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render

The render command produces a recording of a Liqvid video as a "solid" (traditional mp4/webm) video file.

You will need to have ffmpeg installed and in your $PATH. In case you have issues installing it, this guide may help.

The syntax is

liqvid render
liqvid render -a <audio-file> -o <output>
liqvid render -u <url>

For example,

liqvid render -a ./audio/audio.mp4 -o out.mp4 -u http://localhost:8080

To avoid passing command line options every time, you can create a liqvid.config.ts file. This should export an object with a render key containing the options for this command. Here is an example:

// liqvid.config.ts
const os = require("os");

module.exports = {
  render: {
    audioFile: "./audio/audio.mp4",
    concurrency: os.cpus().length,
    imageFormat: "png"
  },
  thumbs: {
    /* ... */
  }
};

You can specify a different location for the configuration file using the --config option.

What to render​

--audio-file, -a​

Path to audio file. If not specified, the video will not have audio.

--output, -o​

Output filename. Defaults to ./video.mp4.

--url, -u​

URL of video to render. Defaults to http://localhost:3000/dist/.

General options​

--browser-executable, -x​

Path to a Chrome/Chromium executable. If not specified and a suitable executable cannot be found, one will be downloaded during rendering.

--concurrency, -n​

How many threads to use. Defaults to half of the available CPUs.

--config​

Path to a configuration file to load options from. Defaults to ./liqvid.config.ts.

Input options​

--duration, -d​

Duration, specify as [[hh:]mm:]ss[.ms]. Cannot be used with --end.

--end, -e​

End time, specify as [[hh:]mm:]ss[.ms]. Defaults to null, meaning the end of the video. Cannot be used with --duration.

--sequence, -S​

Boolean flag to output an image sequence instead of a video. If set, <outfile> will be interpreted as a directory (and created if it does not already exist). This is useful if you want to run ffmpeg on the images yourself.

--start, -s​

Start time, specify as [[hh:]mm:]ss[.ms]. Defaults to 0, meaning the start of the video.

info

--start, --duration, and --end apply to both the audio file (if any) and the video. At this time, it is not possible to configure these separately.

Frame formatting​

--height, -h​

Video height. Defaults to 800.

--image-format, -F​

Image format for the frames, either jpeg or png. Defaults to jpeg.

--quality, -q​

Value between 0 and 100 for quality of the frames. Only applies when --image-format is jpeg.

--width, -w​

Video width. Defaults to 1280.

Video options​

The exact command that we pass to ffmpeg is

ffmpeg
  -framerate <fps> -i <frames-dir> \ # frames
  -ss <start> -t <duration> [audio-args] -i <audio-file> \ # audio
  -pix_fmt <pixel-format> -y [video-args] <outfile> # video

See the ffmpeg documentation for available options. The -y flag (which tells ffmpeg to overwrite the output file without asking) cannot currently be overridden. If no audio file is specified, the third line will not be included.

--audio-args, -A​

Additional flags to pass to ffmpeg, applying to the audio file. If no audio file is specified, this has no effect.

--fps, -r​

Frames per second. Defaults to 30.

--pixel-format, -P​

Pixel format for ffmpeg. Defaults to yuv420p.

tip

If outfile is an mp4 video, formats other than 4:2:0 will not work reliably, c.f. Encoding for dumb players.

--video-args, -V​

Additional flags to pass to ffmpeg, applying to the video outfile.