aidio-description/dist/server/services/muxer.js

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.muxAudioDescription = muxAudioDescription;
exports.muxMixedAudioDescription = muxMixedAudioDescription;
const child_process_1 = require("child_process");
const path_1 = __importDefault(require("path"));
const fs_1 = __importDefault(require("fs"));
function muxAudioDescription(videoPath, audioPath, outputPath) {
    if (!fs_1.default.existsSync(videoPath)) {
        throw new Error(`mux: video not found: ${videoPath}`);
    }
    if (!fs_1.default.existsSync(audioPath)) {
        throw new Error(`mux: audio not found: ${audioPath}`);
    }
    fs_1.default.mkdirSync(path_1.default.dirname(outputPath), { recursive: true });
    // Argv form — no shell, no quoting issues, and -y is a global option (placed
    // up front, not after the output). Stderr is captured so failures aren't
    // silent.
    const args = [
        '-y',
        '-v', 'error',
        '-i', videoPath,
        '-i', audioPath,
        '-map', '0:v',
        '-map', '0:a?',
        '-map', '1:a',
        '-c:v', 'copy',
        '-c:a', 'copy',
        '-metadata:s:a:1', 'title=Audio Description',
        '-disposition:a:1', 'visual_impaired',
        outputPath,
    ];
    const result = (0, child_process_1.spawnSync)('ffmpeg', args, { shell: false, encoding: 'utf-8' });
    if (result.error) {
        throw new Error(`mux: ffmpeg failed to start: ${result.error.message}`);
    }
    if (result.status !== 0) {
        const tail = (result.stderr || '').trim().split('\n').slice(-5).join(' | ');
        throw new Error(`mux: ffmpeg exited ${result.status}: ${tail || '(no stderr)'}`);
    }
}
function muxMixedAudioDescription(videoPath, audioPath, outputPath) {
    if (!fs_1.default.existsSync(videoPath)) {
        throw new Error(`mux: video not found: ${videoPath}`);
    }
    if (!fs_1.default.existsSync(audioPath)) {
        throw new Error(`mux: audio not found: ${audioPath}`);
    }
    fs_1.default.mkdirSync(path_1.default.dirname(outputPath), { recursive: true });
    // Sidechain-ducked mix: original audio dips when the AD track is speaking,
    // then both are summed into a single output audio stream. The AD track is
    // already a full-length file that is silent between description segments
    // (built by combineAudioSegments), so asplit gives us one copy to drive the
    // sidechain detector and another to mix in on top.
    const filterGraph = '[1:a]asplit=2[ad_mix][ad_sc];' +
        '[0:a][ad_sc]sidechaincompress=threshold=0.03:ratio=20:attack=5:release=300:level_sc=2[ducked];' +
        '[ducked][ad_mix]amix=inputs=2:duration=first:dropout_transition=0:normalize=0[aout]';
    const args = [
        '-y',
        '-v', 'error',
        '-i', videoPath,
        '-i', audioPath,
        '-filter_complex', filterGraph,
        '-map', '0:v',
        '-map', '[aout]',
        '-c:v', 'copy',
        '-c:a', 'aac',
        '-b:a', '192k',
        outputPath,
    ];
    const result = (0, child_process_1.spawnSync)('ffmpeg', args, { shell: false, encoding: 'utf-8' });
    if (result.error) {
        throw new Error(`mux: ffmpeg failed to start: ${result.error.message}`);
    }
    if (result.status !== 0) {
        const tail = (result.stderr || '').trim().split('\n').slice(-5).join(' | ');
        throw new Error(`mux: ffmpeg exited ${result.status}: ${tail || '(no stderr)'}`);
    }
}
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