[FIG(quote)[
[FIGCAPTION[
[1] [CITE@en[FFmpeg Protocols Documentation]]
([TIME[2017-01-22 02:22:36 +09:00]])
<https://ffmpeg.org/ffmpeg-protocols.html#async>
]FIGCAPTION]

> Asynchronous data filling wrapper for input stream.
> Fill data in a background thread, to decouple I/O operation from demux thread.
> async:URL
> async:http://host/resource
> async:cache:http://host/resource

]FIG]