* 音频格式转换工具。

*

* Handles SILK ↔ PCM ↔ WAV ↔ MP3 conversions for QQ Bot voice messaging.

* Prefers ffmpeg when available; falls back to WASM decoders (silk-wasm,

* mpg123-decoder) for environments without native tooling.

* Uses WASM decoders (silk-wasm, mpg123-decoder) and direct QQ-native uploads

* without launching native subprocesses.

*

* Self-contained within engine/ — no framework SDK dependency.

*/

import { execFile } from "node:child_process";

import * as fs from "node:fs";

import * as path from "node:path";

import { formatErrorMessage } from "./format.js";

import { debugLog, debugError, debugWarn } from "./log.js";

import { detectFfmpeg, isWindows } from "./platform.js";

import { normalizeLowercaseStringOrEmpty as normalizeLowercase } from "./string-normalize.js";

type SilkWasm = typeof import("silk-wasm");

/**

* Convert a local audio file to Base64-encoded SILK for QQ API upload.

*

* Attempts conversion via ffmpeg → WASM decoders → null fallback chain.

* Attempts conversion via direct QQ-native upload → WASM decoders → null fallback chain.

*/

export async function audioFileToSilkBase64(

filePath: string,

const targetRate = 24000;

const ffmpegCmd = await detectFfmpeg();

if (ffmpegCmd) {

try {

debugLog(

`[audio-convert] ffmpeg (${ffmpegCmd}): converting ${ext} (${buf.length} bytes) → PCM s16le ${targetRate}Hz`,

);

const pcmBuf = await ffmpegToPCM(ffmpegCmd, filePath, targetRate);

if (pcmBuf.length === 0) {

debugError(`[audio-convert] ffmpeg produced empty PCM output`);

return null;

}

const { silkBuffer } = await pcmToSilk(pcmBuf, targetRate);

debugLog(`[audio-convert] ffmpeg: ${ext} → SILK done (${silkBuffer.length} bytes)`);

return silkBuffer.toString("base64");

} catch (err) {

debugError(`[audio-convert] ffmpeg conversion failed: ${formatErrorMessage(err)}`);

}

}

debugLog(`[audio-convert] fallback: trying WASM decoders for ${ext}`);

if (ext === ".pcm") {

}

}

const installHint = isWindows()

? "Install ffmpeg with choco install ffmpeg, scoop install ffmpeg, or from https://ffmpeg.org"

: process.platform === "darwin"

? "Install ffmpeg with brew install ffmpeg"

: "Install ffmpeg with sudo apt install ffmpeg or sudo yum install ffmpeg";

debugError(`[audio-convert] unsupported format: ${ext} (no ffmpeg available). ${installHint}`);

debugError(

`[audio-convert] unsupported format without native subprocess conversion: ${ext}. Use QQ-native voice formats or WAV/MP3/PCM inputs.`,

);

return null;

}

};

}

/** Use ffmpeg to convert any audio to mono 24 kHz PCM s16le. */

function ffmpegToPCM(

ffmpegCmd: string,

inputPath: string,

sampleRate: number = 24000,

): Promise<Buffer> {

return new Promise((resolve, reject) => {

const args = [

"-i",

inputPath,

"-f",

"s16le",

"-ar",

String(sampleRate),

"-ac",

"1",

"-acodec",

"pcm_s16le",

"-v",

"error",

"pipe:1",

];

execFile(

ffmpegCmd,

args,

{

maxBuffer: 50 * 1024 * 1024,

encoding: "buffer",

...(isWindows() ? { windowsHide: true } : {}),

},

(err, stdout) => {

if (err) {

reject(new Error(`ffmpeg failed: ${err.message}`));

return;

}

resolve(stdout as unknown as Buffer);

},

);

});

}

/** Decode MP3 to PCM via mpg123-decoder WASM (fallback when ffmpeg is unavailable). */

/** Decode MP3 to PCM via mpg123-decoder WASM. */

async function wasmDecodeMp3ToPCM(buf: Buffer, targetRate: number): Promise<Buffer | null> {

try {

const { MPEGDecoder } = await import("mpg123-decoder");

}

}

/** Parse a standard PCM WAV and extract mono 24 kHz PCM data (fallback without ffmpeg). */

/** Parse a standard PCM WAV and extract mono 24 kHz PCM data. */

export function parseWavFallback(buf: Buffer): Buffer | null {

if (buf.length < 44) {

return null;