fix resizeMode cover issue with on resolutions (do calculations in JS instead of ffmpeg)

examples/pip.json5

@@ -1,14 +1,14 @@
 {
   outPath: './pip.mp4',
   width: 1280, height: 720, fps: 30,
-  enableFfmpegLog: true,
   defaults: {
     layer: { fontPath: './assets/Patua_One/PatuaOne-Regular.ttf' },
   },
   clips: [
     { duration: 4, layers: [
       { type: 'rainbow-colors' },
-      { type: 'video', path: './assets/tungestolen.mp4', resizeMode: 'contain', width: 0.4, height: 0.4, top: 0.05, left: 0.95, originY: 'top', originX: 'right' },
+      { type: 'video', path: './assets/tungestolen.mp4', resizeMode: 'cover', width: 0.3, height: 0.4, top: 0.05, left: 0.95, originY: 'top', originX: 'right' },
+      { type: 'video', path: './assets/tungestolen.mp4', resizeMode: 'cover', width: 0.4, height: 0.2, top: 0.05, left: 0.05, originY: 'top', originX: 'left' },
       { type: 'title', position: 'bottom', text: 'Picture-in-Picture' }
     ] },
   ],

sources/videoFrameSource.js

@@ -14,14 +14,15 @@ module.exports = async ({ width: canvasWidth, height: canvasHeight, channels, fr
   const left = leftRel * canvasWidth;
   const top = topRel * canvasHeight;
 
+  const ratioW = requestedWidth / inputWidth;
+  const ratioH = requestedHeight / inputHeight;
+  const inputAspectRatio = inputWidth / inputHeight;
+
   let targetWidth = requestedWidth;
   let targetHeight = requestedHeight;
 
+  let scaleFilter;
   if (['contain', 'contain-blur'].includes(resizeMode)) {
-    const ratioW = requestedWidth / inputWidth;
-    const ratioH = requestedHeight / inputHeight;
-    const inputAspectRatio = inputWidth / inputHeight;
-
     if (ratioW > ratioH) {
       targetHeight = requestedHeight;
       targetWidth = Math.round(requestedHeight * inputAspectRatio);
@@ -29,15 +30,27 @@ module.exports = async ({ width: canvasWidth, height: canvasHeight, channels, fr
       targetWidth = requestedWidth;
       targetHeight = Math.round(requestedWidth / inputAspectRatio);
     }
-  }
 
-  const frameByteSize = targetWidth * targetHeight * channels;
+    scaleFilter = `scale=${targetWidth}:${targetHeight}`;
+  } else if (resizeMode === 'cover') {
+    let scaledWidth;
+    let scaledHeight;
 
-  // TODO assert that we have read the correct amount of frames
+    if (ratioW > ratioH) {
+      scaledWidth = requestedWidth;
+      scaledHeight = Math.round(requestedWidth / inputAspectRatio);
+    } else {
+      scaledHeight = requestedHeight;
+      scaledWidth = Math.round(requestedHeight * inputAspectRatio);
+    }
 
-  const buf = Buffer.allocUnsafe(frameByteSize);
-  let length = 0;
-  // let inFrameCount = 0;
+    // TODO improve performance by crop first, then scale?
+    scaleFilter = `scale=${scaledWidth}:${scaledHeight},crop=${targetWidth}:${targetHeight}`;
+  } else { // 'stretch'
+    scaleFilter = `scale=${targetWidth}:${targetHeight}`;
+  }
+
+  if (verbose) console.log(scaleFilter);
 
   let ptsFilter = '';
   if (speedFactor !== 1) {
@@ -45,10 +58,13 @@ module.exports = async ({ width: canvasWidth, height: canvasHeight, channels, fr
     ptsFilter = `setpts=${speedFactor}*PTS,`;
   }
 
-  let scaleFilter;
-  if (['stretch', 'contain', 'contain-blur'].includes(resizeMode)) scaleFilter = `scale=${targetWidth}:${targetHeight}`;
-  // Cover: https://unix.stackexchange.com/a/192123
-  else scaleFilter = `scale=(iw*sar)*max(${targetWidth}/(iw*sar)\\,${targetHeight}/ih):ih*max(${targetWidth}/(iw*sar)\\,${targetHeight}/ih),crop=${targetWidth}:${targetHeight}`;
+  const frameByteSize = targetWidth * targetHeight * channels;
+
+  // TODO assert that we have read the correct amount of frames
+
+  const buf = Buffer.allocUnsafe(frameByteSize);
+  let length = 0;
+  // let inFrameCount = 0;
 
   // https://forum.unity.com/threads/settings-for-importing-a-video-with-an-alpha-channel.457657/
   const streams = await readFileStreams(ffprobePath, path);