57 lines
1.8 KiB
Markdown
57 lines
1.8 KiB
Markdown
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# `prism.FFmpeg`
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The FFmpeg transcoder is designed to take any media stream and pipe it into a spawned ffmpeg process.
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Make sure you have ffmpeg available on your system if you want to use it. Try installing [ffmpeg-binaries](https://www.npmjs.com/package/ffmpeg-binaries) if ffmpeg isn't already available in your path.
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## Usage
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```js
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new prism.FFmpeg(options);
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```
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Where options is an object containing the `args` property, an array of arguments to pass through to ffmpeg when spawning the process.
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## Example
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This stream is used heavily in [discord.js](https://discord.js.org/) to transcode media files to raw audio ready to be assembled into Opus packets to then send over voice connections, as such here is a relevant example:
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```js
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const fs = require('fs');
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const prism = require('prism-media');
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const input = fs.createReadStream('./file.mp3');
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const output = fs.createWriteStream('./output.pcm');
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const transcoder = new prism.FFmpeg({
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args: [
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'-analyzeduration', '0',
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'-loglevel', '0',
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'-f', 's16le',
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'-ar', '48000',
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'-ac', '2',
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],
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});
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input.pipe(transcoder).pipe(output);
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```
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By default, if your arguments are missing the `-i` flag, we will assume that you're going to pipe a stream into the ffmpeg process, so we'll prepend `['-i', '-']` for you.
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However, ffmpeg supports a [lot of protocols](https://ffmpeg.org/ffmpeg-protocols.html) so we can simplify the above example and probably reduce some overhead by telling ffmpeg where our file is rather than piping it in ourselves:
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```js
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const fs = require('fs');
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const prism = require('prism-media');
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const output = fs.createWriteStream('./output.pcm');
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const transcoder = new prism.FFmpeg({
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args: [
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'-i', 'file.mp3',
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'-analyzeduration', '0',
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'-loglevel', '0',
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'-f', 's16le',
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'-ar', '48000',
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'-ac', '2',
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],
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});
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transcoder.pipe(output);
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```
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