126 lines
3.3 KiB
TypeScript
126 lines
3.3 KiB
TypeScript
/**
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* 视频分段时长计算算法
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*
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* 根据目标时长和模型可用的 duration 选项，计算最优分段方案。
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* 供 ScriptPage、GeneratePage、long-video.ts 三处复用。
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*/
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import type { DurationOption } from '../types/video.types';
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/** 分段计划结果 */
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export interface SegmentPlan {
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/** 每段的时长（秒）数组，长度等于段数 */
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segments: number[];
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/** 实际总时长 = sum(segments) */
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actualTotal: number;
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/** 是否为固定时长模型 */
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isFixed: boolean;
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/** 目标时长与实际时长的差值（actualTotal - targetDuration），≥ 0 */
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overflow: number;
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}
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/** 默认兜底时长 */
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const FALLBACK_DURATION = 8;
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/**
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* 计算分段方案
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*
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* 策略：
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* - 固定时长模型（options.length === 1）：
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* segmentCount = ceil(targetDur / fixedDur)
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* actualTotal = segmentCount × fixedDur
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*
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* - 可变时长模型（options.length > 1）：
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* 1. 若 targetDur ≤ maxDur → 单段，选 >= targetDur 的最小选项
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* 2. 否则用 maxDur 贪心填充，余数从 options 中选最近 ≥ 选项
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*/
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export function computeSegmentPlan(
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targetDuration: number,
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durationOptions: DurationOption[]
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): SegmentPlan {
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const options = durationOptions
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.map(o => parseInt(o.value, 10))
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.filter(n => !isNaN(n) && n > 0)
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.sort((a, b) => a - b);
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// 兜底：无有效选项
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if (options.length === 0) {
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const count = Math.max(1, Math.ceil(targetDuration / FALLBACK_DURATION));
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const total = count * FALLBACK_DURATION;
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return {
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segments: Array(count).fill(FALLBACK_DURATION),
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actualTotal: total,
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isFixed: true,
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overflow: total - targetDuration,
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};
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}
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const isFixed = options.length === 1;
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const maxDur = options[options.length - 1];
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if (isFixed) {
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const fixedDur = options[0];
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const count = Math.max(1, Math.ceil(targetDuration / fixedDur));
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const total = count * fixedDur;
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return {
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segments: Array(count).fill(fixedDur),
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actualTotal: total,
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isFixed: true,
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overflow: total - targetDuration,
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};
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}
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// 可变时长：单段可覆盖
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if (targetDuration <= maxDur) {
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const best = options.find(d => d >= targetDuration) ?? maxDur;
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return {
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segments: [best],
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actualTotal: best,
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isFixed: false,
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overflow: best - targetDuration,
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};
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}
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// 可变时长：多段贪心
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const segments: number[] = [];
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let remaining = targetDuration;
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while (remaining > maxDur) {
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segments.push(maxDur);
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remaining -= maxDur;
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}
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// 余数：找最近的 >= remaining 选项
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const tail = options.find(d => d >= remaining) ?? maxDur;
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segments.push(tail);
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const actualTotal = segments.reduce((a, b) => a + b, 0);
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return {
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segments,
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actualTotal,
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isFixed: false,
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overflow: actualTotal - targetDuration,
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};
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}
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/**
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* 为单个 shot 选最合适的模型时长
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*
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* 找 >= targetDur 的最小选项，没有则取最大值
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*/
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export function findBestDuration(
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targetDur: number,
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durationOptions: DurationOption[]
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): number {
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const options = durationOptions
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.map(o => parseInt(o.value, 10))
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.filter(n => !isNaN(n) && n > 0)
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.sort((a, b) => a - b);
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if (options.length === 0) {
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return Math.min(Math.max(targetDur, 5), 10);
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}
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return options.find(d => d >= targetDur) ?? options[options.length - 1];
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}
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