@bun-win32/avifil32

Zero-dependency, zero-overhead Win32 Avifil32 bindings for Bun on Windows.

Overview

@bun-win32/avifil32 exposes the avifil32.dll exports using Bun's FFI. It provides a single class, Avifil32, which lazily binds native symbols on first use. You can optionally preload a subset or all symbols up-front via Preload().

The bindings are strongly typed for a smooth DX in TypeScript.

Features

• Bun-first ergonomics on Windows 10/11.
• Direct FFI to avifil32.dll (Video for Windows AVIFile API: open/create .avi files, enumerate and read/write video, audio, MIDI, and text streams, decode frames to DIBs, mux files from streams, and edit streams).
• In-source docs in structs/Avifil32.ts with links to Microsoft Docs.
• Lazy binding on first call; optional eager preload (Avifil32.Preload()).
• No wrapper overhead; calls map 1:1 to native APIs.
• Strongly-typed Win32 aliases (see types/Avifil32.ts).

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/avifil32

Quick Start

import Avifil32, { OpenFileFlags, StreamType } from '@bun-win32/avifil32';

// Optionally bind a subset up-front
Avifil32.Preload(['AVIFileInit', 'AVIFileOpenW', 'AVIFileInfoW', 'AVIFileRelease', 'AVIFileExit']);

Avifil32.AVIFileInit();

// AVIFileOpenW writes the IAVIFile pointer into a caller-allocated buffer
const ppfile = Buffer.alloc(8);
const path = Buffer.from('C:\\\\sample.avi\0', 'utf16le');
const hr = Avifil32.AVIFileOpenW(ppfile.ptr, path.ptr, OpenFileFlags.OF_READ | OpenFileFlags.OF_SHARE_DENY_NONE, null);

if (hr === 0) {
  const pfile = ppfile.readBigUInt64LE(0);

  // AVIFILEINFOW is 172 bytes on x64; dwStreams is at offset 12
  const info = Buffer.alloc(172);
  Avifil32.AVIFileInfoW(pfile, info.ptr, info.byteLength);
  console.log('Streams: %d', info.readUInt32LE(12));

  Avifil32.AVIFileRelease(pfile);
}

Avifil32.AVIFileExit();

[!NOTE] AI agents: see AI.md for the package binding contract and source-navigation guidance. It explains how to use the package without scanning the entire implementation.

Examples

Run the included examples:

# Decode a synthesized .avi and play it back in the terminal with 24-bit ANSI
bun run example/terminal-cinema.ts

# Thorough AVI container diagnostic (pass a path, or a sample is synthesized)
bun run example/avi-inspector.ts [path-to.avi]

Notes

• Either rely on lazy binding or call Avifil32.Preload().
• Windows only. Bun runtime required.
• SAL types & naming: nullability is in the type — Optional<T> (formally optional, SAL _*opt_) and Nullable<T> (plain [in]/[out] the docs say can be NULL), the null sentinel derived from T (null for pointers LP*/P*, 0n for handles/by-value addresses); direction is in the parameter name — _out (_Out_), _in_out (_Inout_), _In_ bare. See AI.md and the repo AGENTS.md.