gpuDetect.ts

import { spawn } from 'node:child_process';
import { existsSync } from 'node:fs';
import { access } from 'node:fs/promises';

export type GpuBackend = 'cpu' | 'vaapi' | 'nvenc';

export type GpuEncodeConfig = {
  backend: GpuBackend;
  /** Appended to Encore profile base name, e.g. vmp-720p-audio-gpu-vaapi */
  profileSuffix: '' | '-gpu-vaapi' | '-gpu-nvenc';
  vaapiDevice: string;
};

const VAAPI_DEVICE = (process.env.VAAPI_DEVICE || '/dev/dri/renderD128').trim();
const FORCE_GPU = (process.env.VMP_GPU_BACKEND || 'auto').trim().toLowerCase();

let cached: GpuEncodeConfig | null = null;

function runQuick(cmd: string, args: string[]): Promise<boolean> {
  return new Promise((resolve) => {
    const child = spawn(cmd, args, { stdio: 'ignore' });
    const timeout = setTimeout(() => {
      child.kill('SIGKILL');
      resolve(false);
    }, 10_000);
    child.on('error', () => {
      clearTimeout(timeout);
      resolve(false);
    });
    child.on('close', (code) => {
      clearTimeout(timeout);
      resolve(code === 0);
    });
  });
}

async function canUseVaapi(): Promise<boolean> {
  if (!existsSync(VAAPI_DEVICE)) return false;
  try {
    await access(VAAPI_DEVICE);
  } catch {
    return false;
  }
  return runQuick('ffmpeg', [
    '-hide_banner',
    '-init_hw_device',
    `vaapi=va:${VAAPI_DEVICE}`,
    '-f',
    'lavfi',
    '-i',
    'testsrc2=size=64x64:rate=1',
    '-t',
    '0.1',
    '-c:v',
    'h264_vaapi',
    '-f',
    'null',
    '-',
  ]);
}

async function canUseNvenc(): Promise<boolean> {
  return runQuick('ffmpeg', [
    '-hide_banner',
    '-f',
    'lavfi',
    '-i',
    'testsrc2=size=64x64:rate=1',
    '-t',
    '0.1',
    '-c:v',
    'h264_nvenc',
    '-f',
    'null',
    '-',
  ]);
}

export async function detectGpuEncodeConfig(): Promise<GpuEncodeConfig> {
  if (cached) return cached;

  if (FORCE_GPU === 'cpu' || FORCE_GPU === 'none') {
    cached = { backend: 'cpu', profileSuffix: '', vaapiDevice: VAAPI_DEVICE };
    return cached;
  }
  if (FORCE_GPU === 'vaapi') {
    cached = { backend: 'vaapi', profileSuffix: '-gpu-vaapi', vaapiDevice: VAAPI_DEVICE };
    return cached;
  }
  if (FORCE_GPU === 'nvenc' || FORCE_GPU === 'nvidia') {
    cached = { backend: 'nvenc', profileSuffix: '-gpu-nvenc', vaapiDevice: VAAPI_DEVICE };
    return cached;
  }

  if (await canUseNvenc()) {
    cached = { backend: 'nvenc', profileSuffix: '-gpu-nvenc', vaapiDevice: VAAPI_DEVICE };
    return cached;
  }
  if (await canUseVaapi()) {
    cached = { backend: 'vaapi', profileSuffix: '-gpu-vaapi', vaapiDevice: VAAPI_DEVICE };
    return cached;
  }

  cached = { backend: 'cpu', profileSuffix: '', vaapiDevice: VAAPI_DEVICE };
  return cached;
}

export function resolveEncoreProfileBase(base: string, profileSuffix: string): string {
  if (!profileSuffix) return base;
  const withGpu = `${base}${profileSuffix}`;
  return withGpu;
}