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Nov 4, 2021
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viewof videoFile = html`<input type="file" accept=".mp4,.mov,.webm" />`
viewof inputFPS = html`<input type=number value=30 />`
maxFrameCountGuess = Math.round(duration * inputFPS)
outputWidth = Math.floor(options.outputScale * videoWidth)
outputHeight = Math.floor(options.outputScale * videoHeight)
previewImage = html`<div>${previewScrub}</div><img src="${frames[previewScrub].data}">`
videoEl = {
const videoEl = html`<video src="${URL.createObjectURL(
videoFile
)}" controls style="max-width: 100%;" />`;
videoEl.addEventListener('loadedmetadata', function(event) {
mutable videoWidth = videoEl.videoWidth;
mutable videoHeight = videoEl.videoHeight;
});
videoEl.addEventListener('durationchange', function(event) {
mutable duration = videoEl.duration;
});
function setCurrentTime() {
mutable currentTime = videoEl.currentTime;
}
videoEl.addEventListener('seeked', setCurrentTime);
videoEl.addEventListener('timeupdate', setCurrentTime);
return videoEl;
}
mutable videoWidth = 0
mutable videoHeight = 0
mutable duration = 0
mutable currentTime = 0
mutable busy = false
mutable progress = 0
outputFrameRate = Math.max(1, Math.floor(options.numFrames / duration))
async function seekTo(videoEl, time) {
return new Promise((resolve, reject) => {
const handleSeeked = function() {
videoEl.removeEventListener('seeked', handleSeeked);
resolve(videoEl.currentTime);
};
videoEl.addEventListener('seeked', handleSeeked);
videoEl.currentTime = time;
});
}
async function extractFrames({
videoEl,
clipStart,
clipEnd,
numFrames,
quality = 0.8,
outputScale = 1
}) {
// if (busy) {
// throw new Error('Already encoding, wait a moment...');
// }
// mutable busy = true;
videoEl.pause();
const canvas = document.createElement('canvas');
const context = canvas.getContext('2d');
const outputWidth = outputScale * videoEl.videoWidth;
const outputHeight = outputScale * videoEl.videoHeight;
canvas.width = outputWidth;
canvas.height = outputHeight;
const frames = [];
for (let i = 0; i < numFrames; i++) {
const duration = clipEnd - clipStart;
if (duration <= 0) {
throw new Error('clipEnd is before clipStart');
}
const time = i * (duration / (Math.max(2, numFrames) - 1)) + clipStart;
// In threory, waits until seeked time is in view
const seekedTime = await seekTo(videoEl, time);
context.drawImage(videoEl, 0, 0, outputWidth, outputHeight);
frames.push({
time,
seekedTime,
data: canvas.toDataURL('image/jpeg', quality)
});
mutable progress = (i + 1) / numFrames;
}
// mutable busy = false;
return frames;
}
frames = extractFrames({
videoEl,
...options
})
preview = {
const previewImages = frames.map(
({ data }) => html`<img src="${data}" style="max-width: 128px">`
);
return html`<div>${previewImages}</div>`;
}
lottieJson = frames.reduce(
function(lottie, frame, index) {
const id = "fr_" + index;
const w = outputWidth;
const w2 = Math.floor(w / 2);
const h = outputHeight;
const h2 = Math.floor(h / 2);
lottie.assets.push({
id,
w,
h,
u: "",
p: frame.data,
e: 1
});
lottie.layers.push({
ddd: 0,
ind: index + 1,
ty: 2,
nm: id + ".jpg",
cl: "jpg",
refId: id,
sr: 1,
ks: {
o: { a: 0, k: 100, ix: 11 },
r: { a: 0, k: 0, ix: 10 },
p: { a: 0, k: [w2, h2, 0], ix: 2 },
a: { a: 0, k: [w2, h2, 0], ix: 1 },
s: { a: 0, k: [100, 100, 100], ix: 6 }
},
ao: 0,
ip: index,
op: index + 1,
st: index,
bm: 0
});
return lottie;
},
{
v: "5.5.2",
fr: outputFrameRate,
ip: 0,
op: options.numFrames,
w: outputWidth,
h: outputHeight,
nm: "@forresto/movie-to-lottie",
ddd: 0,
assets: [],
layers: [],
markers: []
}
)
outputLink = {
const jsonString = JSON.stringify(lottieJson);
const blob = new Blob([jsonString], { type: "application/json" });
const url = URL.createObjectURL(blob);
const outputFilename = videoFile.name + ".lottie.json";
return html`<a href="${url}" download="${outputFilename}">${outputFilename} (${Math.round(
blob.size / 1024
)}kb)</a>`;
}
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