kopia lustrzana https://github.com/mifi/lossless-cut
68 wiersze
2.5 KiB
JavaScript
68 wiersze
2.5 KiB
JavaScript
import { getRealVideoStreams, getVideoTimebase } from './util/streams';
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import { readKeyframesAroundTime, findNextKeyframe, findKeyframeAtExactTime } from './ffmpeg';
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const { stat } = window.require('fs-extra');
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// eslint-disable-next-line import/prefer-default-export
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export async function getSmartCutParams({ path, videoDuration, desiredCutFrom, streams }) {
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const videoStreams = getRealVideoStreams(streams);
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if (videoStreams.length === 0) throw new Error('Smart cut only works on videos');
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if (videoStreams.length > 1) throw new Error('Can only smart cut video with exactly one video stream');
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const videoStream = videoStreams[0];
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const readKeyframes = async (window) => readKeyframesAroundTime({ filePath: path, streamIndex: videoStream.index, aroundTime: desiredCutFrom, window });
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let keyframes = await readKeyframes(10);
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const keyframeAtExactTime = findKeyframeAtExactTime(keyframes, desiredCutFrom);
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if (keyframeAtExactTime) {
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console.log('Start cut is already on exact keyframe', keyframeAtExactTime.time);
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return {
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cutFrom: keyframeAtExactTime.time,
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videoStreamIndex: videoStream.index,
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segmentNeedsSmartCut: false,
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};
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}
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let nextKeyframe = findNextKeyframe(keyframes, desiredCutFrom);
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if (nextKeyframe == null) {
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// try again with a larger window
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keyframes = await readKeyframes(60);
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nextKeyframe = findNextKeyframe(keyframes, desiredCutFrom);
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}
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if (nextKeyframe == null) throw new Error('Cannot find any keyframe after the desired start cut point');
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console.log('Smart cut from keyframe', { keyframe: nextKeyframe.time, desiredCutFrom });
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let videoBitrate = parseInt(videoStream.bit_rate, 10);
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if (Number.isNaN(videoBitrate)) {
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console.warn('Unable to detect input bitrate');
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const stats = await stat(path);
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videoBitrate = stats.size / videoDuration;
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}
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const { codec_name: videoCodec } = videoStream;
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if (videoCodec == null) throw new Error('Unable to determine codec for smart cut');
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const timebase = getVideoTimebase(videoStream);
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if (timebase == null) console.warn('Unable to determine timebase', videoStream.time_base);
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// seems like ffmpeg handles this itself well when encoding same source file
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// const videoLevel = parseLevel(videoStream);
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// const videoProfile = parseProfile(videoStream);
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return {
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cutFrom: nextKeyframe.time,
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videoStreamIndex: videoStream.index,
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segmentNeedsSmartCut: true,
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videoCodec,
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videoBitrate: Math.floor(videoBitrate),
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videoTimebase: timebase,
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};
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}
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