107 lines
3.5 KiB
JavaScript
107 lines
3.5 KiB
JavaScript
export class HlsDownloader {
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constructor() {}
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async downloadHlsStream(masterUrl, options = {}) {
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const { onProgress, signal } = options;
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const response = await fetch(masterUrl, { signal });
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const masterText = await response.text();
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const variantUrl = this.getBestVariantUrl(masterUrl, masterText);
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const mediaResponse = await fetch(variantUrl, { signal });
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const mediaText = await mediaResponse.text();
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const segments = this.parseMediaPlaylist(variantUrl, mediaText);
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if (segments.length === 0) {
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throw new Error('No segments found in HLS playlist');
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}
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const chunks = [];
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let downloadedBytes = 0;
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const totalSegments = segments.length;
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for (let i = 0; i < totalSegments; i++) {
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if (signal?.aborted) throw new Error('AbortError');
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const segmentUrl = segments[i];
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const segmentResponse = await fetch(segmentUrl, { signal });
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if (!segmentResponse.ok) {
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throw new Error(`Failed to fetch segment ${i}: ${segmentResponse.status}`);
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}
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const chunk = await segmentResponse.arrayBuffer();
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chunks.push(chunk);
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downloadedBytes += chunk.byteLength;
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if (onProgress) {
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onProgress({
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stage: 'downloading',
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receivedBytes: downloadedBytes,
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totalBytes: undefined,
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currentSegment: i + 1,
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totalSegments: totalSegments,
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});
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}
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}
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const mimeType = segments[0].endsWith('.m4s') || segments[0].includes('mp4') ? 'video/mp4' : 'video/mp2t';
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return new Blob(chunks, { type: mimeType });
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}
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getBestVariantUrl(masterUrl, masterText) {
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if (!masterText.includes('#EXT-X-STREAM-INF')) {
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return masterUrl;
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}
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const lines = masterText.split('\n');
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const variants = [];
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let currentVariant = null;
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for (const line of lines) {
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const trimmed = line.trim();
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if (trimmed.startsWith('#EXT-X-STREAM-INF:')) {
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const bandwidthMatch = trimmed.match(/BANDWIDTH=(\d+)/);
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const resolutionMatch = trimmed.match(/RESOLUTION=(\d+x\d+)/);
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currentVariant = {
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bandwidth: bandwidthMatch ? parseInt(bandwidthMatch[1], 10) : 0,
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resolution: resolutionMatch ? resolutionMatch[1] : 'unknown',
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};
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} else if (trimmed && !trimmed.startsWith('#')) {
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if (currentVariant) {
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currentVariant.url = this.resolveUrl(masterUrl, trimmed);
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variants.push(currentVariant);
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currentVariant = null;
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}
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}
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}
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if (variants.length === 0) return masterUrl;
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variants.sort((a, b) => b.bandwidth - a.bandwidth);
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return variants[0].url;
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}
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parseMediaPlaylist(mediaUrl, mediaText) {
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const lines = mediaText.split('\n');
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const segments = [];
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for (const line of lines) {
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const trimmed = line.trim();
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if (trimmed && !trimmed.startsWith('#')) {
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segments.push(this.resolveUrl(mediaUrl, trimmed));
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}
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}
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return segments;
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}
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resolveUrl(baseUrl, relativeUrl) {
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try {
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return new URL(relativeUrl, baseUrl).href;
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} catch {
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return relativeUrl;
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}
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}
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}
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