Allow custom output args mifi#27 mifi#36

README.md

@@ -176,6 +176,7 @@ Edit specs are JavaScript / JSON objects describing the whole edit operation wit
 | `width` | `--width` | Width which all media will be converted to | `640` | |
 | `height` | `--height` | Height which all media will be converted to | auto based on `width` and aspect ratio of **first video** | |
 | `fps` | `--fps` | FPS which all videos will be converted to | First video FPS or `25` | |
+| `customOutputArgs` | | Specify custom output codec/format arguments for ffmpeg (See [example](https://github.com/mifi/editly/blob/master/examples/customOutputArgs.json5)) | auto (h264) | |
 | `allowRemoteRequests` | `--allow-remote-requests` | Allow remote URLs as paths | `false` | |
 | `fast` | `--fast`, `-f` | Fast mode (low resolution and FPS, useful for getting a quick preview ⏩) | `false` | |
 | `defaults.layer.fontPath` | `--font-path` | Set default font to a .ttf | System font | |

examples/customOutputArgs.json5

@@ -0,0 +1,7 @@
+{
+  outPath: './customOutputArgs.webp',
+  clips: [
+    { duration: 2, layers: [{ type: 'title-background', text: 'Custom output args' }] },
+  ],
+  customOutputArgs: ['-compression_level', '5', '-qscale', '60', '-vcodec', 'libwebp'],
+}

index.js

@@ -40,6 +40,7 @@ const Editly = async (config = {}) => {
     allowRemoteRequests,
     audioNorm,
     outputVolume,
+    customOutputArgs,
 
     ffmpegPath = 'ffmpeg',
     ffprobePath = 'ffprobe',
@@ -177,13 +178,16 @@ const Editly = async (config = {}) => {
     return runGlTransitionOnFrame({ fromFrame, toFrame, progress, transitionName, transitionParams });
   }
 
-  function startFfmpegWriterProcess() {
+  function getOutputArgs() {
+    if (customOutputArgs) {
+      assert(Array.isArray(customOutputArgs), 'customOutputArgs must be an array of arguments');
+      return customOutputArgs;
+    }
+
     // https://superuser.com/questions/556029/how-do-i-convert-a-video-to-gif-using-ffmpeg-with-reasonable-quality
-    const outputArgs = isGif ? [
-      '-vf',
-      `format=rgb24,fps=${fps},scale=${width}:${height}:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse`,
+    const videoOutputArgs = isGif ? [
+      '-vf', `format=rgb24,fps=${fps},scale=${width}:${height}:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse`,
       '-loop', 0,
-      '-y', outPath,
     ] : [
       '-vf', 'format=yuv420p',
       '-vcodec', 'libx264',
@@ -192,9 +196,14 @@ const Editly = async (config = {}) => {
       '-crf', '18',
 
       '-movflags', 'faststart',
-      '-y', outPath,
     ];
 
+    const audioOutputArgs = audioFilePath ? ['-acodec', 'aac', '-b:a', '128k'] : [];
+
+    return [...audioOutputArgs, ...videoOutputArgs];
+  }
+
+  function startFfmpegWriterProcess() {
     const args = [
       ...(enableFfmpegLog ? [] : ['-hide_banner', '-loglevel', 'error']),
 
@@ -210,9 +219,9 @@ const Editly = async (config = {}) => {
       ...(!isGif ? ['-map', '0:v:0'] : []),
       ...(audioFilePath ? ['-map', '1:a:0'] : []),
 
-      ...(audioFilePath ? ['-acodec', 'aac', '-b:a', '128k'] : []),
+      ...getOutputArgs(),
 
-      ...outputArgs,
+      '-y', outPath,
     ];
     if (verbose) console.log('ffmpeg', args.join(' '));
     return execa(ffmpegPath, args, { encoding: null, buffer: false, stdin: 'pipe', stdout: process.stdout, stderr: process.stderr });