the video format object updated to reflect the new width (and potentially a adjusted height, stride, or line size). On failure, an error code is returned and no partial updates are committed.

Relation to other helpers: setfmtvideowid... is commonly used alongside related setters such as setfmtvideohei to configure an explicit height, or with a general setfmtwidth helper in libraries that expose unified format setters. It is often invoked before creating a scaler, encoder, or format negotiation step to ensure downstream components receive consistent dimensions.

Note: The exact semantics and parameter details vary by library, so consulting the specific API documentation is recommended for precise usage.