concatDemuxer implemented

docs/api.md

@@ -1,5 +1,4 @@
-API
-===
+# API
 
 - [createWorker()](#create-worker)
   - [Worker.load](#worker-load)
@@ -14,6 +13,7 @@ API
 ---
 
 <a name="create-worker"></a>
+
 ## createWorker(options): Worker
 
 createWorker is a factory function that creates a ffmpeg worker, a worker is basically a Web Worker in browser and Child Process in Node.
@@ -27,17 +27,18 @@ createWorker is a factory function that creates a ffmpeg worker, a worker is bas
   - `logger` a function to log the progress, a quick example is `m => console.log(m)`
   - `progress` a function to trace the progress, a quick example is `p => console.log(p)`
 
-
 **Examples:**
 
 ```javascript
 const { createWorker } = FFmpeg;
 const worker = createWorker({
-  corePath: './node_modules/@ffmpeg/core/ffmpeg-core.js',
-  logger: m => console.log(m),
+  corePath: "./node_modules/@ffmpeg/core/ffmpeg-core.js",
+  logger: m => console.log(m)
 });
 ```
+
 <a name="worker-load"></a>
+
 ### Worker.load(jobId): Promise
 
 Worker.load() loads ffmpeg-core.js script (download from remote if not presented), it makes Web Worker/Child Process ready for next action.
@@ -55,6 +56,7 @@ Worker.load() loads ffmpeg-core.js script (download from remote if not presented
 ```
 
 <a name="worker-write"></a>
+
 ### Worker.write(path, data): Promise
 
 Worker.write() writes data to specific path in Emscripten file system, it is an essential step before doing any other tasks.
@@ -68,11 +70,15 @@ Worker.write() writes data to specific path in Emscripten file system, it is an
 
 ```javascript
 (async () => {
-  await worker.write('flame.avi', 'http://localhost:3000/tests/assets/flame.avi');
+  await worker.write(
+    "flame.avi",
+    "http://localhost:3000/tests/assets/flame.avi"
+  );
 })();
 ```
 
 <a name="worker-writeText"></a>
+
 ### Worker.writeText(path, text): Promise
 
 Worker.write() writes text data to specific path in Emscripten file system.
@@ -86,11 +92,12 @@ Worker.write() writes text data to specific path in Emscripten file system.
 
 ```javascript
 (async () => {
-  await worker.write('sub.srt', '...');
+  await worker.write("sub.srt", "...");
 })();
 ```
 
 <a name="worker-read"></a>
+
 ### Worker.read(path, del): Promise
 
 Worker.read() reads data from file system, often used to get output data after specific task.
@@ -104,11 +111,12 @@ Worker.read() reads data from file system, often used to get output data after s
 
 ```javascript
 (async () => {
-  const { data } = await worker.read('output.mp4');
+  const { data } = await worker.read("output.mp4");
 })();
 ```
 
 <a name="worker-remove"></a>
+
 ### Worker.remove(path): Promise
 
 Worker.remove() removes files in file system, it will be better to delete unused files if you need to run ffmpeg.js multiple times.
@@ -121,11 +129,12 @@ Worker.remove() removes files in file system, it will be better to delete unused
 
 ```javascript
 (async () => {
-  await worker.remove('output.mp4');
+  await worker.remove("output.mp4");
 })();
 ```
 
 <a name="worker-transcode"></a>
+
 ### Worker.transcode(inputPath, outputPath, options, del, jobId): Promise
 
 Worker.transcode() transcode a video file to another format.
@@ -142,11 +151,12 @@ Worker.transcode() transcode a video file to another format.
 
 ```javascript
 (async () => {
-  await worker.transcode('flame.avi', 'output.mp4', '-s 1920x1080');
+  await worker.transcode("flame.avi", "output.mp4", "-s 1920x1080");
 })();
 ```
 
 <a name="worker-trim"></a>
+
 ### Worker.trim(inputPath, outputPath, from, to, options, del, jobId): Promise
 
 Worker.trim() trims video to specific interval.
@@ -165,11 +175,34 @@ Worker.trim() trims video to specific interval.
 
 ```javascript
 (async () => {
-  await worker.trim('flame.avi', 'output.mp4', 1, 2);
+  await worker.trim("flame.avi", "output.mp4", 1, 2);
+})();
+```
+
+<a name="worker-concatDemuxer"></a>
+
+### Worker.concatDemuxer(inputPaths, outputPath, options, del, jobId): Promise
+
+Worker.concatDemuxer() concatenates multiple videos using concatDemuxer. This method won't encode the videos again. But it has its limitations. See [Concat demuxer Wiki](https://trac.ffmpeg.org/wiki/Concatenate)
+
+**Arguments:**
+
+- `inputPaths` input file paths as an Array, the input files should be written through Worker.write()
+- `outputPath` output file path, can be read with Worker.read() later
+- `options` a string to add extra arguments to ffmpeg
+- `del` a boolean to determine whether to delete input file after the task is done, default: true
+- `jobId` check Worker.load()
+
+**Examples:**
+
+```javascript
+(async () => {
+  await worker.trim(["flame-1.avi", "flame-2.avi"], "output.mp4");
 })();
 ```
 
 <a name="worker-run"></a>
+
 ### Worker.run(args, options, jobId): Promise
 
 Worker.run() is similar to FFmpeg cli tool, aims to provide maximum flexiblity for users.
@@ -184,6 +217,9 @@ Worker.run() is similar to FFmpeg cli tool, aims to provide maximum flexiblity f
 
 ```javascript
 (async () => {
-  await worker.run('-i /data/flame.avi -s 1920x1080 output.mp4', { inputPath: 'flame.avi', outputPath: 'output.mp4' });
+  await worker.run("-i /data/flame.avi -s 1920x1080 output.mp4", {
+    inputPath: "flame.avi",
+    outputPath: "output.mp4"
+  });
 })();
 ```